Pore Pressure Prediction Challenges in the Middle East Region

Abstract

Abstract In many hydrocarbons-prone provinces of the world (the North Sea, Gulf of Mexico, West Africa, Caspian and other areas) abnormal pore pressures have now been widely observed. Accurate assessment and prediction of pore pressure and fracture gradient formed an essential part of the planning process particularly for exploration and deep drilling where no or limited pressure data are available. Although the fundamental objective for pore pressure imaging is to provide pressure data ahead of drilling, the pore pressure analysis should be carried out at different stages of the drilling: (i) Pre-drill (using seismic and rock models), (ii) while drilling (act as support and update using real-time data) and finally (iii) post-drill (support role and improve pressure evaluation of an area). An estimation of pore pressure can be obtained from seismic velocities where disequilibrium compaction is the dominant pore pressure mechanism during all the three mentioned stages (pre-drill, while drilling and post-drill) by using a velocity-to-pore pressure transform. However, the borehole or/and surface seismic velocities must be the true estimation of the interval velocity of rocks as well as of adequate resolution particularly for well planning purposes. In case of presences of other pore pressure mechanism such as hydrocarbon generation, Osmosis, etc, the industry still does not have a established method(s) for pore pressure prediction and often such mechanism are ignored due to their complex nature and lack of predicative methods. Here, after reviewing the pore pressure challenges and mechanisms in the Middle East, we discuss the importance of the key pore pressure mechanisms such as; disequilibrium compaction, fluid migration, hydrocarbon generation.