摘要
江汉盆地新沟嘴组页岩油地质评价资源量为3.6×108 t,具有良好的勘探潜力,其中地质评价Ⅰ类有利区陈沱口凹陷有多口井在新沟嘴组新下段Ⅱ油组泥质白云岩中获得油流。由于页岩油井通常采用“水平井+分段压裂”工艺实现经济开采,因而地应力研究对该区水平井储层压裂改造具有重要的意义。三维地应力建模研究的核心问题在于提升井间地应力预测效果,传统的有限元方法由于方法本身的限制,井间预测效果较差,有必要利用地震资料反演技术来提升井间地应力预测的效果。针对该区页岩层矿物组分多、局部发育硫酸盐岩、地应力条件复杂的问题,首先对新沟嘴组页岩层开展基于实验室测量值约束的精细测井评价,其结果与岩心全岩X衍射测量结果吻合;在此基础上,选择自相容近似地震岩石物理建模流程,对目标层的弹性参数进行了正演模拟,正演结果与实测曲线基本吻合。然后,基于地层压力、实验室测量的岩石力学性能参数和测井解释结果,依据不同岩性的动静态关系,采用有效应力比值和构造应变法计算井的地应力参数。最后运用基于地震叠前反演技术的三维地应力建模方法,使用与一维地质力学建模相同的相关性和参数约束,建立了新沟嘴组页岩油的三维地应力模型。与一维地质力学研究成果相比,该三维地应力模型提取的伪曲线与工区大部分井一维地应力结果基本吻合,验证了该方法在新沟嘴页岩油地应力评价中的适用性和准确性。
Shale oil resources for exploration in the Xingouzui Formation,the Jianghan Basin were geologically assessed to be 3.6×108 t,and oil flow was obtained at several well sites from argillaceous dolomites in the lower Xingouzui Formation,the Chentuokou sag which was evaluated to be Grade-I promising prospect.Economic shale oil production is usually achieved using horizontal well drilling+staged fracturing;thus stress information is important to fracturing stimulation of horizontal wells.A crucial issue in 3D stress modeling is how to improve cross-well prediction.The finite element method routinely used cannot yield good results due to its own limitations;thus our efforts focus on seismic inversion to improve cross-well prediction.In view of the problems related to multi-mineral,local sulfate rocks,and complicated stress conditions in the area of interest,log data-based evaluation is performed under the constraints of lab data for Xingouzui shale beds,and the results are validated using core measurements of X-ray diffraction.Rock physical modeling is achieved using self-consistent approximation to calculate elastic parameters of shale beds;modeled results agree with measured curves.Based on formation pressure,rock mechanical properties measured in the lab,logging interpretation,and dynamic-static relations of different lithologies,effective stress ratio and tectonic strain methods are employed to calculate in-situ stress parameters at well sites.The final 3D stress model of Xingouzui shale beds is established using prestack seismic inversion results and the correlation and parameter constraints equal to those used in 1D geomechanical modeling.By comparison,pseudo-curves extracted from the 3D model are basically consistent with 1D modeled results at most well sites in the area,which demonstrates the feasibility and credibility of this method in stress evaluation for Xingouzui shale beds.
作者
钟庆良
石秀平
孙树林
ZHONG Qingliang;SHI Xiuping;SUN Shulin(Geophysical Research Institute of Sinopec Jianghan Oilfield Company,Wuhan 430073,China;GeoSoftware Technology Services(Beijing)Co.,Ltd.,Beijing 100016,China)
出处
《石油物探》
CSCD
北大核心
2024年第2期472-486,共15页
Geophysical Prospecting For Petroleum
基金
国家科技重大专项(2017ZX05049-005-002)资助。
