What is the Role of a geologist in petroleum industry?

Answer 1

The role of a geologist varies not only with his area of specialization (there are numerous) but also experience earned on the job and the occupational specialties as described by the company for which he works. In general and traditionally, the geologist has been responsible for the exploration and delineation of the petroleum reservoir. Historically in the field the geologist would find and sample potential source rock and potential reservoir rock. He would map potential structures that could be petroleum traps and define where best to drill. Today, the lines are more blurred. The geologist can still be responsible for collecting rock samples in the field, but this might also be carried out by another geologist in a core lab examining core samples from another well whose samples correlate with the new area of interest. The gross surface structure of an area might be mapped by a geologist in the field but more likely it will be done by a geologist specializing in remote sensing looking at satellite imagery or aerial photos. A geologist specializing in basin analysis might chime in with information on the timing of the source rock and reservoir rock structure giving information on whether the source rock reached maturity before or after the potential traps were formed. A structural geologist might be consulted to advise on the potential for fractures in the area that might serve as migration pathways or potential porosity in the reservoir rock. Another geologist, a petrophysicist might examine the cores to determine the reservoir properties of the rock and correlate them to seismic properties. These would in turn give information to the geologist/geophysicist doing seismic interpretation of the area. Still another geologist specializing in well log analysis (also a potential petrophysicist) might correlate well logs from wells drilled in the general or regional area to determine the underlying sedimentary environment and facies distribution. He might consult a specialist in seismic stratigraphy or sedimentary petrology, both geologists for additional input. From this information a geologist would work up a volumetrics analysis to determine the potential recoverable oil present in the unproven reservoir. Another geologist might work up a risk analysis on the the potential reservoir to help determine if the prospect is worth drilling. Once the decision has been made, and drilling commences, a well site geologist would be responsible for monitoring the drillng progress and identifying potential hydrocarbon bearing zones from drill cuttings and mud returns. Another geologist would be responsible for mud logging. Once the well is complete, the well site geologist for the company drilling, would stipulate the zones to be logged by the service company. The service company logging engineer would recommend a log suite to be run. The company well site geologist would provide oversight and quality control on the log run and the data. A decision on whether to or how to complete the well and what intervals to perforate would be made. This data would be provided back to the geologists in the office to assess the results and if possible develop a reservoir model. If enough wells are present in the area a detailed reservoir model can be constructed from the logs and seismic data. If this is a wildcat or new field well the team might keep control or a reservoir or development geologist might be brought in to facilitate infill drilling to completely exploit the new found reservoir. The development or reservoir geologist might work closely with the reservoir engineer to plan out how to most efficiently exploit the reservoir. In some instances, like a small company, one geologist would fill nearly all the roles himself. In larger companies with more compartmentalization the roles might be carried out by separate individuals within the larger organization. I am sure I have overlooked something, but this will give you an idea of the many roles a geologist plays in finding petroleum.