川东北地区须家河组天然气高效成藏模式探讨

High efficient reservoir accumulation models of natural gas of Xujiahe Formation in northeastern Sichuan Basin

为弄清川东北不同地区的成藏差异,并深化川东北地区须家河组致密砂岩气高产富集规律,寻找天然气高产富集区带,从烃源岩、气源、构造、生储组合等几个方面对川东北地区须家河组的成藏模式及特征进行了研究。结果表明:由于生储组合方式及局部构造带变形程度的不同,川东北地区须家河组共发育3种高效成藏模式,分别为陆相弱变形区的"源储共生、源内充注"模式,陆相强变形区的"近源充注、断砂输导"模式以及海-陆相叠加强变形区的"双源供烃、立体输导"模式。依据所建立的3种高效成藏模式,预测元坝西部须三段、元坝中部须四段、马路背地区须二段等是川东北地区须家河组有望实现天然气高效勘探开发的有利目标。

In order to figure out the differences of gas accumulation among different areas, deepen the study of the mechanisms of tight sand gas accumulation of Xujiahe Formation in northeastern Sichuan Basin, and find enri- chment and high production zone of natural gas, the reservoir accumulation model and characteristics of Xujiahe Formation in northeast Sichuan Basin were studied in the aspects of source rock, gas source, structure, and source- reservoir assemblage. The result shows that controlled by different types of source-reservoir assemblage and dif- ferent tectonic deformation degree of local structure belts, there exists three types of high efficient reservoir accu- mulation models in Xujiahe Formation： coexisting source and reservoir model in continental weak deformation zone, near source accumulation and fault-sand pathway model in continental strong deformation zone, and double- source supply and 3D network pathway model in continental-marine strong deformation zone. Based on these three accumulation models, the third member of Xujiahe Formation in western Yuanba area, the fourth member of Xujiahe Formation in central Yuanba area and the second member of Xujiahe Formation in Malubei area are the favorable target zones for the high efficient exploration and development in northeastern Sichuan Basin.