川东北地区二叠系长兴组生物礁类型及控制因素

The Controlling Factors and Types of Carbonate Reef of Permian Changxing Formation in Northeast of Sichuan Basin

川东北地区二叠系长兴组生物礁内蕴含大量的天然气,为该区主力储层之一。长兴组生物礁类型有台地边缘礁和浅缓坡生物礁,均出现在高位期,主要分布在梁平-开江陆棚两侧。陆棚东侧是以普光地区为代表的台地边缘礁,西侧是以元坝地区为代表的浅缓坡生物礁。与浅缓坡生物礁相比,台地边缘礁具有规模大、期次少、造礁生物相对单一的特点。生物礁类型的差异主要受控于构造作用和沉积作用,构造作用的差异决定了生物礁发育的潜力,而沉积作用则决定了生物礁的规模。

Organic reefs of Permian Changxing Formation have been the main reservoir in northeast of Sichuan Basin.The reef types of Permian Changxing Formation are shelf margin reef and shallow ramp reef which are distributed in both sides of Liangping-Kaijiang shelf.The shelf margin reef developed in Puguang area while shallow ramp reef developed in Yuanba area.Most reefs of Permian Changxing Formation appeared at highstand stage.Compared with shallow ramp reef,shelf margin reef had the characteristics of larger scale,less reef-building stages and relatively homogeneous reef-building organisms.The reef type was controlled by tectonics and sedimentation.The tectonic difference controlled the potential of reef and the sedimentary difference controlled the scale of reef.