塔里木盆地奥陶系缝洞型碳酸盐岩岩溶储层成因及勘探启示

以岩心薄片、实验分析数据、钻录井、测井、地震等资料为基础，按照储层成因机理对塔里木盆地奥陶系碳酸盐岩岩溶储层进行了分类，并对各类储层的分布、储集空间类型及主控因素进行了系统分析。研究结果表明：(1)塔里木盆地奥陶系缝洞型岩溶储层按成因可划分为5类，分别为（准）同生岩溶储层、层间岩溶储层、顺层岩溶储层、潜山（风化壳）岩溶储层和受断裂控制岩溶储层。(2)（准）同生岩溶储层分布于台缘或台内礁滩相，有效储层在台缘连片发育，在台内零星分布，由颗粒灰岩因海平面下降而短期暴露淋溶形成，基质孔和溶缝、溶洞均发育，通常叠加后期层间岩溶作用或潜山岩溶作用，从而形成复合型岩溶储层。(3)层间岩溶储层发育于内幕区，与碳酸盐岩层系内部中短期的平行或微角度不整合面相关，呈准层状分布，储集空间以洞穴型为主，裂缝-孔洞型和孔洞型次之。(4)顺层岩溶储层与潜山周缘的斜坡背景、先存孔隙和裂缝有关，环潜山周缘呈环带状分布，以洞穴型和裂缝-孔洞型为主，90%以上的溶蚀孔洞及洞穴通过断裂及裂缝相连通。(5)潜山（风化壳）岩溶储层发育于潜山区，与中长期的角度不整合面相关，受断裂和裂缝影响大，准层状分布，峰丘地貌特征明显，根据围岩...

Genesis and exploration enlightenment of Ordovician fracture-vuggy carbonate karst reservoirs in Tarim Basin

Based on core thin section, experimental analysis, drilling, logging and seismic data, the Ordovician carbonate karst reservoirs in Tarim Basin were classified according to the reservoir genetic mechanism, and the distribution, space types and main control factors of various reservoirs were analyzed. The results show that:(1) The Ordovician fracture-vuggy karst reservoirs in Tarim Basin can be divided into five types according to their genesis:(quasi-) syngenetic karst reservoirs, interlayer karst reservoirs, bedding karst reservoirs, buried hill(weathering crust) karst reservoirs and fault-controlled karst reservoirs.(2) (Quasi-) syngenetic karst reservoirs, also known as reef-shoal karst reservoirs, are the reservoir formed by short-term(transient) exposure and leaching of reefshoal facies granular limestone at the platform edge or within the platform due to sea level drop, with matrix pores, dissolved fractures and dissolved caves being developed. They are usually superimposed with later interlayer karst or buried hill karst to form complex karst reservoirs.(3) The interlayer karst reservoirs are developed in the inner zone, and they are related to the parallel(micro-angle) unconformity surface in the carbonate strata and distributed quasi-stratified. The reservoir space is mainly cave type, followed by fracture-vuggy type and vuggy type.(4) The bedding karst reservoirs are related to the slope background, pre-existing pores and fractures around the buried hill, and the surrounding of the buried hill is distributed in a ring band, dominated by vuggy type and fracture-vuggy type, and more than 90% of the dissolved pores and caves are connected through faults and fractures.(5) The buried hill(weathering crust) karst reservoirs are developed in buried hill area. They are related to medium to long-term angle unconformity and greatly affected by faults and fractures. They are quasi-stratified and have obvious characteristics of peak and hill geomorphology. According to the lithology of the surrounding rocks, they can be divided into limestone buried hill karst reservoirs and dolomite weathering crust karst reservoirs. The limestone fracture-vuggy system is developed, the matrix pores are not developed, and the dolomite fracture-vuggy is underdeveloped, mainly consisting of dolomite intercrystalline dissolved pores and fractures.(6) Controlled by faults, karst reservoirs are mainly developed in the fault development area of inner zone. The fractures and vuggy are developed with large burial depth, large scale and long span, and they are distributed in a grid-shape along the faults, dominated by fracture-vuggy type, followed by fault-cave type. The more developed the faults and fractures are, the more developed the dissolved vuggy and caves are, and the higher and more stable the single well oil testing productivity is.(7) Karst reservoirs in the study area are largely developed in the interior area, mainly bedding karst reservoirs and karst reservoirs controlled by faults, with great exploration potential.