塔中Ⅰ号气田西部鹰山组碳酸盐岩储层类型划分及储层连续性分析

Classification and continuity analysis on carbonate reservoir of the Yingshan Formation in the western Tazhong I gasfield

非均质碳酸盐岩储层类型多样,成因机理复杂。不同成因、机理及尺度的孔、洞、缝常伴生发育,仅根据静态资料(野外露头、岩心、测井和地震等资料)难以划分储层类型。为此,以塔中Ⅰ号气田西部下奥陶统鹰山组层间岩溶缝洞型碳酸盐岩储层为例,以静态资料为辅、动态资料(酸压、试井和试采等资料)为主,将研究区储层划分为洞穴型、裂缝—孔洞型和孔洞型储层3种类型。结合地震正演和钻井资料,根据地球物理响应特征,将研究区储层地震反射特征划分为串珠状、片状和杂乱地震反射3种类型。串珠状地震反射储层中的小型洞穴、裂缝和孔洞均较发育,主要供液空间为裂缝—孔洞型储层,其次为洞穴型储层,片状和杂乱地震反射储层起主要供液作用的分别为裂缝—孔洞型和孔洞型储层。串珠状、片状和杂乱地震反射储层的发育程度具有较好的继承关系,部分杂乱地震反射储层受后期埋藏溶蚀作用的强烈改造形成串珠状和片状地震反射储层。此外,初步探讨了储层相对致密段的连续性及含油气特征,认为储层相对致密段的油气以吸附状态或游离状态赋存于孔隙和喉道中,且储层存在一定的横向连续性和连通性。

Types of the heterogeneous carbonate reservoir are various and its genetic mechanism is complex. The hole,cave and fissure with different genesis,formation mechanisms and scales always develop in company,thus it is difficult to classify reservoir types only using static data(outcrop,core,logging and seismic data,etc.). The carbonate interlayer karst reservoirs in the Lower Ordovician Yingshan Formation of the western Tazhong Ⅰ gasfield was chosen as an example,and the carbonate reservoirs in the study area were classified into three types:cavity,fracture-hole and hole mainly using dynamic data(acid fracture,well test,production test,etc.)with auxiliary of static data. Combining with seismic forward and well drilling data,the seismic reflection characteristics of the carbonate reservoir are divided into three types based on geophysical response characteristics:string beads reflection,flake reflection and messy reflection. Small caves,fractures and holes are more developed in the carbonate reservoirs with bead-like reflection,in which the fracture-hole reservoir is the main space providing liquid followed by the cave reservoir;fracture-hole and hole reservoir are the main space providing liquid with flake-like reflection and messy reflection respectively. The carbonate reservoirs with three kinds of seismic reflection developed with inheritance,the carbonate reservoirs with some messy reflections were reconstructed later strongly by burialdissolution to form carbonate reservoirs with bead-like and flake-like reflection. Besides,the oil and gas bearing characteristics of relatively tight reservoirs and its continuity were discussed preliminarily,and it is believed that the oil and gas in relative compacted segments accumulates in channels and throats in adsorbed or in free state,and the reservoirs are horizontally continuous and connected to some degree.