Pore pressure prediction : a case study of block A, Sabah Inboard & Baram Basin, Sabah Offshore

Abstract

Understanding pore pressure prediction is critical in various stage of frontier in petroleum process. Pore pressure related problems during drilling such as well control incidents, lost circulation & reservoir damages which often leads to expensive sidetracks, well abandonments, underground blowout & the loss of life of the drilling operators on the rig. Block A located in Sabah Basins, a few wells have been drilled & encountered unexpected overpressure which led to early abandonments & resulting to failure on achieving well objectives. The objective of this study is to first interpreted regional geology to understand the overpressure onset and overpressure mechanisms. Secondly, predict pore pressure using available nearby wells data within Block A, by using Eaton & Bowers methods and best fit method that has been optimized based on geological interpretation and model the pore pressure regionally. And finally estimates maximum possible hydrocarbon column length model for Block A remaining potential of deep gas overpressured play. The scope of this study will include geological study including sequence stratigraphy, seismic interpretation, seismic facies interpretation & analysis, gross depositional environment (GDE) & structural evolution of Block A. The pore pressure prediction using available well data and estimating maximum possible hydrocarbon column length for remaining potential of deep gas overpressured play. The regional geological studies result gave the estimated age of overpressure onset within Block A area. The pore pressure prediction results show that Eaton method has ability to better predict the overpressure regime compared to Bowers method. Using the Eaton method, an overpressure magnitude map has been produced, and using this overpressure magnitude map, 3 potential deep overpressure gas prospects maximum hydrocarbon column length has been estimated. Pore pressure model that has been built within this study, not only can be used to predict maximum hydrocarbon column length for current remaining potential of deep gas overpressured play, it is also can benefit future maximum hydrocarbon column length for any other potential play and it can be used for future drilling pore pressure prediction.