ROLE OF PETROPHYSICS and INTERACTIONS
Petrophysicists offer services in the areas of well logging supervision, log analysis and interpretation, integration of log data with lab data, computer analysis of logs, seismic modeling, synthetic seismograms, and reconciliations of log data with geological, geophysical and exploration prospects, field studies and simulations, reserves estimates, and submissions to regulatory agencies.

These services are essential functions in modern oil and gas companies and cannot be accomplished without input from trained petrophysicists. The financial health and long-term success of a company depends on the central role of the petrophysicist in all aspects of the company’s exploration and development activities.

Log analysis often requires some numerical exercise, especially with the use of computers and calculators so common, but interpretation and judgment calls are required from the analyst as well. The job is not just to do the algebra, but, to decide what the numbers really mean. Will the well produce oil, or gas, or water, how much, and for how long?

Mr. G. E. Dawson-Grove, a well-known consulting petrophysicist, likens the role of the log analyst to that of the "spider in the web." He claims that the petrophysicist plays a "vital, central, potentially controlling position." The range of his or her influence is wider than any other discipline within the oil industry, with the possible exception of the financial wizard. To be successful in this role, however, the analyst has to realize the importance and potentially powerful position he or she is in, and be able to sell ideas to co-workers and management.

Because of the multi-discipline approach required, the analyst must maintain a web of communication with many seemingly unrelated functions within the organization. The analyst must be sensitive to the vibrations coming along each strand of the network and respond accordingly. That response might be in the realm of geophysics, geology, reservoir engineering, petroleum economics, secondary or tertiary recovery engineering, or corporate management.

"D-G" goes on to explain that we should not consider a response which suggests the minimum effort needed to get an answer, but should emphasize the maximum contribution that a petrophysicist (and all the available tools and data sets) could make to a company's success. We must convince management that a "full evaluation" is necessary, not just the minimum. There are selfish reasons as well as altruistic ones to pursue this route. You will look good if your company's success ratio looks good - especially if you can show how your contribution helped.

 

JOB DESCRIPTION - OFFICE DUTIES
A petrophysicist has many and varied duties. In the office, all of the following could cross your desk:

1. Design optimum logging programs, considering the objective formations, fluid characteristics, and company budget.
2. Supervise computer analysis of new and old wells to obtain maximum reconciliation of log data with cores, drill stem tests, and geological sample descriptions, using an in house system or commercial service bureaus as required.
3. Control quality and turnaround time of computer analysis jobs
4. Analyze dipmeter, production, and fracture identification logs.
5. Analyze logs, by hand or by programmable calculator, when computer analysis is impossible or inappropriate.
6. Co-ordinate log analysis for integration into reservoir evaluations, reservoir model studies, or geophysical prospects.
7. Undertake special research or in-depth studies of particular problems, such as over-pressure, variable log evaluation parameters, or exotic minerals.
8. Evaluate logs for ground water, coal, potash, salt, tar sands, uranium, or other valuable resources.
9. Prepare and present log evaluation courses for general or detailed study by oil company personnel.
10. Prepare detailed seismic models from well logs in conjunction with stratigraphic or structural assumptions, and create synthetic seismograms for each model using a computerized system.
11. Attend well completion, drilling location, partner, and progress meetings.
12. Supervise logistics of logging, coring, testing, and lab operations.

 

JOB DESCRIPTION - COMPUTER RELATED DUTIES
Using the petrophysical software package, duties could include any of the following:

1. Digitizer, magnetic tape, or keyboard data entry of raw log data.
2. Edit data (re-scale, depth shift, point edit).
3. Enter and edit analysis parameters.
4. Permanent storage of data on disc or tape.
5. Prepare neat, printed results with input data and computed data.
6. Prepare porosity and hydrocarbon volume accumulations with or without cutoffs – detail or summary listings.
7. Handle metric or English units logs with equal ease.
8. Provide many different log analysis methods, with user defined options, the choices depending on data quality and formation characteristics.
9. Prepare four or three dimensional crossplots with X, Y, Z and W axes and scales defined by the user.
10. Display versatile and highly selective plots of results or input data or both, in colour.
11. Input, edit, averaging, printout and plotting of core and mud log data and calibration of core and mud log data with log curve data.
12. Create reservoir summaries sorted by zone, project and cutoff levels.
13. Provide seismic data results (e.g. acoustic impedance, velocity, integrated time or density) printed or plotted.
14. Prepare seismic model studies, including effect of hydrocarbons and changing lithology.
15. Prepare synthetic seismograms on original or modeled data, with variable wavelet type and frequency, and create synthetic seismic section.
16. Provide fast turnaround, typically two hours for one zone less than 300 feet thick. (Less time per zone can be spent for multi-well or multi-zone projects). Time will depend on log quality and type, availability of other data, and whether or not that data is contradictory.

 

JOB DESCRIPTION - FIELD DUTIES
Although travel to the field is less common now than in earlier times, here is a list of possible tasks:

1. Get to the rig on time.
2. Prepare for the job by studying prior work before arrival, and by studying the sample description, DST reports, core descriptions and well history after arrival.
3. Discuss well history and results to date with wellsite geologist and drilling engineer.
4. Prepare instructions for the logging engineer as thoroughly as possible, based on logging program in well prognosis.
5. Discuss job details with logging engineer, explain your special requirements, why you are there, and what you expect from him.
6. Monitor progress continually; check films, repeats, scales, calibrations, logging speeds, depth control, keep records of tool failures, logging times, hole problems. Do not rely solely on the logging engineer's data, opinions, or service order information.
7. Monitor logistics, tool movements, hot-shots, time commitments (aircraft, land sales, etc.).
8. Keep wellsite geologist, wellsite engineer, and drilling supervisor informed on progress and problems, and keep logging engineer informed of changing requirements and time commitments.
9. Do log analysis based on all available data. Recommend interesting intervals for testing, recommend additional logs if analysis or log quality demands more data.
10. Report log analysis by radio or phone to oil company home office, report progress and next moves to your office via oil company contact or directly if radio or phone time is available.
11. Monitor re-plays, film assembly, and field printing of logs.
12. Write final reports, fill in all appropriate quality control forms, and log analysis report forms.
13. Collect all films, tapes, and prints. Package for hand delivery to client office, or arrange for air or courier delivery of logs to oil company office (or to partners as requested). No prints are to be left with logging engineer unless authorized by the client.
14. Monitor and recommend parameters for computerized field interpretations by the service company, if this has been requested.
15. Set up zones for computer analysis. If required make an extra set of logs for this, to be returned to client with final computerized analysis.
16. Go to next job (or home), submit reports to your office for typing, or finish report and email to office.
17. Check final typed report and deliver to client personally (if possible).
18. Request log repairs, in writing, from service company, or relay requirements to your office.
19. Request service company computed log (if required), Supply parameters and quality control intermediate results (or delegate to your office staff).
20. Supply copy of quality control report to service company sales engineer and to service company location manager.
21. Follow up results and recommendations with client.
22. Check logging contractor's service order for correct and complete details. If you have signing authority, sign service order and note discrepancies or disputes for future handling.
23. Review final invoice from service company. Compare to your own record of the job and request corrections or approve for payment.


Flow of data from the wellsite through to final analysis and interpretation. Note the
integration of offset data, core, DST and regional knowledge to calibrate the results.

These duties are highly variable over time and new situations occur at a moments notice. Be prepared!
 

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