A modified approach to predict pore pressure using the D exponent method: An example from the carbonera formation, Colombia

Abstract

The methodology for pore pressure prediction known as D exponent is a function of an exponent of adjustment that was originally defined for the Gulf of Mexico (Jorden & Shirley, 1966; Eaton, 1972). A limiting factor of this methodology is the definition of the Normal Compaction Trend (NCT), which needs to be interpreted from the data (Mouchet & Mitchell, 1989). In this study, the D exponent methodology was modified to make it applicable to the Oligocene Carbonera Formation in an oil field of the Llanos foot-hills, Colombia. The approach consisted of calculating the ratio between effective stress and the D exponent at each well, in order to find a robust NCT for the entire field, thus reducing subjectivity in the traditional D exponent methodology. Pore pressure determinations from Measured Direct Tests (MDT) at one well confirm the predictive capability of our approach.