Pore pressure prediction in shales undergoing compaction, including both mechanical and chemical processes, is typically related to the mechanism referred to disequilibrium compaction. However, even when this mechanism is established and the normal compaction trend in wireline data, as a proxy for shale porosity, is well constrained, the pore pressure prediction may be in error because of the lithological variation in shale composition.  

There are several factors that affect the magnitude of the log response within a shale beyond compaction-related porosity reduction (e.g., cementation, different fractions of non-clay material, variation in clay content, different fluids in the pore space, and the presence of organic matter). From one well to the next, and from one formation to another, rock property variations are common and must be accounted for with rock physics models to reduce uncertainty.

In this presentation, a series of rock physics models will be used on a case study well from the UKCS to correct the measured wireline data to reduce uncertainty and improve both the accuracy and the confidence in the final pore pressure solution.