油气充注对成岩作用的影响

Effects of Hydrocarbon Emplacement to Diagenesis of Reservoirs

油气充注对成岩作用的影响有三个方面 :抑制石英和伊利石的胶结作用、油气中所有机酸对深部孔隙的溶蚀改造作用、油气超压对压实的缓冲作用。英国北海Miller油气藏等的资料显示 ,油气充注较早时 ,油区的石英胶结速率比水区的明显要低 ,石英的胶结丰度比一般预测值低 ,而孔隙度比一般的预测值要高。我国渤海湾盆地东营凹陷油田资料显示 ,无论浅部或深部 ,凡是含油砂岩 ,其长石类及碳酸盐类矿物的溶解都十分强烈 ,次生孔隙很发育 ,而不含油的砂岩 ,其矿物溶解及次生孔隙发育一般较差 ;油层的方解石、白云石含量一般比水层低 ,深层尤为明显。干酪根生成油气时的流体体积增加 ,可大大增加孔隙流体压力 ,产生超压 ,并可传递到储集层 ,因而大大增加对压实作用的抵抗能力。上述三方面实质上都为深部油气成藏改善了储层基础 ,对深部油气勘探具有非常现实的意义。

Diagenesis of reservoirs may be generally involved during hydrocarbon emplacement. The effects to diagenesis include the cementation that restrains quartz and illite, the reconstruction of porosity dissolved by organic acid in hydrocarbon, and the buffering to compaction yielded under superpressure during formation of hydrocarbon. Under these effects, the residual porosity in deep can be reconstructed and permeability can be improved, which provide well space for hydrocarbon accumulation in deep buried reservoirs. Some cases of typical reservoirs in Bohaiwan Basin and Turpan Basin are analyzed and compared with the Miller reservoir in United Kingdom (North Sea).