Drilling exploration design controlled by pore pressure prediction from 2D seismic and well data: case study of South Sumatra Basin

Abstract

To have safe and economical in drilling design, an information of formation pore pressure is required. Pore pressure can be estimated from seismic data using a velocity to pore pressure transform. The objective of this paper is proposing the drilling exploration design for the case study of South Sumatra field, which is controlled by predicted pore pressure. The pore pressure is predicted by using Eaton method that used velocity from 2D seismic and was validated with well log data. The predicted pore pressure is used to design exploration drilling including casing depth and mud weight. Eaton parameter (N =1.1), shear stress (Ko= 0.6), Gardner (A = 0.198 and B = 0.268), which is used in this works, is gained from existing well data. The velocity model is derived from RMS velocity that should be converted into interval velocity. In addition, this velocity should be validated with the sonic log from existing well. The Normal Compaction Trend (NCT) from interval velocity that was combined with generated previous parameter is used for predicting pore pressure and fracturing pressure. Our experiment shows that based on pore pressure prediction, the drilling exploration design is divided into three sections. i.e. section 17-1/2”, 12-1/4” and 8-1/2” and four casing sections, i.e. Casing 20′, K-55, 90 ppf at 160 ft, casing 13-3/8′, K-55, 54.5 ppf at 1400 ft with mud weight 8.8 - 13.7 ppg, casing 9-5/8 ′, K-55, 40 ppf at 4000 ft with mud weight 9.5 - 14.0 ppg and casing 7′, L-80, 26 ppf at 5500 ft with mud weight 10.4 - 14.6 ppg.