川西彭州地区雷口坡组碳酸盐岩储层裂缝特征及主控因素

摘要

Several types of natural fractures occur in the reservoir of the Leikoupo Formation in Pengzhou area,western Si-chuan Basin,and their major controlling factors are very complex.Geological,geophysical and experimental data are inte-grated to study the genetic types and characteristics of these fractures,and analyze the geologic factors controlling the forma-tion of tectonic factures.In the reservoir of the Leikoupo Formation,the predominant fracture type is tectonic facture,fol-lowed by diagenetic fracture.The tectonic factures can be classified into three types:high angle fractures,oblique fractures and low angle fractures.Each type of fracture has its own specific dominant orientation,indicating that they are resulted from multiple stages of tectonic movement.The fractures are effective in general.High angle fractures are all effective,while some low angle fractures and oblique fractures are ineffective.Fractures are highly developed in dolomite,but are poorly de-veloped in limestone.Due to the impacts of differences of fracture genetic mechanisms and the timing of fracture formation and reservoir diagenetic evolution,the development of high angle fractures and oblique fractures are mainly controlled by faults and their disturbed stress field,thickness of rock mechanics layer and physical properties of reservoirs,while that of the low angle fractures are mainly controlled by occurrences of local strata and structures and sedimentation.%川西彭州地区雷口坡组碳酸盐岩储层中发育多类天然裂缝且主控因素复杂.利用地质、地球物理及分析测试等资料,阐明了天然裂缝的成因类型及发育特征,并对控制不同类型构造裂缝发育的各地质因素进行了分析.彭州地区雷口坡组储层主要发育构造裂缝,其次为成岩裂缝;构造裂缝可分为高角度缝、斜交缝和低角度缝,各类裂缝具有各不相同的优势产状,表明在多期构造运动下形成.裂缝总体有效性较好,其中高角度缝均为有效缝,无效缝主要分布在低角度缝和斜交缝中.裂缝在白云岩类中最为发育,而在灰岩类中发育程度相对较弱.由于受裂缝成因机制差异性及裂缝形成期次与储层成岩演化阶段匹配关系的影响,高角度缝及斜交缝的发育主要受断层及其扰动应力场、岩石力学层厚度及储层物性控制,而低角度缝的发育主要受局部构造地层产状及沉积因素控制.