Abstract: Geological Imagination - 1982

By

John M. Parker

Geological imagination is alive and well in 1982. The current slow-down in leasing, seismic work and wildcat drilling is causing companies and independents to be more selective in their spending, which means being more scientific. We are doing better work in frontier areas where we now have the seismic technology to do the job but in the past have lacked the necessary geological background and imagination.

Seismic data on cross sections must be interpreted from the basement up to the grass roots. You must think about each depositional sequence, compaction, each period of folding, faulting, intrusion, salt solution and collapse, and erosion. Only if you make a complete analysis of the total sedimentary section and relate that analysis to the vagaries of sound waves, velocities, geometry of folds and faults, migration problems, surface velocity problems, etc. will you be an "oil finder".

Better seismic data are the key in three current plays: 1. very deep, 20,000 feet, South Louisiana, Miocene; 2. very deep, 22,000 feet in South Texas, Lower Cretaceous, Sligo; 3. very shallow, 1600 feet, eastern Colorado, Upper Cretaceous Niobrara chalk. Someone with imagination had to ask for and obtain these better seismic data. Someone with imagination and an excellent background in the geology of the area had to interpret the seismic cross sections. Someone who knows how rocks fold and fault, based on surface mapping experience and subsurface mapping experience, must contour the structure from the seismic data. Since control is never infinite, and may be of poor quality, imagination is critical for the person doing the contouring.

Interpretation and reinterpretation of structure and stratigraphic sequences in the three plays mentioned above will provide many billions of cubic feet of gas if the proper drill sites are picked. Some of these plays may not be drilled until we have had two or three cold winters and until we have a firmer outlook on gas demand and price.

Imagination is of no value in our business unless it is used with a great deal of geological knowledge. That is why we have the AAPG Bulletin, technical meetings, field trips and field geology courses, and continuing education schools.

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