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Characterization of in-situ stresses and its implications for production and reservoir stability in the depleted El Morgan hydrocarbon field, Gulf of Suez rift basin, Egypt
Journal of Structural Geology ( IF 2.6 ) Pub Date : 2021-05-04 , DOI: 10.1016/j.jsg.2021.104355
Ahmed E. Radwan , Souvik Sen

A comprehensive reservoir geomechanical analysis has been performed in the matured giant El Morgan field, Gulf of Suez to assess the effect of hydrocarbon production on stress magnitudes, reservoir stability, and fault slip potentiality. The average vertical stress (σv) gradient of the field is found to be around 22.93 MPa/km. Based on the rock properties and downhole measurements, virgin pore pressure (PP) and minimum horizontal stress (σhmin) gradients within the Middle Miocene Hammam Faraun and Kareem reservoirs are interpreted as 11.10–11.25 and 15.88–16.65 MPa/km, respectively. The latest measurements indicate 6–6.5 MPa pressure drop in the Hammam Faraun reservoirs, while Upper and Lower Kareem Formations are depleted by 8–9.5 and 10–11.75 MPa, respectively. The effect of depletion on σhmin is modeled using rock linear poroelastic approach. The Middle Miocene reservoirs exhibited average stress path values of 0.61–0.66, respectively. The study infers that the Kareem Formation has more chances of production-induced normal faulting at the present rate of depletion, as the reservoir stress path value is very close to its critical faulting limit. To maintain the production and minimize the bypassed oil, infill injector wells are commonly utilized in the El Morgan field. The reservoir stability threshold was evaluated by appraising critical pore pressure build up limits (PPc) during fluid injection at the present-day depletion level in various PP-stress coupling scenarios. A maximum pressurization window of 10 MPa and 8 MPa are interpreted in the Hammam Faraun and Kareem reservoirs (PPc of 23.33 MPa and 20.31 MPa) respectively, which are well below the fracturing limit of the overlying caprocks, thus ensuring seal integrity. This geomechanical study provided critical insights regarding the optimization of production and repressurization by the infill injector wells by minimizing the risk of subsurface instabilities.



中文翻译:

埃及苏伊士裂谷盆地贫化的El Morgan油气田的原地应力特征及其对生产和储层稳定性的影响

已经在苏伊士湾成熟的巨型El Morgan油田进行了全面的储层地质力学分析,以评估油气生产对应力大小,储层稳定性和断层滑动潜力的影响。磁场的平均垂直应力(σv)梯度约为22.93 MPa / km。根据岩石特性和井下测量,中新世哈马姆·法劳恩和卡里姆中层储层的原始孔隙压力(PP)和最小水平应力(σhmin)梯度分别被解释为11.10-11.25和15.88-16.65 MPa / km。最新的测量结果表明,哈曼法拉恩(Hammam Faraun)油藏的压降为6–6.5 MPa,而上和下卡里姆层分别减少了8–9.5和10–11.75 MPa。使用岩石线性多孔弹性方法模拟了耗尽对σhmin的影响。中新世中层储层的平均应力路径值分别为0.61-0.66。研究推断,在目前的枯竭率下,Kareem组有更多的机会由生产诱发的正断层,因为油藏应力路径值非常接近其临界断层极限。为了维持产量并最大程度地减少旁路油,El Morgan油田通常使用填充注入井。通过评估当前在各种PP应力耦合情况下的消耗水平下的流体注入过程中的临界孔隙压力建立极限(PPc)来评估储层稳定性阈值。Hammam Faraun和Kareem储层(PPc分别为23.33 MPa和20.31 MPa)解释了最大压力窗口为10 MPa和8 MPa,远低于上覆盖层的破裂极限,从而确保了密封的完整性。这项地质力学研究通过最大程度地降低了地下不稳定的风险,为充注井的生产和再加压的优化提供了重要的见识。

更新日期:2021-05-15
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