Exploration in Braided Stream Environments Using Dipmeter Analysis

L. M. Grace, W. C. Stephens, Jr.

Longitudinal bars deposited in braided streams form some of the more prolific hydrocarbon traps in fluvial sequences. Exploration and development of these systems are challenging despite the simple sand geometry involved. The productive longitudinal bars are usually nearly straight but extremely narrow. Recognizing this environment and differentiating it from fluvial meander channels are difficult but critical tasks. Several normal rules of dipmeter interpretation are modified to accommodate this system. Blue patterns can be the result of current bedding, lateral accretion, or downstream accretion. Since the sand geometry may be perpendicular or parallel to the geologic feature, an accurate evaluation of the event is particularly important.

After a braided-stream trend is determined in an area, offset exploration wells can be projected with high confidence in areas of little or no well control.

This technique has been successfully applied to Permian and Pennsylvanian sections in several fields in west-central Texas.

AAPG Search and Discovery Article #91037©1987 AAPG Southwest Section, Dallas, Texas, March 22-24, 1987.