Seismic pressure-prediction method solves problem common in deepwater Gulf of Mexico

Abstract

A novel method of predicting pore pressure gradients from seismic velocities has overcome a problem common in the deepwater Gulf of Mexico. The method, based on a model of geopressures that uses available formation temperature measurements, does not require the normal shale compaction trend. This is crucial in deep water, where geopressures often start shallow below mud line and make establishing the normal trend difficult. Pore pressure prediction methods that use the shelf`s depositional model are not accurate enough for the deep water. The shelf model consists of a significantly thick, hydrostatically pressured section, which is used to establish the normal pressure interval travel time (ITT)-shale compaction trend as a reference. This article describes the method, discusses preparation of the velocity data, and shows results from one shelf and three deepwater wells in which the method is successful.