CHAPTER ONE: THE EVOLUTION OF LOG ANALYSIS METHODS

Table Of Contents
1.00 Introduction to This Chapter
1.01 The Early Years (1929 - 1949)
1.02 The Middle Years (1949 - 1968)
1.03 The Recent Years (1969 - 1985)
1.04 The State of the Art (1985 - 2000)
1.05 Log Interpretation in the Future
1.06 A True History of Oil and Gas Development
1.07 History of Oil and Gas in Canada
1.08 History of Well Logging in Canada
1.09 In Conclusion
1.10 Exercises For Chapter One
1.11 Bibliography For Chapter One

Click here to go to NEXT CHAPTER

Publication History: Sections 1.00 to 1.03 were originally published in Offshore Resources Magazine in three installments in May, July, and September 1984. Reprinted in CWLS Journal February 1985. Published as Chapter One of the Log Analysis
Handbook, Pennwell 1986. New material
added to this eText edition and all
sections edited and updated Feb 2001.

Section 1.04 was originally presented by the author as "The Future of Petrophysics in Reservoir Description”, Keynote Address to the First Annual Well Log Analysis / Formation Evaluation Conference, Tripoli, Libya, 28 - 31 October 2000. It was published in the Transactions of this conference and reprinted in Journal of the Libyan Petroleum Research Center 2001.
Section 1.08 was originally published in the Journal of Canadian Petroleum, Jan 1982, and was reprinted in CWLS Journal, Dec 1982 and in CWLS InSite Sep 2003. Sections 1.06 and 1.07 added May 2004.

CHAPTER ONE: THE EVOLUTION OF LOG ANALYSIS METHODS

1.00 Introduction to This Chapter
The oil industry has had an impact on every human on earth. The evolution of log analysis methods over the years is less dramatic, but equally fascinating and illuminating.

Obsolete but traditional definitions, abbreviations, symbols, and methods still pervade our industry. Newcomers often wonder why these old-fashioned ideas persist. In many cases, methods were developed which required better logging tools or more powerful computational methods than were available at the time. Such methods fell into disuse, to be resurrected years later when the appropriate tools were developed. An appreciation of the history of logging and the development sequence of analytical methods will help any geologist, geophysicist, or engineer who works with well logs.

Well logging is a relatively young science, but initial work in the field dates back over 130 years. As early as 1869, Lord Kelvin in Britain was making interpretations of heat flow in shallow well bores by measuring temperature versus depth. 100 years later, the Apollo astronauts set up heat flow experiments in the lunar regolith. The holes were only 1.5 to 3.2 meters deep and the logging tool was stationary, but the results were recorded versus depth, so these surveys are the first logs recorded off planet Earth.

FIGURE 1.00: Dave Scott of Apollo 15 running the first logs on the Moon in 1971 (NASA Photo)

The first surface measurements of electrical resistance of rocks were made by Conrad Schlumberger in 1912. This was repeated on the Moon by Apollo astronauts also. The results: "The Moon is very dry". Shucks, Sherlock!

A patent for a single electrode resistivity device was issued in 1883 to Fred Brown, but it appears not to have seen use until 1913 in a mining drill hole.

The initial success with surface resistivity led Conrad and his brother Marcel Schlumberger to consider similar measurements in boreholes. In 1927, they convinced the Pechlebronn Oil Company, drilling in Alsace, France, to try such electrical measurements as an aid to understanding the rock layers. The first such log in the USA was run on 17 August l929 for Shell Oil Company in Kern County, California. Logs were run that same year in Venezuela, Russia, and India.

The first well logs in Canada were run in 1937 for a gold exploration project in Ontario, and in 1939 for oil in Alberta. After the Great Depression, well logging was common worldwide.

1.01 The Early Years (1929 - 1949)
The first recognizable technical paper on log interpretation, by the Schlumberger brothers and E.G. Leonardon, describing the electrical resistivity log, was published in 1934. Log analysis using these new tools involved curve-shape recognition - still a valid and commonly used qualitative approach to interpretation. Log curve shapes are determined visually from the appearance of the recorded data when plotted versus depth. These curve shapes were related to rock sample and core description data to determine general rules-of-thumb for separating permeable, porous, oil bearing beds from non-productive zones.

FIG 1.01: First Schlumberger Log 1927	FIG 1.02: Curve Shape Analysis 1950

The early success of curve shape interpretation was quite accidental. It depended on the fact that the formation water in the first wells logged was quite conductive due to dissolved salt. Had these logs been run in west Texas at the beginning of the twenties, the fresh water sands may have given such confused interpretations that well logging might never have become popular.

Seven years after the original Schlumberger paper, in 1941, G. E. Archie developed the empirical data behind the concept of "formation factor" - a term used to relate the porosity, the resistivity log reading, and the water saturation in the zone. This revolutionized log analysis, as the subject was now quantitative rather than only qualitative. In practice, however, the errors due to borehole effects on the measurements and uncertainty about other items relating formation factor to porosity, prevented really accurate results.

W. O. Winsauer, with others, modified the Archie equation slightly in 1952. This formula is used today but is commonly known as the Archie equation. M. P. Tixier of Schlumberger published the details of the so-called Rocky Mountain or resistivity ratio method in 1949. It was based on Archie's water saturation equation, but avoided the need to know porosity by using the ratio of deep and shallow resistivity readings.

Studies of invasion profiles and water chemistry reactions were thus common during this period.

From its earliest beginnings, the spontaneous potential log was interpreted by its curve shape. Since an SP voltage was developed across sandstones, and not along shale beds, it was relatively easy to identify sandstone from shale by the shape of the SP curve. Between 1943 and 1949, much work was done on the theory behind the spontaneous potential. Interpretation from this curve is still popular because it gives approximate values for formation water resistivity in clean (non-shaly) sandstone formations, or the shaliness of the formation in shaly sandstones.

Shale content calculations were enhanced by the appearance of the gamma ray log in 1934 because shale emitted natural gamma rays and clean sandstone and limestone did not. The log was calibrated to present a curve similar in shape to the spontaneous potential log. Although the gamma ray log has existed for seventy years, its appearance has not changed much. However, its resolution and accuracy have improved greatly due to more efficient and smaller gamma ray detectors.

The electrical, SP, and gamma ray logs all measured the average value of rock properties over eighteen inches to five feet of rock thickness. Beds thinner than this could not be detected or evaluated. The microlog was introduced in 1948 and allowed resistivity in beds as thin as two or three inches to be measured at a correspondingly shallow depth of investigation into the rock.

The curve shape approach to analysis was commonly used for microlog data, although laboratory derived charts allowed quantitative interpretation of formation factor, and as a result, porosity. The curve shape analysis for micrologs provided rapid visual identification of zones which were invaded by drilling fluid, and were thus permeable to some small degree. The log is still used today for this purpose.

The structural dip of rock formations is an important piece of knowledge for geologists. The first dipmeter log using three simultaneous spontaneous potential measurements spaced equally around the perimeter of the borehole, was run in 1942. It was superceded in 1947 by three simultaneous resistivity measurements. The theory of interpretation was simple. Slight offsets in the depth of the bed boundaries recorded by each of the three curves, plus the tool geometry, hole diameter, and tool orientation in space, could be reduced to give the dip of the bed boundary. Initially this was done by hand comparison, later in manually operated optical comparators and now by computer cross-correlation. The work was tedious and fraught with difficult decisions when the curves wiggled too much or not enough.

The modern dipmeter tool, first used in 1969, records four or more simultaneous resistivity curves, which provides considerable redundancy, and hence improved quality in the results. Data is often so good as to allow interpretation of stratigraphic features, such as crossbedding in sandstone deposits, as well as the much larger structural features of the rock layers detected by earlier tools.

The section gauge (or caliper log) also appeared in 1942 and made the application of borehole size corrections to all kinds of resistivity logs possible. The use of laboratory derived departure curves for this purpose, (between 1949 and 1955), was a common event in a log analyst's life. The corrections were seldom satisfying and may have been "gilding the lily" somewhat. Modern resistivity logs need little borehole correction if run in a well designed mud system in a reasonably good hole.

Additional logging tools have existed for a long time, and are used as aids to interpretation of other logs. One is the formation tester, which measures the formation pressure and obtains a fluid sample, usually of the invaded zone. It was first run in l957. Refinements with digital recording techniques proved very helpful in sorting out reservoir fluid content and reservoir continuity. The log made by the formation tester is of pressure versus time instead of a depth dependent log. Many such tests taken at different depths can provide a formation pressure versus depth log for analysis of pressure gradients.

The sidewall core gun (sample taker) was first used in l942. It used a large hollow bullet, tied to the tool by wires, to retrieve a small plug of rock from the well bore. Anywhere from a few to forty eight bullets could be shot sequentially in one trip into the well. Other than an SP or GR correlation log taken for depth control, no real log is recorded by the sample taker. Other types of core retriever have been used with limited success.

The temperature log, used to detect entry of gas into the well bore, was made available about l936. It was also used to determine formation temperature and temperature gradient.

Much evolution was going on behind the scenes that the log analyst never really appreciated, but the logging engineer did. The rag-line logging cable gave way in l947 to steel armoured multiconductor cable, which was far stronger and more reliable. Today, fiber optic cables are sometimes used. The tools evolved from purely electrical devices with ammeters and voltmeters, to vacuum tubes in the late forties, to transistors in the early sixties and finally integrated circuits and computers in the seventies and eighties.

Trucks changed radically from short wheel base, opencab flat decks with equipment bolted to the floor and shaded from the elements by an umbrella, to canvas covered vans in the early forties. Bread wagon style panel vans appeared in the late forties, to be superceded by the six and ten wheel "corn binders" of the fifties and sixties. The air conditioned behemoths of today, that look ever so much like space age garbage trucks, are the result of the computer revolution.

FIGURE 1.03: Early Logging Trucks c.1934 (Schlumberger photos)

Service availability, both in the number of trucks and the number of locations where they were available, increased dramatically. The far flung network was held together by the professionalism and integrity of the early pioneers. Today it is big business - multi-national and vertically integrated.

Trucks were moved offshore by barge and boat in the forties, and finally in 1947 when you couldn't see land from the rig anymore, genuine offshore skid units were built and placed on the rigs. Wave compensation devices and corrosion engineering solved many initial problems by the late fifties.

In sum, the early years were a period of invention and ingenuity - solving problems as they arose, and surviving the Great Depression and World War II by sheer determination.

1.02 The Middle Years (1949 - 1969)
All the logs mentioned so far, except the caliper, needed a conductive fluid in the borehole in order to operate. The induction log was introduced in 1949 to overcome this requirement in holes drilled with air or oil based drilling mud. The log was calibrated to read rock conductivity by inducing currents with electromagnetic coils. Prior to this invention, logging tools impressed currents into the formation by means of direct application of voltages from the logging tool electrodes. Over the next ten years, the induction log also became popular in wells drilled with fresh mud.

Interpretation of water saturation became more reliable because of reduced borehole effect on the resistivity measurements, compared to conventional electrical resistivity logs. To some degree, bed boundary effects were more predictable and compensated for electronically. The induction log has evolved considerably over its fifty year life and is the most common log run today.

FIGURE 1.04: Comparison of Electrical Survey (ES) and Induction Log (IL)

The laterolog was also introduced in 1948 - 1949. It was a multi-electrode electrical log designed to minimize borehole effects in salty drilling mud. Again, improved resistivity values led to better water saturation and porosity determinations, still using the Archie method.

The microlaterolog, to replace the microlog in salt mud, was first seen in 1952. Curve-shape analysis was not easy, but standard Archie methods worked well with this data. Other similar tools, such as the proximity log, and the micro-spherically focused log, are variations of the microlaterolog designed to improve shallow resistivity measurements in a variety of borehole conditions.

Neutron logs first appeared in 1938, but were not common until l946, when better sources of neutron radiation became more readily available. Neutrons emitted by the source, are absorbed by hydrogen atoms, which are common in water and petroleum. Qualitative interpretation of porosity (which contains water or oil) was possible by detecting the number of neutrons which were not absorbed but were scattered back to the detector. In some tools, the captured gamma rays created by the neutron bombardment were counted instead of the neutrons.

This was the first independent source of porosity information that did not rely on Archie's formation factor concept and the resistivity log data. The tool had, and has, its faults, but modern neutron logs are useful quantitative interpretation aids. Again, better detectors have increased the resolution and accuracy of the measurements. The modern version of the neutron log compensates for borehole size and a number of environment factors automatically.

The two-receiver acoustic travel time (sonic) log showed up in 1957. Laboratory work had demonstrated that the travel time of sound in a rock, after adjustments for fluid and matrix rock travel time values, was capable of estimating porosity. Thus, another independent source of porosity data was born.

M. J. Wyllie published an interpretation method for apparent porosity from the sonic log using the time average equation in 1956. It is one of the most common analysis methods in use. The laboratory work and relationships between porosity and sound velocity (or travel time) was exhaustively studied between 1940 and 1965. Much of the work was aimed at solving problems in seismic survey interpretations. Strangely enough, the Wyllie formula, for all its success over almost fifty years of use in log interpretation, can be shown to be physically incorrect in the laboratory and in theory for many situations, especially those involving compressible fluids such as gas.

The sonic-resistivity crossplot was invented shortly after the sonic log. It allowed visual as well as quantitative presentation of porosity and water saturation results on one piece of paper without the use of additional charts, nomographs, or slide rules (hand calculators had not yet been invented). It was tedious work, but thousands of crossplots were made during the sixties, and a few less progressive analysts still use them today.

FIGURE 1.05: Sonic-Resistivity Crossplot Interpretation for Porosity and Water Saturation

Quick look methods to differentiate hydrocarbon zones from water zones also followed the introduction of the sonic log. One such technique, the "Rwa Method", is still very popular. The principle used was to quickly calculate, from the Archie water saturation equation and the sonic log porosity value, the apparent water resistivity which would make the zone 100% water saturated.

If a particular value of water resistivity was considerably higher than the trend of many other values from above and below it in the borehole, then hydrocarbon could be suspected in the anomalous zone. No shale corrections were made, so shaly sands often showed poorly in this analysis.

Another quick look method is called the overlay method. The simplest approach was to overlay the resistivity log and the sonic log in such a way as to have the two curves fall on top of each other in the obvious water zones. Zones in which the resistivity log fell to the right of the sonic log were either potential pay zones or tight (non porous).

The overlay method was improved by generating compatible scale logs so that scaling differences did not cause false shows. The compatibility could be created by transforming the resistivity and sonic curves to apparent porosity or to apparent formation factor. This was done at the wellsite by appropriate function formers in the surface electronics, or back in the office by use of computer processing.

The invention of the logarithmic presentation for resistivity data, when the dual induction log was introduced in 1962, made quick look overlay methods even more popular and practical at the well site.

Many modern logs are designed to give good visual impressions of lithology, porosity, or hydrocarbon by means of compatible scale overlays. The density-neutron combination log is the most common example. The latest versions of computerized logging trucks even shade-in the separation between compatible scaled logs to emphasize the apparent prospective zones.

The density log was introduced in l959. It was another independent source of porosity data. With three sources of apparent porosity, (sonic, neutron and density), in addition to the resistivity methods, it was now possible to account for more variables. This led to crossplot or chartbook methods which compared the apparent porosity values from two sources, to help identify lithology (shale content or limestone - dolomite ratio, for example).

The sonic-density crossplot was common in the early sixties, with the density-neutron crossplot becoming more common in the late sixties, as the neutron logs became better calibrated and scaled in porosity units.

Since a crossplot is merely the solution to three simultaneous equations in three unknowns, the use of computers to solve these equations was a popular subject in the early sixties. Extensions of this concept to four, five or six simultaneous equations demanded a computer since graphical methods could not cope with the multi-dimensional aspect of the job.

FIGURE 1.06: Early Computed Log c. 1966

The desired results from such methods are porosity and the percent of each matrix rock type present. Usually one extra component can be found for each additional independent logging tool measurement used in the simultaneous equations. The method suffered if the list of unknowns in the equations did not match the real rock sequence. This can be mitigated, at least in part, by allowing the computer program to search for the best lithologic model.

Linear programming (simultaneous equations with constraints) was tried. It was not very successful, because knowledge of rock properties, the so-called known data, was not really very well known. As well, tool response to rock mixtures was not well defined.

The late fifties and early sixties also saw a great deal of work in atomic physics and both the pulsed neutron (or atomic activation) log and natural gamma ray spectroscopy log were described. However, suitable tools did not become available until 1968, and were not common until 1971.

The pulsed neutron log provides another apparent porosity evaluation, as well as an independent assessment of water saturation. The logs are also called thermal decay time logs, chlorine logs, carbon/oxygen logs or spectral gamma ray logs (note the lack of the word "natural" in this case) depending on the details of the source-detector systems and the rock properties derived from the data. They are usually run in cased holes.

The natural gamma ray spectrolog allows interpretation of uranium, thorium and potassium content in a formation. This is used to help segregate shale from other naturally radioactive rocks, such as uranium bearing dolomites or potassium rich sandstones. In conjunction with other log data, it can help define the types of clay minerals present in the shales.

The nuclear-magnetic resonance log was described in 1956. The theory suggested that effective porosity and permeability could be determined from the measurements. Good examples of this are still rare even after nearly fifty years of refinement- but Year 20XX versions of the tools will probably succeed. Unfortunately, the tool sees a very small fraction of the rock seen by other logs, so it may never be realistic to compare values from such dissimilar rock volumes.

Other methods for interpreting permeability, based on empirical relationships between porosity and water saturation had been presented prior to l960 and are still used today. Some examples are the Timur, Wyllie-Rose, and Coates-Dumanoir methods.

Prediction of abnormal pressured zones, and potential drilling or blowout problems, were developed from the various porosity estimating logs, beginning in l956. This was based on depth-trend line analysis of the sonic log primarily, although most logs, including density, neutron, and resistivity logs can be used.

The log types and interpretation methods discussed so far are all used in open-hole conditions, that is, after the well is drilled but before it is cased with pipe and cement, and finally completed to flow oil or gas (or heaven forbid, water). All the radioactive logs (gamma ray, spectral gamma ray, neutron, pulsed neutron) except density logs can be run in cased holes, and interpreted with approximate corrections for casing size and thickness.

Resistivity and older style sonic logs cannot be run in casing to obtain information about the rocks, although the sonic log is used to evaluate the cement behind the casing. Sonic wavetrain logs run through the casing are sometimes useful in evaluation of the rocks, but are most frequently used for cement evaluation. Recent versions of sonic logs use computer processing of the wavetrains to determine compressional, shear, and Stoneley wave travel times in both open and cased-hole situations. Resistivity logging through casing is also being developed.

Other logs, such as temperature, flow-meter (spinner surveys), gradiomonometer (a fancy name for fluid density meter), and noise logs are used to assist in interpretation of the location, amount, and type of fluid flow in producing or injecting wells. The tools and techniques have evolved gradually since l952, when the first serious effort was made to evaluate well performance with logging tools.

While the early years were clearly a period of invention of hardware and techniques, the middle years could be termed the period of understanding. Although significant new tools were developed, such as the sonic and density logs, the interpretation process required more formidable effort. Customers wanted more reliable answers along with the more reliable logging tools.

1.03 The Recent Years (1969 - 1985)
A major effort was made in the mid sixties to perfect water saturation interpretation in shaly sands. Archie's equation was not designed for this situation. Many competing methods were proposed, but the fallout left the Simandoux equation (about l965) with the Waxman-Smits method (l968) holding sway for a zealous few. Most of the methods, including Simandoux, suffer from lack of rigor or have a physically unsatisfying model. The Waxman-Smits method is theoretically acceptable but some of the data needed for the equations (such as cation exchange capacity of the rock) cannot be obtained from logs reliably. It is difficult and expensive to get from measurements on cores of real rocks, especially if there are no cores to be found from the zone in question.

Another approach is called the dual-water model (or bulk volume water method), published by various authors between l968 and l97l. It segregates the total amount of water in a formation into two parts - that bound to the shale (bound-water) and that in the pore space (pore water). The method is currently popularized in most service company programs, both in the office and on the computerized logging trucks at the wellsite.

Controversy still rages over the best water saturation method and the ultimate water saturation equation has yet to be presented.

Water saturation interpretation in shaly sands and porosity determination were both being studied in the late sixties. With several independent sources of data, and with more unknowns than measurements, a new style of interpretation was proposed. Instead of solving a fixed set of simultaneous equations, various iterative solutions were used to minimize the change in one or several computed results.

The primary goal was to correct for shale, light hydrocarbon effect, heavy mineral effect, and to solve for porosity and lithology at the same time. Success depended greatly on log data quality and on how well the calculation model actually fit the real geology. Much work is still being done in this area and new approaches appear in journals yearly.

FIG 1.07: SARABAND Computed Log c.1971 FIG 1.08: CORIBAND Computed Log c.1971

These models absolutely depended on high powered computers, digital data recording (first achieved in l965) and great patience, since results did not appear quickly. Weeks or months might be needed to get results for even a small group of related wells. This situation has improved markedly since 1985.

More advanced computer programs for carbonate rocks appeared in l97l to provide a similar service as was available for the shaly sand situation. The goal in this program was automatic hydrocarbon correction and mineral identification.

The best known examples of these programs are Schlumberger's SARABAND (superceded by VOLAN and ELAN), CORIBAND, and Dresser Atlas' EPILOG products. All these methods are iterative refinements of the crossplot or simultaneous equation solutions.

During the seventies and early eighties, these methods were programmed on low cost sophisticated hand calculators. If large volumes of data were required, desktop computers with digitizers, plotters and printers could be obtained from several sources. Today, the ubiquitous personal computer does the work at a fraction of the cost and time.

The first truly portable stand-alone desktop system that did not require connection to a large mainframe computer was LOG/MATE, developed by the author and D. W. Curwen in l976. This was 5 years before IBM "invented" the PC. It has since been mimicked and improved upon by many others, so that a wide range of such systems are available.

Timeshare systems using computer terminals to larger mainframes or mini-computers were first seen in l965, and are still used. Both batch and interactive time share systems can be found in many oil companies, service companies, and consulting firms. The phrase "time sharing" has disappeared from computer lingo but the concept persists with local area networks, UNIX servers, and distributed computing.

Log analysis methods vary from crude to complex and the quality of results varies with the knowledge and experience of the analyst. The quality and age of input data is always a problem to consider. Simpler systems, with a good analyst at the controls, often provide better results, because of the personal input and knowledge of the analyst. More complex programs tend to do unexpected things and are not easy to control, even by expert log analysts.

Moving the analysis from the office to the wellsite, to speed up decision making, has always been a driving force in interpretation techniques. Of course, all the manual methods described above could be performed at the wellsite, using charts and slide rules, and later with electronic calculators.

In l963, attempts were made to interpret porosity and water saturation automatically by recording the so-called moveable oil plot. This involved analog processing of log curves to obtain the appropriate data. How many readers actually know what an analog computer is?

FIGURE 1.09: CYBERLOOK Computed Log Analysis c. 1976

While digital recording of well logs began in l965, early trials of digital computation at the wellsite did not begin until l972. After this date, the major service companies have almost completely replaced all their older analog logging units. This provided both log interpretation and calibration control by computer. The best known interpretation examples are Schlumberger's CYBERLOOK and Dresser's PROLOG products.

A number of new tools, revised uses of older tools, and significant advances in computer processing of log data have been introduced in the 1980's, and are gaining rapid acceptance by well operators.

Satellite transmission of log data from the wellsite to service company computer centers superceded the Telecopier and FAX machine in many areas, allowing faster decision making at the head office, somewhat to the detriment of local autonomy and egos.

The lithodensity log is an improved density log with reduced statistical variations on the density measurement, and a new curve - the photo electric capture cross-section curve, better known as the PE curve. Its' value depends on the rock lithology and is relatively unaffected by porosity and pore fluid type. Therefore, it can be used to assist in lithology identification in simultaneous equation solutions.

The natural gamma ray spectrolog, mentioned earlier, is now also widely used to resolve lithology problems, such as radioactive dolomite or granite wash formations, or to help define clay types in shale. It provides three primary curves - the potassium, thorium and uranium curves, which when summed, give the total gamma ray curve. These three curves, plus the three porosity curves (density, sonic and neutron), and the Pe curve provide seven independent measurements of formation properties, which should allow a total of eight lithologic properties to be calculated from the data.

The three usual resistivity curves, the caliper curve(s), and data from the electromagnetic propagation log, which is presently being used to determine flushed zone water saturation, can be added to the list, for a total of 12 or more independent curves. It is clear that the solution mechanism is beyond chartbook and calculator capabilities. Most popular computer programs have been updated to provide specific hard-coded solutions for specific combinations of these tools and individual lithologic models. For example, Dresser lists eight different open hole and five cased hole programs to adapt to the changing times.

When one considers adding multiple passes of the thermal decay time log (pulsed neutron log) for each year of a well's life, the data explosion becomes increasingly difficult to cope with.

One product, called FACIOLOG, by Schlumberger, was an attempt to reduce this data overload to a minimum. It provides a detailed electro-facies log which, when calibrated to rock sample and core data, can be very useful in understanding depositional environments and well to well correlations. It can also be presented on a seismic time scale to assist in correlating normal seismic data, or vertical seismic profiles taken in the same well. Its’ visual appearance mimics the type of shading used by geologists while drawing their geological sample logs. Unfortunately, such interpretive log displays have not received wide acceptance.

Single well studies as described above lead directly to field and pool studies, seismic modeling, mapping, contouring, reservoir modeling and simulations which are topics not normally associated with well log analysis. Such studies are becoming commonplace, and are far more successful when the log data has been properly processed for the specific end-use, and integrated with all other geoscience disciplines.

A second approach by Schlumberger has been to create a universal log interpretation program, in which the log data suite, the lithologic model, and the log-rock response equations are provided by the user, instead of being hard coded. This product is called GLOBAL and can be classed as a linear programming solution. It has additional features which make it unique, such as a complete set of detailed environmental corrections, and a statistical evaluation section which attempts to minimize the inconsistency between input data sources and assumptions, and the interpretation model being used. The uncertainty in each input data value is also considered by the program. This approach is independent of the log interpretation model used which could be VOLAN or CORIBAND or any other model supplied by the user. Similar software is available now from several sources.

Another area of advance is in dipmeter interpretation, as more sophisticated computer programs provide more coherent data for evaluation of detailed stratigraphy and permeability direction. This is especially practical when combined with a product like FACIOLOG.

The nuclear magnetic log (sometimes called the unclear magnetic log because so few people understand how it really works) is also being pursued again for its ability to predict permeability, fluid viscosity, clay bound water, and irreducible water saturation.

These complex and expensive logging tools plus interpretation procedures have one thing in common - the capacity to improve oil and gas production if used properly. In order to reduce dependency on imported oil in Europe, USA, and Canada, it is necessary to exert this maximum effort on many wells. A minimum well evaluation effort is no longer considered a cost saving, but is instead an expensive loss of potential reserves.

The recent years in well logging can be termed the era of digital data, giving tool designers and analysts the power of the computer to bring to the surface more data of higher quality than ever before.

1.04 The State of the Art (1986 - Present)
The perpetual evolution of logging tools to improve data quality, signal to noise ratio, bed resolution, and depth of investigation demonstrate the gradual, almost un-noticed, changes in our industry. This will no doubt continue; but how far can we go, or want to go, is an open question. We may already record more data than we can conveniently use. The question really is: Is it the right data to give the answers we need.

The introduction of digital image logs and signal processing theory to log data are dramatic improvements that have fundamentally altered how we use logs, for example in quantifying fracture porosity and intensity or in evaluating depositional environment. What could be the next great leap is not at all clear. We have exhausted most of the available frequencies of the electromagnetic spectrum (except maybe the infra-red) and have tested most physical principles.

FIGURE 1.10: Evolution - Early logging truck, Modern truck (Schlumberger photos)

We have come a long way since the Schlumberger brothers put the first electrical log onto paper in 1927.

The incredible and unpredictable growth of other technologies outside our industry also has had dramatic effects. Low-cost high-speed computers, powerful spreadsheet and graphics software, satellite data transmission, and group work via local area networks or the Internet have changed the way we do our work. The massive increase in data quantity brought about by these technologies threatens to overwhelm us, since training, corporate infrastructure, and management style can barely keep up. How much faster can computers run ever more complicated software with ever larger data sets?

To give you a sense of the progress in computer-aided log analysis, I wrote my first program in 1963 on an IBM 1401 computer to solve mineralogy and ore grade in the potash fields in Saskatchewan. The computer filled a room the size of a small assembly hall and the program was about 100 lines long. Later, I programmed a desk-sized computer (an IBM 1130), then more room sized beasts (EMR 6050 and CDC 3300). In early 1976, I recognized the need to pursue a small portable solution, and after evaluating several rack mounted industrial machines, I settled on a desktop calculator/computer, the HP 9825. This became the first commercial log analysis system on a desktop - LOG/MATE, five years before IBM “invented” the PC. By the way, the original HP 9825 had only 4 Kilobytes of memory and the floppy disc held only 256 K. It cost 10 times more than today’s 2 GHz machine with 128MB memory and 40GB hard drive! We have clearly made progress here too.

So, let's take a look at what is new and developing in our field that will benefit the oil and gas industry. Three buzzwords summarize the current state of the art in well log analysis - imaging, resolution, and integration. Let’s look at these in turn.

Two logs provide a more or less complete image of the rock on the wall of the wellbore. One is the formation micro-scanner or micro-imaging log, a super-micro, multi-electrode, multi-pad resistivity log, an offshoot of the dipmeter tool. The log appears similar to a photograph; low resistivity is shaded a dark colour, high resistivity is white. The shading between colours is cunningly chosen so that stratigraphic features can be seen, usually with better resolution than can be seen with the naked eye on real cores. Fractures and bedding planes, along with their dip angle and orientation, are readily identified. Image enhancement software similar to that used for air photos can be applied to help bring out subtle detail.

This log also leads in the resolution category; it can visualize fractures of only a few microns in width. Further numerical processing leads to quantitative assessment of fracture intensity, fracture aperture, and fracture porosity. These results emphatically debunk much “conventional wisdom” regarding fracture aperture and porosity.

The second tool that gives a real image log is the acoustic imager, often called a televiewer log. It uses a rotating head that emits and receives an acoustic signal. Both sound amplitude and sound traveltime are recorded, giving images proportional to acoustic impedance and borehole diameter respectively. Resolution is lower than the micro-scanner, although most significant bedding events and fractures can be seen in well consolidated formations. The log can be enhanced in image processing software.

To capitalize on the imaging concept, newer versions of the induction log, laterolog, and sonic log are presented in an image format as well as the usual wiggly curve format. The resistivity log image from the azimuthal resistivity log (a form of laterolog) is a coarser resistivity image similar in appearance to the micro-scanner. The azimuthal resistivities are very helpful in horizontal wells as curves looking upward into shale or tight cap rock or downward into a water zone can be isolated from the horizontally aimed curves.

The array induction log presents 5 resistivity curves of 5 different depths of investigation, as well as a coloured map of these values. This aids interpretation of invasion profiles. The measurement of vertical resistivity is being field-tested and this will aid in solving thinly laminated reservoir problems.

The array sonic and dipole shear sonic logs offer the usual three acoustic log curves, recorded at a multiplicity of spacings if desired, as well as a colour image of acoustic wavetrains. This allows visualization of the changes in amplitude and arrival time of the three acoustic waves and emphasizes interference patterns that indicate fractures.

Where can image logs go in the future? I hope “everywhere”! To do this, logging speed will have to increase and costs will have to drop. An article in Hart’s E&P magazine states that one-third of the world’s oil is locked up in low-resistivity laminated shaly sands. The high resolution of the micro-scanner and televiewer are the only logging tools available to determine net sand in this environment. Look forward to this revolution and be prepared to pay the price for logging, processing, and interpretation that comes with the huge data volumes.

FIGURE 1.11: Image logs - Microscanner, televiewer, resistivity (saturation profile)

The last three tools described above also qualify in the thin-bed resolution sweepstakes, as they attempt to resolve beds to about 1/3 the thickness of previous tools. Combined with thin bed processing of the newer density, neutron, and gamma ray logs, we are now able to obtain more accurate porosity and water saturation in beds as thin as one or two feet instead of the more usual three to six feet. Unfortunately, little can be done for older logs that already exist in our file cabinets. The thin bed processing available today requires high density digital recording and this cannot be extracted from earlier data files or paper logs.

Unfortunately, high resolution logs look noisy. Many are filtered “to look nice”, this is a tremendous waste of data. In 1967, I delivered some of the first deconvolved seismic sections in Canada to a client. He was horrified because the data looked so noisy. Where would seismic processing be today without deconvolution? I have always been amazed at how slow the well logging companies have been in applying decon to log curves. Now, if we could just get them to square up the bed boundaries!

FIGURE 1.12: High resolution - Sonic wavetrain, microscanner, nuclear magnetic resonance

High resolution and imaging logs also require excellent borehole conditions. Management must ensure that drilling and mud engineers are part of the team.

These logs provide more megabytes of data than ever before. Fortunately, computer speed, memory size, and data storage capacity of modern desktop computers have kept pace with this development. Hardware costs are much lower than fifteen years ago. However, log analysis software costs are higher than ever, partly because the software does more than it ever did and partly because we demand such attractive screen and printer images. The larger integrated software packages are ill-suited for casual users, so there is still a strong need for small easy-to-use packages. Lower borehole signals, stronger signal sources, more sensitive receivers, and signal summation techniques will continue to improve resolution at a steady pace.

Integration means the cooperation and interchange of ideas, data, and results between the various geoscience disciplines involved in a pool study or reservoir simulation. Integration means that all team members have a common understanding of what the logs and log analysis indicate. Feedback between each group forces iteration and refinement of all results.

I am still asked to review projects where the log analysis has not been compared to core analysis, well performance, or sample description! I call this type of review a “Forensic Log Analysis”. It usually involves an autopsy, or at least major surgery, to find out what went wrong. Re-computation is inevitable when log analysis is done in isolation from the other disciplines. There is no point in performing a “Blind” log analysis; this is merely data processing, without ground truth control. As some of you may know, I am legally blind, so maybe that is why I am so sensitive about this issue.

Integrated projects require an extraordinary effort in communication between team participants. Many professionals are not good communicators; we talk a good line but we don’t listen well. Turf wars, ego, and seniority must be put aside. Team leaders must be adept at locating barriers to good communication. Team members must be willing to give up some independence in order to give and receive the knowledge needed for a successful project. This is never easy and I predict that there will still be many reservoir description failures caused by poor communication, not by lack of data or lack of effort.

Integrated exploration, development, and simulation software is readily available. This helps to share data and results, but does little to help share understanding unless those good communication skills are present.

Another form of integration is also taking place - corporate merger and acquisition by both logging service companies and oil exploration companies. The three major well logging service companies now have most field services (logging, testing, cementing, etc) tied up under one roof, and have added geophysics, geology, engineering, simulation, production, and management services and software to offer one-stop shopping for the resource owner. They are now offering to run complete oil field operations from discovery, through production, to field abandonment.

FIGURE 1.13: Integration - Project planning and implementation

It will take a major change on the part of the resource owner to monitor the performance of such a service. Instead of doing the work in-house, they will have to check and monitor others and request changes or improvements in performance. These are roles that many professionals are not ready for, so training and corporate infrastructure will have to change dramatically. The changes will have to be made well before such contracts are given out. Unless a resource owner is ready for contract development, I predict some very unhappy scenarios.

Finally, we should mention the Internet as an integrating as well as a liberating force. Databases are more easily accessible, results and reports can be transferred by email, and much work can be done away from the corporate office environment. Soon, major application software and technical learning centers will be widely available on the Net. I currently receive and deliver the vast majority of my work over the Internet. Although it is always nice to have face-to-face meetings with clients and co-workers, it is not necessary to over do it. Many professionals complain that they spend too much time in meetings. Group work or consulting via the Internet reduces the need for many meetings.

Electronic mail beats “telephone tag” and gives a permanent record of what was really said. I see a great future for remote group work. The only perceived snags are data security and loss of control over employees, but these are capable of solution with a little effort.

There are other areas of petrophysics where change will certainly occur. Controversy still rages over the best water saturation method. The ultimate water saturation equation has yet to be presented. Maybe some one in this audience will develop the perfect equation.

The nuclear magnetic resonance log dominates the technical papers submitted at conferences. After 30 years of development, the tool is just reaching adulthood. Customer resistance to previous hyperbole will gradually disappear. However, the small rock volume seen by the tool will continue to make it difficult to integrate this data with conventional logs. Some people see this tool as a panacea for all that ails conventional log analysis. This just isn’t true. For example, a claim is made that the NMR porosities are independent of lithology, yet the T2 cutoffs that determine porosity vary with lithology.

FIGURE 1.14: NMR pay in high SW environment, NMR porosity and permeability vs core

Geostatistics to predict petrophysical rock properties away from the well bore is growing in popularity. Good software exists and some successes have been published. Further integration of geostatistics with seismic attributes and seismic petrophysics is in its infancy. Lack of training and expense are the current holdups to more widespread use.

Seismic petrophysics, especially with long offset spreads, is on the rise. Again, 30 years have passed since seismic inversion was first practical and we are just now getting close to real petrophysical properties. Again much training is needed, since many practitioners seem to forget that sonic and density logs see an invaded zone and the seismic signal does not. How much longer will it take to learn this simple truth?

FIGURE 1.15: Geostatistical porosity distribution map, AVO seismic model from log analysis

We cannot ignore the tremendous strides in Logging While Drilling. Most conventional open hole measurements can be made near the bit, before invasion becomes too serious. Even the NMR is in an LWD test program. More deviated, deeper, hotter holes will require this technology. Reservoir description is enhanced because of the immediate acquisition of data and the reduced invasion profile.

Cased hole logs for reservoir description, completion integrity, and fluid flow evaluations are much enhanced over previous efforts. Casing, tubing, and cement image logs are readily available but seldom used to their full extent in solving well performance problems. Production logging is underutilized in remedial work. When they are run, interpretation skills are weak, especially in deviated, multi-phase flow. There seems to be no concerted effort to correct this lack of training.

With favorable cement bond, most open hole measurements including sonic, density, and resistivity, can be measured through casing. The resistivity log is being field tested by the major logging contractors as we speak here today. It’s about time- an independent Canadian company offered such a tool over 25 years ago. Not all that is new or useful comes from the major research centers; the “little guy” has an important role to play. NMR and highly focused induction logs both came from outside our industry and were pioneered by small independent research labs. Although I have no idea what the next important advance will be, it is likely that it will come from an unrelated field.

The state of the art in log analysis software has advanced significantly. In deterministic models, we have seen tremendous strides in the ability to handle user-defined algorithms and user-defined displays of results. Gone are the days of inflexible, hard-coded math that doesn’t quite suit the rock sequence. Such systems allow competent users to experiment with new ideas, add new log curves as they are invented, and present their own images to management - all this without re-writing the underlying software. We no longer have to “lie to the computer” or modify results outside the program to obtain rational results. These programs also have enhanced core handling capabilities, as well as annotation and reporting features, such as sample description and mud/gas log integration.

The multi-mineral and probabalistic models available today are more robust and the underlying tool responses are better known and more linear. It still takes considerable effort to tune the models for a particular rock sequence, so they are not a cure-all or an “automatic” log analysis solution. Other forms of data reduction, such as principal component, multi-variant, or least-squares regression analysis are also more practical, mainly due to faster computers and software packages that are easier to use.

Integration of deterministic models and user-defined algorithms with probabalistic or other hard coded models is not well developed. We are still forced to run these disparate models in relative isolation from each other, with the analyst left to iterate between them. By adding expert system and fuzzy logic concepts, I expect that these program designs will gradually be merged into a coherent whole. Software that incorporates neural network code may already be aimed in this direction. Unfortunately, I have no personal experience with neural network products, so I can’t vouch for their success.

There is much happening in our field. Petrophysics is changing. The uses of petrophysics are changing. We will never be out of work!

In the face of continuous change, humans yearn for consistency. We normally resist change and strive instead for the traditional approach. Unfortunately, we will never optimize oil production this way. We must learn to accept the challenge of change, adapt to it, and in fact, lead the charge by innovation and invention of new solutions to the problem of data overload, complex reservoirs, and working with multi-discipline team members.

1.05 Log Interpretation in the Future
The future? It will probably involve artificial intelligence - the darling of the academic world in the 1980’s. Computer based expert systems will learn from experts in the field of log analysis, and will subsequently advise and consult with less expert users. As the expert system is increasingly used, its cleverness will heighten, until it is more intelligent than any single expert. Such hardware and software already exists, albeit for much simpler situations than log analysis. However, it is known that major service companies, oil companies, and consulting firms have embarked on research in this field, emphasizing log interpretation.

The success of a log analysis is judged by how well the analysis predicts the future performance of the completed zone. Many analysts and their managers are unaware whether their results were good or bad. Artificial intelligence with a learning data base, should provide the kind of "perfect memory" and the unbiased question/answer sequence needed to keep track of success and failure.

Hopefully we will learn how to do better work as time goes on, by studying the background to each success or failure, monitored automatically by the expert system.

The future holds the promise of a long sought goal in well logging - an automatic, universal interpretation program that never fails and adapts to change. Of course, this is just a dream, right?

Twenty years have passed since the above was written and neither prediction seems any closer to fruition. What happened to all that research effort and all those prototype systems?

1.06 A True History of Oil and Gas Development
The traditional view of the oil industry is that it started in the USA in 1859. Not true, I'm afraid.

The oil seeps at Baku (in present-day Azerbaijan) flowed freely centuries before year 1. They played a major role around 600 BC in the Zoroastrian religion of Persia and India. Uses of petroleum are mentioned in the Old Testament of the Bible. Chinese and Japanese writings that predate the first millennium by as much as 900 years describe the use of natural gas and oil from natural flows, seeps, and hand dug wells. Credit for the first drilled oil well goes to the Chinese in the year 347 BC.

Sumerians burned oil in pans for lighting as early as 4500 BC. Oil lamps appeared around 500 BC. A town near Grenoble France had natural gas street lamps in the year 100!! Oil streetlights appeared in Cordoba around 900, London in 1414, and Paris in 1524.

Sir Thomas Shirley presented a paper to the Royal Society in 1658 on natural gas flows in Britain. In 1739, V.I. Veitbrecht published an article "About Oil" in the Russian scientific magazine "Primechaniya na Vedomosti" where he described the Baku area oil wells and provided a plan of the oil and gas fields. This may be the first technical paper with a reservoir description.

Coal-gas (manufactured gas) dates back to 1726 in England. Oil was extracted from oil sands in Pechelbron France in 1735. Creation of coal-oil by distillation of coal and oil shales occurred between 1781 and 1820 in England, France, and Germany.

In 1626 Joseph de la Roche d'Allion, a Jesuit priest from France based at Trois Rivieres in Quebec, reported oil seeps in what is now New York state. Peter Pond was the first non-native to report the discovery of oil in Canada in 1778 at the Athabasca oil sands in northeast Alberta.

A Canadian, Dr. Abraham Gesner, developed the distillation of kerosene from crude oil in 1846. Kerosene helped reduce the use of whale oil for illumination. Some claim the whale oil problem had already been overcome by manufactured gas and oil from coal, but the two events certainly helped the "Save the Whales" campaign. The Americans give Benjamin Sillian credit for the invention of kerosene in 1855, but he was at least third in line after Gesner and a Polish druggist named Ignacy Lukasiewicz (1853). Coal-oil and kerosene are the same product - just different sources.

Azerbaijan claims the first drilled well in the modern era at Bibi-Heybat, a suburb of Baku on the Caspian Sea, in 1846. The first drilled oil wells in Europe were located near Bucharest in Romania in 1857 but Poland makes the same claim for 1854 at Bobrka.

The completion of the first commercial oil well in North America occurred in 1858 at Oil Springs, Lambton County, Ontario and was quickly followed by more oil at Petrolia, Ontario. The man's name was James Miller Williams. This was a hand dug well and the first drilled wells came in 1862. Some of these flowed up to 7000 barrels per day, often before anyone thought to build a storage pit or tank. Some of the early oil flowed down creeks to be wasted in the Great Lakes, but it had been doing that for eons before, from natural seepage.

There was an Oil Springs and a Petrolia in Pennsylvania too, but these wells came a year later (Edwin Drake, Titusville, 1859). There's a Petrolia in Texas, and another in California, not to mention the park in Baku set up by the Nobel brothers. It gets confusing.

It would appear that Drake's well placed the USA sixth in line in the sweepstakes for the first oil well, after China, Azerbaijan, Poland, Romania, and Canada. Drake's well, drilled to a depth of 69.5 feet, pumped oil at the inconsequential rate of 8 to 10 gallons a day. Some historians claim this is the USA's first commercial oil well. Drake himself never drilled another well but his discovery started a drilling rush in the area. His derrick burned down a few months later, killing nine men. He became an oil buyer and then a stock broker on Wall Street specializing in, you guessed it, oil stocks.

1.07 History of Oil and Gas in Canada
As noted earlier, Peter Pond was the first non-native to report the discovery of oil in Canada in 1778 at what is now the Athabasca oil sands. Canada's first commercial oil wells were found in Oil Springs and Petrolia, near Sarnia, Ontario, in 1858, a year before Edwin Drake's discovery at Oil Springs (Titusville), Pennsylvania. Both the Oil Springs discoveries were known before these dates from flowing seeps.

The subsequent development of Canada's first petroleum complex at Petrolia is a little known part of the industrial saga of the oil industry. Canada's chemical valley in Sarnia traces its ancestry directly to this area. During the period 1861 to 1897, nearly the entire requirement of Canada for crude, lubricants, waxes, kerosene, gasoline, and a widening range of chemicals for food, medicine, and industry was produced here. From 1863 to 1870, Canada was a major exporter of crude and refined products to the United States and Europe.

The contribution that Canadians made to the world's petroleum industry during the same period is even less appreciated. Men trained in the production, transportation, refining, and administration of this new resource, took their knowledge and skills to every corner of the world, opening many of the great oil fields that are still major suppliers of crude. They laboured on every continent in a hundred different countries. And the tradition continues to this day.

For more on this topic, look at "Hard Oiler! - The Story of Early Canadian's Quest for Oil at Home and Abroad", by Gary May, 1998, Hounslow Press, ISBN: 1550023160. "Petroleum in Canada" by Victor Ross, 1917, Southam Press gives a similar and more contemporaneous view.

New Brunswick achieved commercial production at Stoney Creek in 1884, although it was pretty minor by early Ontario standards, and these wells continued in production until modern times. Quebec, Prince Edward Island, onshore Nova Scotia, and onshore Newfoundland never found commercial quantities of oil or gas.

The first gas well in Alberta was drilled in 1883 at Alderson (then known as Langevin Siding), near Medicine Hat, by the Canadian Pacific Railway. They were, of course, looking for water. This well struck gas, caught fire, burned down the rig injuring one man who had to jump off, and was abandoned. A second well, the following year, again struck gas (it was only 8 feet away from the first one) and produced off-and-on for about 40 years. These, and similar wells, came to the notice of the Canadian government.

Dr. George Dawson of the Geological Survey of Canada, collected information on the wells at Langevin Siding and others, and presented a paper to the Royal Society of Canada in May, 1886. The paper was called "On Certain Borings in Manitoba and the Northwest Territory". The paper contained detailed sample descriptions of the wells - possibly the first "well logs" in Western Canada.

FIGURE 1.16: One of the first well logs in Western Canada
from Proceedings and Transactions of the Royal Society of Canada for the Year 1886 Volume IV.
Glenbow Archives

By the early 1890s several more wells had been drilled in the Medicine Hat area, producing gas for homes and factories. Rudyard Kipling, on a visit in the early 1900’s, admitted that he liked Medicine Hat but "It has all hell for a basement!"

By 1908, development of the Bow Island gas field led to the first pipelines to deliver natural gas to Alberta communities. Construction of a 16-inch pipeline from southwest of Medicine Hat to Calgary began in April 1912 and was completed in only 86 days. A second leg reached Lethbridge in July the same year. This was spearheaded by Eugene Coste, Canada's first natural gas engineer. He had discovered the first commercial gas well in Essex County Ontario in 1888.

The Alberta oil boom didn't begin until 1914 with the drilling of Dingman #1 near Turner Valley. A replica of the drilling rig lives at Heritage Park in Calgary. This wet gas success started a stock market flurry that died less than a year later with the loss of most of the investors' money.

The well was the precursor for the deeper zone discovery drilled ten years later. Royalite #4 put Turner Valley on the oil and gas map for real.

In 1919, Imperial Oil geologist Ted Link, a crew of six drillers and an ox named "Nig" made a six-week, 1200 mile journey northward by railway, river boat, and on foot to the site now known as Norman Wells NWT, along the Mackenzie River. The ox helped to build a log house and put the drilling rig in place before being butchered to provide food for the winter. Drilling resumed in the spring with the world's most northerly oil discovery coming in August 1920.

Between 1920 and 1947, there were a dozen or so significant oil discoveries in the Cretaceous of Alberta, but no "elephants", and nothing very deep. Vern Hunter drilled Imperial Oil's Leduc #1 Devonian oil discovery in 1947, ending a long dry spell in the Alberta search. Although minor shows were found much earlier, 1951 saw the first commercial oil discoveries in Manitoba and NE British Columbia, followed by Saskatchewan 1953. Over the next 20 years, Canada became self sufficient in oil and gas.

As early as 1921, Dr. Karl Clark pioneered the extraction of oil from tar sands by the hot water process. He built pilot plants in 1930 at Clearwater and in 1949 at Bitumont under the auspices of the Alberta Research Council. Great Canadian Oil Sands Ltd (later Suncor) began production of the Athabasca tar sands north of Fort McMurray in 1967. Shell drilled offshore British Columbia that year, but found nothing. A few years later, the BC Government placed a moratorium on further drilling that has not been lifted.

On the other frontiers, hydrocarbons were found offshore Nova Scotia (gas at Sable Island, 1967, oil at Cohasset, 1973), offshore Newfoundland (oil at Terra Nova, 1984), offshore in the Beaufort Sea and MacKenzie Delta (gas at Taglu, 1971, oil at Amauligak, 1978), onshore and offshore in the High Arctic Islands (gas at Drake Point, 1969 - oil at Bent Horn, 1974). It took between 20 and 30 years for some of these to come on-stream, and Arctic gas is still shut-in.

Note: Historical photos from websites listed in Bibliography.

1.08 History of Well Logging in Canada
The history of wireline well logging in Canada begins in 1937, a mere 10 years after the very first electric log was run in the Pechelbronn oilfield in France on September 5, 1927. A quote from the official Schlumberger history tells the story: “In another part of the country, a young engineer named Bill Gillingham was attempting to raise some interest in electric logging in the Bradford, Pennsylvania area. The response was not immediately tremendous. A trainee under Gillingham, R.R. Rieke, was told to head west by northwest, to Mt. Pleasant, Michigan, embarking on one of the strangest Schlumberger journeys you’ve heard of.”

You see, they ended up in Canada, not looking for oil, but for gold. The preliminary work had been conducted by Andre Allegret and, as a result of surface exploration, a contract had been let. “When we arrived,” Rieke said, “trouble was afoot. They had found gold alright, but not where the survey had said. When they drilled there - nothing. We left rather quickly.”

Two years, later, “electric logs” were introduced to the Canadian oil patch in 1939 by the forerunner of today’s Halliburton Services Ltd.

FIGURE 1.18: Early Halliburton Logging Truck c. 1946

The first Halliburton unit was operated out of Black Diamond, Alberta by Jack Pettinger, who remained active until 1979. Jack and another pioneer, Stan Nelner, currently with Halliburton in London, England, recalled that trips of hundreds of miles to such far-flung wildcat sites as Kamsack, Saskatchewan, Pouce Coupe, B.C. and Lloydminster were not uncommon.

During the war years, equipment was also stationed at Norman Wells on the Canol Project and at Vermilion, Alberta.

FIGURE 1.19: Showing Off at 55 Below Zero c. 1957

The logger of those days had to be versatile because he was often called upon to operate cementing and acidizing equipment, or run drill-stem tests, in addition to the standard electrical survey (ES). With increased demands after the Leduc discovery in 1947, more modern survey equipment was added. Also, the “FM” (frequency modulated) system of transmitting sub-surface data via a single conductor cable was adopted by Halliburton. This technique remained a unique feature of the Halliburton-Welex wireline equipment for many years.

The approximate dates of first availability of modern logging methods, as recalled by Gerry Obermeyer, a manager of operations for Halliburton, were Focused Resistivity 1952, Radioactive 1954, Induction 1954, and Acoustic 1958. A shift in the development of Canadian operations also occurred in 1957 when the parent company purchased WELEX Incorporated. A combined WELEX-Halliburton Electrical Well Section operated in Canada as a separate company for some time. The perforating service, which had also been introduced to Canada by Halliburton in 1940, was expanded. Later, that group was absorbed as an operating division of Halliburton Services Ltd.

Schlumberger arrived permanently in Canada in 1946 by opening a location at Lloydminster, manned by such notables as Ed Burge, Hugh Gough, and Arne Thorson. Truck numbers were in the 200 series.

FIGURE 1.20: Early Schlumberger Truck c. 1949

One of the older units in Canada about that time required that the crew jack up the rear end and install a chain from the rear axle to the winch drive. Services offered were ES, six-shot sidewall core guns and bullet perforating.

By 1949, there were offices in Calgary and Edmonton, and Neil Collins was at the helm in booming Redwater. Barry McVicar had joined the forces as well. By 1951, tools available were ES, gamma ray, dipmeter, directional, cores, microlog, laterolog, limestone device, temperature, perforating and caliper. The year 1951 also saw the introduction of revolutionary armoured steel cable to replace the 1 inch diameter fabric-covered line known as the “ragline”.

A job report of that year mentions a trip to a well near Fort Vermillion that commenced the 26th of April and ended June 29th, with most of the intervening time spent attempting to get to the well by building bridges and barges, waiting for ferries, and sinking into mud. Ten years later (1961) saw the first logs to be run in Canada’s Arctic Islands at Winter Harbour on Melville Island. Since that epic event, operations have taken place in all the frontier areas from the misty Queen Charlottes to Hudson’s Bay, The High Arctic Islands, the East Coast, and the Beaufort Sea.

Lane-Wells established their first office in Edmonton on the Cooking Lake Trail in 1947, offering the usual GR log. They quickly opened stations in Stettler, Virden, Swift Current, Estevan, Drayton Valley, Red Deer, Swan Hills, and Fort St. John, the hot spots of the time. The early managers were Bill Ludwig, Lee Lobdell and Glenn Robinson.

Perforating Guns of Canada Limited opened their first office in Edmonton on Calgary Trail in 1949. Walt Minor and Bill McKay were the people in charge. In the early 1950’s radiation logging for cased and open hole was one of the primary services available, out of the usual towns such as Lloydminster, Kindersley, Stettler, Estevan, and Drayton Valley. In 1965, the name was changed to Pan Geo Atlas Canada Limited and open-hole logging services were introduced in the following year.

In July of 1968, PGAC and Lane-Wells merged into one larger operation under the auspices of Dresser Atlas Inc. The combined companies offered a full line of services from various Canadian locations thereafter. Still later, Baker Hughes took over the entire Dresser complex, with the logging division becoming Baker-Atlas.

McCullough Wireline Services were around in the early 50s and offered services mainly in the cased-hole field. Mart Kernahan, one of the early managers, became better known for his contribution to the early days of computed log analysis at Computrex Computer Services Limited