基于阵列声波测井估算碳酸盐岩储层岩石力学和地应力参数OA北大核心CSTPCD
Estimation of the rock mechanics and in-situ stress parameters of carbonate reservoirs using array sonic logging:A case study of Shunbei No.4 block
地质力学分析在油气藏勘探开发过程中发挥着重要作用,顺北油气田中—下奥陶统一间房组—鹰山组储层地应力研究相对滞后.对比分析了顺北 4号带下古生界中—下奥陶统一间房组—鹰山组碳酸盐岩不同类型储层的岩石力学和地应力特征,同时探讨了微观颗粒结构对碳酸盐岩储层地应力和岩石力学参数的控制作用,为顺北地区超深层碳酸盐岩储层评价提供了基础地质依据.基于弹簧组合模型,通过岩石力学实验和阵列声波测井确定了岩石力学和地应力特征,通过铸体薄片和X射线CT扫描表征碳酸盐岩的微观孔隙结构.研究结果表明:顺北 4号带一间房组—鹰山组杨氏模量分布在 50～89 GPa,抗压强度在 99～136 MPa,泊松比在 0.25～0.32;地层最大水平主应力为 200～225 MPa,最小水平主应力为125～160 MPa.一间房组—鹰山组碳酸盐岩不同类型储层的岩石力学参数和地应力存在明显差异,从Ⅰ类、Ⅱ类、Ⅲ类到非储层段碳酸盐岩的杨氏模量、抗压强度和最大水平主应力明显增大,而泊松比和最小水平主应力变化不大.相比于一间房组—鹰山组泥晶灰岩,砂屑-生屑灰岩方解石颗粒较大,颗粒黏结程度降低,导致岩石抗压强度和杨氏模量减小;砂屑-生屑灰岩部分方解石颗粒呈次圆状或圆状,颗粒三维空间球度较大,颗粒之间咬合作用减弱,使得岩石的抗压强度和杨氏模量减小;砂屑-生屑灰岩存在大量的孔隙和裂缝,灰岩易沿着潜在的微裂缝面或者颗粒接触面摩擦滑动甚至破裂,同样导致岩石抗压强度和杨氏模量减小.此外,一间房组—鹰山组泥晶灰岩受热液作用影响,部分白云石交代为石英,导致泥晶灰岩的抗压强度和杨氏模量增加.岩石的宏观力学特征和岩石力学参数受岩石微观颗粒结构的制约,一间房组—鹰山组杨氏模量、抗压强度和最大水平主应力低值区即为顺北 4号带优势储层发育区带.
[Objective]Geomechanical analysis plays a crucial role in exploring and developing oil and gas reservoirs.However,the study of in-situ stress in the Yijianfang-Yingshan formations of the Middle to Lower Ordovician in the Shunbei oilfield has lagged behind.This paper compares and analyzes the rock mechanics and in-situ stress characteristics of different types of carbonate reservoirs in the Yijianfang-Yingshan formations of the Lower Paleozoic Ordovician in the Shunbei No.4 block,and explores the control effect of micro-grain structures on the in-situ stress and rock mechanics parameters of carbonate reservoirs.It aims to provide fundamental geological data for the evaluating of ultra-deep carbonate reservoirs in the Shunbei area.[Methods]This study,based on the spring combination model,determined the rock mechanics and in-situ stress characteristics through rock mechanics experiments and array acoustic logging,and characterized the micro-pore structure of the limestone using casting thin sections and X-ray μ-computed tomography analysis.[Results]The results indicate that the Young's modulus of the Yijianfang-Yingshan formations ranges from 50 to 89 GPa,the compressive strength from 99 to 136 MPa,and the Poisson's ratio from 0.25 to 0.32.The maximum horizontal principal stress of the formations ranges from 200 to 225 MPa,while the minimum horizontal principal stress ranges from 125 to 160 MPa.[Conclusion]Significant differences in rock mechanics parameters and in-situ stress exist among different types of carbonate reservoirs in the Yijianfang-Yingshan formations.From Type Ⅰ to Type Ⅲ and non-reservoir carbonate rocks,the Young's modulus,compressive strength,and maximum horizontal principal stress increase dramatically,while the Poisson's ratio and minimum horizontal principal stress show little change.Compared to micritic limestone,sandy-bioclastic limestone has larger calcite particles and reduced particle cohesion,resulting in decreased compressive strength and Young's modulus.Some calcite particles appear sub-rounded or rounded with higher three-dimensional particle sphericity,also leading to weaker intergranular engagement and further reduction in compressive strength and Young's modulus.The presence of numerous pores and fractures in sandy-bioclastic limestone facilitates frictional sliding and potential failure along microfractures or particle interfaces,contributing to lower compressive strength and Young's modulus as well.In addition,micritic limestones in the Yijianfang-Yingshan formations are affected by hydrothermal activity,with some dolomite being replaced by quartz,which increases the compressive strength and Young's modulus.The macroscopic mechanical characteristics and rock mechanics parameters of the rock are constrained by the micro-grain structures.The low-value zones of the Young's modulus,compressive strength,and maximum horizontal principal stress in the Yijianfang-Yingshan formations are identified as the advantageous reservoir development zones in the Shunbei No.4 block.
刘军;黄超;周磊;陈群;张生龙
中国石化西北油田分公司勘探开发研究院,新疆乌鲁木齐 830011中国地质科学院地质力学研究所,北京 100081
地质学
顺北4号带碳酸盐岩岩石力学参数地应力
Shunbei No.4 blockcarbonate rockrock mechanic parametersin-situ stress
《地质力学学报》 2024 (003)
394-407 / 14
中国博士后科学基金项目(2018M631541);中国地质调查局地质调查项目(DD20221660-1,DD20242777)This research is financially supported by the Chinese Postdoctoral Science Research Fund(Grant No.2018M631541)and the Geological Survey Projects of the China Geological Survey(Grants No.DD20221660-1 and DD20242777).
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