成岩作用与油气侵位对鄂尔多斯盆地延长组砂岩储层物性的影响  

Impact of Diagenesis and Hydrocarbon Emplacement on Sandstone Reservoir Quality of the Yanchang Formation (Upper Triassic) in the Ordos Basin

作　　者：罗静兰[1] 刘小洪[1] 林潼[1] 张三[1] 李博[1] 

机构地区：[1]西北大学大陆动力学教育部重点实验室,西北大学地质学系西安710069

出　　处：《地质学报》2006年第5期664-673,共10页Acta Geologica Sinica

基　　金：国家重点基础研究发展计划"973"项目(编号2003CB214603);长江学者和创新团队发展计划(编号IRT0559)资助的成果

摘　　要：对鄂尔多斯盆地不同地区上三叠统延长组砂岩的岩石学、储层物性与成岩作用特征及其分布与变化规律的对比研究表明,盆地东部与盆地西部延长组来自不同物源区。压实作用是造成延长组砂岩孔隙丧失的主要原因,分别使长1—长3砂岩和长4+5—长10砂岩丧失的平均孔隙度占原始孔隙的59%和73.3%。胶结作用导致长1—长3和长4+5—长10砂岩丧失的平均孔隙度分别占原始孔隙的25.8%和27.5%,碳酸盐是造成砂岩物性降低的主要胶结物。晚成岩阶段盆地中发生的油气侵位和烃类物质在砂岩孔隙中的聚集抑制了自生石英和碳酸盐胶结物的沉淀。油气的富集对伊利石和绿泥石薄膜的形成没有明显的影响,后者可能对油气的聚集起了促进作用。晚成岩阶段水-岩反应产生的无机酸性流体和烃源岩中有机质向烃类转化过程中产生的有机酸性流体、以及表生成岩阶段的大气降水是导致砂岩储层物性改善的重要途径。Research on sandstone rock types, detrital minerals and cements, textures, porosity types and measured porosity and permeability of the Yanchang Formation in the Ordos Basin implies that provenances of the Yanchang Formation in the eastern part and the western part of the basin came from different source rocks. Study also shows that mechanical compaction is the main factor caused the loss of porosity, which resulted in 59% and 73. 3% porosity loss of the total porosity for the Chang 1-Chang 3 fluvial sandstones and the Chang 4＋ 5-Chang 10 deltaic-lacustrine sandstones, respectively. The porosity loss caused by cementation is 25.8 and 27. 5% of the total porosity for the Chang 1-Chang 3 sandstones and the Chang 4-q-5-Chang 10 sandstones, respectively. In the cements, carbonate is the major cement that reduced the reservoir quality of the sandstones. Hydrocarbon emplacement occurred during the late diagenetic phase prevented part of authigenic quarts and carbonate cement precipitation, however, it had unobvious effect on the formation of chlorite coatings and illite cement, and the later in turn promoted hydrocarbon accumulation. Inorganic acidic fluids resulted from reactions between rock-water and organic acidic liquids produced by transformation processes from organic matters into hydrocarbons in the source rocks, and penetrated meteoric water in the Yanchang Formation during the epidiagenetic phase caused dissolution of the detrital minerals and the readily soluble cements Such as carbonate, which resulted in lots of dissolution pores and thus contributed retention of reservoir quality for the sandstones.

关 键 词：岩石学 成岩作用与油气侵位 储层物性 延长组 鄂尔多斯盆地 

分 类 号：P618.130.2[天文地球—矿床学] P588.121[天文地球—地质学]