川西坳陷J_2s储集岩特征与孔隙形成、保存机制

①通过对川西坳陷中段新场气田及其它地区中深层上沙溪庙组 (J2 s)气层储集空间类型的研究 ,提出了原生孔隙是中深层重要的一种储集空间类型 ;②将岩石学、储层有机地球化学的分析与川西坳陷油气演化历史、构造发展史相结合 ,论述了次生溶孔形成的化学机理、发生时期和原生残留粒间孔隙的保存机制 ;③明确指出原生孔隙是燕山期烃类发生运移聚集的证据 ,油气具早期富集特征 ,而次生溶孔是燕山中晚期以来与运移、致密、超压同步形成的产物 ;④根据成岩改造的次生溶孔与残留原生孔隙在构造上分布的极不均一性和钻探实际资料 ,确认复合圈闭是中深层气藏的主要圈闭类型 ;⑤根据中深层储集岩特征与成藏史相结合进行的综合分析 ,提出川西坳陷中深层领域的勘探方向应该是燕山期古构造带上形成的复合圈闭

CHARACTERISTICS OF J 2 s RESERVOIR ROCKS IN WEST SICHUAN DEPRESSION AND THEIR PORE FORMATION AND PRESERVATION MECHANISMS

Through a research on the types of storage rooms in the medium deep Upper Shaximiao Formation(J 2 s )gas reservoirs in Xinchang gas field in the middle section of West Sichuan Depression and in the other places,it is proposed that the primary pores are the important type of storage rooms in the medium deep reservoirs.The chemical mechanism of forming secondary solution pores,their generation time and the preservation mechanism of primary residual intergranular pores are espounded by combining the analyses of petrology and reservoir organic geochemistry with the hydrocarbon evolution history and structural history of West Sichuan Depression.It is definitely pointed out that the primary pores are the evidence of hydrocarbon migration and accumulation in Yanshanian and the oil and gas are of the property of early enrichment;and that the secondary solution pores have been the product of synchronistical formation of gas entrance,compaction and overpressure since Middle Late Yanshanian.In light of the non homogeneity of distribution of the diagenetically reformed secondary solution pores and residual primary pores over the structure and the drilling data,it is determined that the combination trap is the principal trap of the medium deep gas reservoirs.On the basis of a comprehensive analysis of combining the characteristics of the medium deep reservoir rocks with the reservoir formation history,it is proposed that the targets of prospecting the medium deep gas reservoirs should be the combination traps formed on the Yanshanian palaeostructural belt.