基于古应力场模拟的多期区域构造裂缝分布预测评价技术—以中国泌阳凹陷安棚油田为例*

天然裂缝是地层中常见的地质构造现象,系统研究目标区储集层裂缝的分布及发育规律,这对于提高井区产能和调整开发方案具有重要的理论和实际意义。以安棚油田深层系为例,介绍基于古应力场模拟的多期次区域构造裂缝分布预测技术。根据各类岩心资料对裂缝的组系特征、力学性质进行解释和评价,结合研究区构造演化特征,进行岩石破裂力学机理分析,明确了研究区裂缝成因类型主要为区域构造裂缝,为本次裂缝的分布预测技术奠定了基础。结合野外岩心裂缝特征、裂缝充填物次生方解石稳定同位素测定及储层岩石声发射实验结果,确定储层岩石的破裂期次。参考研究区的地质、构造、沉积相展布资料,以岩石力学和构造力学理论为基础,对研究区建立地质模型、力学模型,并分期次进行古应力场模拟研究。结合摩尔-库伦岩石强度理论,通过裂缝发育指数和岩石受力破裂程度多元拟合对研究区裂缝进行预测及评价。

The regional tectonic fracture distribution prediction technique of different generations based on the palaeostress field simulation- A case study from Anpeng oil-field

Natural fracture is a geological structure phenomenon that is widely distributed in strata. Conducting a systematic study on the distribution and development laws of the fracture in reservoir of the target areas is of theoretical and practical significance for improving the borefild productivity and adjusting the development program. Focusing on the deep sequences of Anpeng Oilfield, the paper introduces the regional tectonic fracture distribution prediction technique of different generations based on the palaeostress field simulation. The paper explains and evaluates the system characteristics and mechanics property of fracture according to the data of various rock cores. Combining with the tectonic evolution characteristics of the study areas, the paper makes an analysis to the mechanics mechanism of rock failure and makes it clear that the type of the cause of fracture in the study areas is mainly regional tectonic fractures, which has laid a foundation for the prediction technique of the fracture distribution. The paper determines the generations of the reservoir rock failure on the basis of the field rock cores characteristics, the secondary calcite stable isotope measurement of the fillings in fracture and the acoustic emission tests of the reservoir rocks. Referring to the geology, tectonics and sedimentary facies, the paper establishes the geologic model and mechanical model at the study areas based on the theory of rock mechanics and structural mechanics, and conducts the palaeostress field simulation research by generations. Combining with Mohr-Coulomb Rock Strength Theory, the paper predicts and evaluates the fracture according to fitting curve of fracture development index and rock failure coefficient. The evaluation and the actual fracture information on the work site have very good consistency, so we can get a conclusion that this technique is practical.