邻水–大竹地区长兴组生物礁储层特征及发育模式

Characteristics and Development Model of Changxing Formation Bioreef Reservoir in Linshui-Dazhu Area

摘要: 为了进一步弄清邻水–大竹地区长兴组生物礁储层的非均质性，基于岩心、岩石薄片、物性测试及地震资料，开展了长兴组生物礁储层特征及发育模式研究。结果表明：长兴组生物礁的空间展布受沉积古地貌控制较为明显，发育有台地斜坡生物礁、台地边缘生物礁和台内洼陷生物礁3种类型，在长兴组二段及长兴组三段的生物礁相对更加发育。生物礁灰岩在后续的构造成岩过程中形成了颗粒白云岩、晶粒白云岩、颗粒灰岩、晶粒灰岩等岩性。其中，白云岩、颗粒灰岩及生物礁灰岩是主要的储集岩类。发育的储集空间有孔隙、溶洞及裂缝等类型，但裂缝–孔隙型为主要的储集类型。储层物性较差，总体表现为低孔低渗和低孔超低渗储层。生物礁储层的发育程度受沉积作用、成岩作用及构造作用的共同控制。长兴组一段沉积时期主要发生同生–准同生白云化作用和各种溶蚀作用，长兴组二段沉积期除发生少许断裂作用外，主要发生了各种溶蚀作用和埋藏白云化作用。在长兴组中后期，各种构造作用及峨眉山省火山作用形成的各种断裂及热液活动促进了各类溶蚀作用的发生及热液白云岩的形成。

Abstract: In order to further clarify the heterogeneity of the Changxing Formation reef reservoir in the Linshui Dazhu area, a study was conducted on the characteristics and development patterns of the Changxing Formation reef reservoir based on core samples, rock thin sections, physical property testing, and seismic data. The results indicate that the spatial distribution of biological reefs in the Changxing Formation is significantly controlled by ancient landforms and stratigraphy. There are three types of biological reefs developed: platform slope biological reefs, platform edge biological reefs, and platform depression biological reefs. The biological reefs in the second and third members of the Changxing Formation are relatively more developed. During the subsequent tectonic process, biogenic reef limestone forms various lithologies such as granular dolomite, grain dolomite, granular limestone, and grain limestone. Among them, dolomite, granular limestone, and biogenic reef limestone are the main reservoir rock types. The developed reservoir space includes types such as pores, caves, and fractures, but the reservoir type is mainly fracture pore type. The reservoir has poor physical properties and is generally characterized by low porosity, low permeability, and low porosity, ultra-low permeability reservoirs. The development degree of reef reservoirs is jointly controlled by sedimentation, diagenesis, and tectonic processes. The first sedimentary period of the Changxing Formation mainly experienced syngenetic quasi syngenetic dolomitization and various dissolution processes, while the second sedimentary period of the Changxing Formation mainly experienced various dissolution and burial dolomitization processes, except for a small amount of faulting. In the middle and late stages of the Changxing Formation, various tectonic processes and volcanic activity in Emeishan Province during the late Changxing Formation promoted the occurrence of various dissolution processes and the formation of hydrothermal dolomite.