Post-Drill Pore Pressure and Fracture Gradient Analyses of Y-Field in the Offshore Tano Basin of Ghana

Abstract

A post-drill pore pressure and fracture gradient analyses were conducted on a field in the Tano Basin of Ghana with the primary objective of predicting as accurately as possible the pore pressure, fracture pressure and the overburden pressure from the well logs data of two wells. The wells were drilled offshore in water depths of about 95.4 m and 124.4 m. Eaton's method coupled with depth-dependent Normal Compaction Trendlines (NCT) and Mathews and Kelly method were used in determining the pore pressure and fracture gradient. The results indicate that average pore pressure gradient, fracture pressure gradient and overburden pressure gradient for the first well are 1.423 psi/m (8.34ppg), 3.514psi/m (20.6ppg) and 4.299psi/m (25.2ppg) respectively whiles values for the second well are 1.423psi/m (8.34ppg), 3.85psi/m (21ppg) and 4.299psi/m (25.2ppg) respectively. These values were predicted to be required to maintain the stability of the wells using accurate mud weight.