普光地区深层碳酸盐岩气藏主控因素及有利区预测

Main Controlling Factors and Favorable Area Prediction of Deep Carbonate Gas Reservoirs in Puguang Area

普光地区深层海相地层是川东北地区重点勘探目标,现已发现普光、大湾等6个含油气区块,勘探前景较好,但随着多口探井连续失利,亟需加强对普光地区气藏特征及成藏条件的重新认识。为此,利用测井、地震、岩心描述、分析测试等资料对普光地区气藏类型及其主控因素进行分析。结果表明:研究区发育背斜类、背斜-岩性类、断层-岩性类3种气藏类型。气藏发育主要受4种因素控制,烃源岩有机质丰度高,生气强度大,生气范围广;镶边台地沉积环境下,储层主要发育生屑、鲕粒等白云岩,储集类型以孔隙型、孔隙-裂缝型、孔洞型为主,物性较好(平均孔隙度为8.20%,平均渗透率为79.50 mD);盖层岩性以膏盐岩为主,膏盐岩平均厚度在290 m以上,分布范围广;5条北东向大型断裂及多条北西向断裂构成普光地区油气运移的主要疏导体系。在此基础上,划分出4类成藏有利区,最有利区位于普光、毛坝、大湾区块。该研究可对普光地区深层碳酸盐岩油气下一步勘探开发提供理论指导和技术支持。

The deep marine strata in Puguang Area are the key targets for exploration in northeastern Sichuan.Six hydrocarbon-bearing blocks were discovered with good exploration prospects.such as Puguang and Dawan,With the successive failure of many prospecting wells,it is urgent to improve the re-recognition of characteristics and reservoir formation conditions of gas reservoirs in Puguang Area.Therefore,the types and main controlling factors of gas reservoirs in Puguang Area were analyzed according to logging data,seismic data,core description,analysis and testing data.The results showed that,there were three types of gas reservoirs in the study area:anticline,anticline-lithology,and fault-lithology.The development of gas reservoirs was mainly controlled by four factors.The source rock had high abundance of organic matters,high intensity of gas generation,and wide range of gas generation.In the sedimentary environment of rimmed platform,dolomite such as bioclast and oolite was developed in the reservoir.The dominate reservoir types were porous type,pore-fracture type and vuggy type,with sound physical properties(the average porosity was 8.20%and the average permeability was 79.50 mD).The lithology of the cap rock was mainly gypsum-salt rock,with an average thickness of more than 290 m and a wide distribution range.There were five large NE-trending faults and multiple NW-trending faults which constituted the main channel system for oil-gas migration in Puguang Area.On this basis,four types of favorable areas for accumulation were defined,with the most favorable zones located in Puguang,Maoba and Dawan blocks.The study can provide theoretical guidance and technical support for the further exploration and development of deep carbonate reservoirs in Puguang Area.