杏河-侯市-王窑地区长6油层组三角洲砂体成岩作用对油气聚集的影响

The Effect of Diagenesis of Sandbody on Hydrocarbon Accumulation in Chang 6 Reservoir of Yanchang Formation in Xinghe-Houshi-Wangyao Area of Ordos Basin

对鄂尔多斯盆地杏河-侯市-王窑地区三叠统延长组长6油藏的岩石学、成岩作用、储集物性变化规律、油藏类型及成藏机理等进行研究,结果表明:该区长6油藏类型主要为上倾岩性尖灭与次生成岩复合油藏;成岩作用是控制研究区油气聚集的关键因素。压实作用和胶结作用是破坏性的成岩作用,使得储层物性变差,压实作用和胶结作用分别造成砂岩中24.9%和12.0%的原生孔隙丧失,形成成岩遮挡;溶蚀作用是建设性成岩作用,溶蚀孔隙占总孔隙的20%～45%,形成次生孔隙带,控制了优质储层的发育。压实作用、胶结作用及溶蚀作用的相互作用,对油气的聚集产生了重要影响,这说明成岩作用可以作为相对独立的因素控制油藏圈闭。

The lithology,diagenesis,law of reservoir physical property changes,reservoir types and the oil accumulation mechanism of the Chang 6 Reservoir in Yanchang Formation of the Ordos Basin were analyzed and studied.The result indicates that the main reservoir types are composite reservoir assembled of the lithologic pinch-out pool and diagenesis traps,and diagenesis of Chang 6 Reservoir is the key point to control the oil accumulation.Study also shows that mechanical compaction and cementation are the main destructive diagenesis caused by the loss of porosity,which result in 24.9% and 12.0% porosity loss of the total porosity.Dissolution is positive and constructive diagenesis,it provides about 20%～45%secondary porosity of the total porosity,creates a secondary porous zone to the reservoir.As a result,the interaction of mechanical compaction,cementation and dissolution,has a major impact on the accumulation of oil.This shows that diagenesis can be used as a relatively independent factor in terms of control of reservoir traps.