New empirical equation to predict the pore pressure in oil reservoirs

• Published in: Arabian journal of geosciences Vol. 15; no. 8
• Main Authors: Allawi, Raed H., Al-Jawad, Mohammed S., Alfarge, Dheiaa
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-04-2022; Springer Nature B.V
• Subjects: Blowouts; Bulk density; Clay minerals; Compaction; Correlation; Data logging; Diagenesis; Drill string; Drilling; Earth and Environmental Science; Earth science; Earth Sciences; Empirical equations; Field tests; Fluids; Logging; Oil; Oil and gas fields; Oil field equipment; Oil fields; Oil reservoirs; Original Paper; Petroleum; Pore pressure; Pore water pressure; Pressure; Reservoirs; Sedimentary basins; Temperature effects; Iraq; Mud window: Drilling engineering; In situ stresses; Geomechanics; Oil wells; Pore pressure
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-022-09961-z

The deep sedimentary basins for petroleum accumulations are often under abnormal pressure due to different reasons. Such reasons include under-compaction, expansion of the reservoir fluids (oil, water, and gas), aqua-thermal effects, rock maturity, clay mineral diagenesis, and charging from other zones. Several drilling problems including blowouts and lost circulation can occur if the pore pressures are not correctly estimated prior to drilling operations. Therefore, having a specialized model or empirical equation to predict the pore pressure is necessary for economically vital and successful drilling operations in oil fields. This research proposed a new method for estimating the pore pressure in oil fields. The developed empirical equation was applied and validated in the most important major formations for the oil fields of southern Iraq, including Shiranish, Khasib, Mishrif, Ahmadi, Mauddud, Nahr Umr, Shuaiba, Zubair, Ratawi, and Yamama formations. This correlation was essentially built based on logging data including acoustic compressional wave, bulk density, and vertical depth obtained from onshore wells in G oilfield. The correlation model obtained from this research was validated by using the pore pressure measurements from modular formation dynamics tester (MDT) and drill stem test (DST). The new empirical equation provides a much easier way to handle normal compaction trendlines and gives accurate pore pressure estimations as compared with actual field tests. Moreover, this correlation is more accurate in its predicting capacity than other models like Eaton’s method and Bowers original method. More than 200 measurements for pore pressure in southern Iraq oil fields were used to validate this correlation and it has been found that this approach was so close to the real field measurements.