Integrated Pore Pressure Prediction Approach for Successful Drilling in Tectonic Area

Abstract

Overpressure zone has been encountered in Tripura region based on previous drilling history and operators faced many complications in drilling Middle Bhuban. This article discusses successful drilling and logging of first vertical deep exploration well in extensive geological tectonics area where high pressure zones in the range of 2.0–2.10 SG at the depth of 3000m was expected. Surface seismic velocity and wireline logs were utilized to provide look-ahead pore pressure model using Monte-Carlo simulation. Deterministic models like Eaton, Bowers and Miller's Methods were used to validate the estimated Pore Pressure Profile. Above middle Bhuban, overcompaction is the key overpressure mechanism while, tectonic loading together with clay diagenesis plays key role for sudden change of pressure from 1.43SG to 1.85 SG within 200m. Mud weight in range of 1.85SG to 1.95 SG was used for successful drilling aided with real-time indicators like gas data and drilling parameters. Later on, actual formation pressure measurements were acquired, which matched closely with difference in range of 200psi only.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015