Reservoir Geology —A “New ” Role For The Explorationist
Authors: Pickel J.S. 
Published: March 2010

CANADA'S emergence as a producer of major oil occurred on February 13, 1947, just 36 years ago. A plaque commemorating that occasion can be viewed just a few miles south and east of the town of Devon, Alberta, a town which was created to service the Leduc - Woodbend area. Canada was still in a post-war recession, consequently, the promise of a new major industry spelled opportunity to a growing force of professionals, most world war II veterans, in both the earth sciences and in engineering.

The main body surrounding this key group were Canadian geology graduates trained mostly in hard rock geology. Many graduates had geological engineering degrees but few, if any, were absorbed into the engineering departments of the major companies. Instead, they became part of the exploration teams where their hard-won engineering training was all but forgotten.

On the other hand, engineering departments sought out mostly chemical and petroleum engineers, together with a smattering of mechanicals and engineering physicists for their future reservoir management teams, whose geological training was at best rudimentary.

It is not surprising, therefore, that the technical forces driving the industry were split into two diverse factions-explorationists on the one hand, production and engineering on the other, with little common language and very different goals.

Exploration philosophy has traditionally required a broad knowledge of sedimentation processes to develop geological trends favorable for accumulation of petroleum. When augmented with geophysics, source-rock analysis and a study of subsurface fluid systems, chances were good that sooner or later it would lead to a major discovery. Having made his mark, the explorationist was more than willing to relinquish control of follow-up drilling to the engineer, with little interest in the detailed geology of the reservoir.

The engineer has traditionally made his reputation in two ways; first by getting wells on production as cheaply and efficiently as possible, secondly by devising new schemes for enhanced recovery. These objectives are not always compatible.

In cutting front-end costs, false savings were often made, reducing the amount of coring, a basic geological tool. By the 1960s, more sophisticated petrophysical well logs were introduced, resulting in even more drastic reductions in core data. In some areas coring was cut out but not replaced by comprehensive logging programs. Also in the 1960s, the reservoir engineer was presented with a powerful new tool the digital computer for multi-dimensional, multi phase reservoir simulation. It was then possible to "model" the reservoir, match the production history. (If the reservoir was relatively simple), usually by adjusting the permeabilities. With a good model he could determine the most efficient plan for future reservoir management. Geological input to simulation models came much later, in the 1970s, when it was realized that no amount of number-crunching, (a.k.a. massaging of data), :could make certain models work, unless I they made geologic sense.

Meanwhile, where was the geological expertise necessary to fill this gap? Production geologists, working under engineers, had been utilized mostly for generating net pay and structure maps for volumetric estimates, usually with little or no regard to internal reservoir geometry.