深层—超深层碳酸盐岩储层形成机理新进展

深层—超深层碳酸盐岩领域是否存在规模有效储层长期存在争议。随着一批规模大、产量高的深层—超深层碳酸盐岩油气藏的发现,结束了是否存在有效储层的争议,但深层—超深层优质规模性储层的形成、保持机理又成为新的关注焦点。通过对普光气田上二叠统长兴组和下三叠统飞仙关组深层优质碳酸盐岩储层进行研究,提出了沉积—成岩环境控制早期孔隙发育、构造—压力耦合控制裂缝与溶蚀、流体—岩石相互作用控制深部溶蚀与孔隙保存的"三元控储"成因模式。随着勘探的推进和研究的深入,相继在塔里木盆地和四川盆地又发现了一些新类型储层。研究结果表明,四川盆地雷口坡组微生物岩储层与早期沉积组构密切相关,与鲕滩、生物礁等高能环境控制的储层有一定差异;塔里木盆地顺北地区存在多期活动的走滑断裂,在其影响下形成了断控洞穴、裂缝及沿缝溶蚀的断控储集体,与裂缝-孔隙型储层差别明显;塔里木盆地顺南4井发现了一套以缝洞和石英晶间孔为主要储集空间的热液硅化碳酸盐岩储层,其成因与大气淡水、有机酸、TSR等已发现的成岩流体溶蚀作用无明显关系。这些新类型储层的成因机理与"三元控储"成因模式的核心思想契合,但其现象与经典实例存在一定差异。这些新发现拓展了"三元控储"成因模式的内涵。

A new progress in formation mechanism of deep and ultra-deep carbonate reservoir

There has been a long-term dispute over whether effective large-scale reservoirs exist in the deep and ultra-deep carbonate fields. With the discovery of a series of large-scale and high-production deep and ultra-deep carbonate reservoirs, the dispute has ended. However, the formation and maintenance mechanism of deep and ultra-deep high-quality large-scale reservoirs has become a new focus. By studying the deep high-quality carbonate reservoirs of the Upper Permian Changxing Formation and the Lower Triassic Feixianguan Formation in the Puguang gas field, this paper proposes the genesis model of "three-element controlling reservoir", i.e., the development of early pores is controlled by sedimentary-diagenetic environments, fractures and dissolution are controlled by the structure-pressure coupling, and deep dissolution and pore preservation are controlled by the fluid-rock interaction. With the advancement of exploration and the deepening of research, some new types of reservoirs have been discovered in Tarim Basin and Sichuan Basin. The research results show that the microbolite reservoirs of Leikoupo Formation in Sichuan Basin are closely related to the early sedimentary structure, and have certain differences from the reservoirs controlled by high-energy environments such as oolitic beach and reef. There are multi-stage active strike-slip faults in the Shunbei area of Tarim Basin; under their influence, fault-controlling caves, fractures, and the fault-controlling reservoirs dissolved along fractures are formed, but distinctly different from the fracture-pore type reservoirs. A set of hydrothermal silicified carbonate reservoirs with fractures, caves and quartz intergranular pores as the main reservoir space was found in the Well Shunnan 4 in Tarim Basin, and their genesises has no obvious relationship with the dissolution of diagenetic fluids such as meteoric fresh water, organic acids and TSR. The genesis mechanisms of these new types of reservoirs are in line with the core idea of the genesis model of "three-element controlling reservoir", but the phenomena are somewhat different from classic examples. The connotation of the above genesis model has been expanded by these new findings.