中国中西部前陆盆地的地质特征及油气聚集

Geological features and petroleum accumulation in the foreland basins in central and western China

中国中西部前陆盆地具有十分丰富的油气资源,近年来油气勘探也取得了很大的成果,但总体上来说其地质情况复杂、研究程度较低。世界上典型的前陆盆地一般位于造山带和稳定的克拉通之间的狭长槽地,而在中国中西部则主要为与古特提斯造山带在新特提斯阶段再活动有关的陆内会聚形成的“再生”前陆盆地,因此与世界典型前陆盆地相比中国中西部前陆盆地具有一定的“特殊性”。根据两期前陆的叠合程度差异造成的盆地几何形态、挠曲沉降、地层层序、沉积充填、构造变形特征的特点,将中国中西部前陆盆地归纳为改造型、新生型、叠加型和早衰型四种组合类型的前陆盆地。中西部不同组合类型前陆盆地具有不同的结构特征,决定了不同组合类型前陆盆地成藏特征和油气勘探潜力上的差异。

There are abundant oil and gas resources in the foreland basins in central and western China. Many outstanding successes of petroleum exploration have been obtained recently in that region. However, the exploration activity is rare because of the complex geology in the foreland basins. A classical foreland basin overseas is a linear depression located between the active orogen and stable craton. Nevertheless, in central and western China, there are mainly rejuvenated foreland basins resulting from convergence within the craton, related to the reactivation of old Tethys tectonic domains during the new Tethys stage. Therefore, there are many differences in comparison with the classical foreland basin abroad. The difference, due to the superimposition of foreland structures of two periods, is responsible for differences in basin geometry, in plate flexure and subsidence, in sedimentation, and in structural deformation. According to these differences, we have classified the foreland basins in central and western China into four types, i. e. , alteration foreland basin, palingenetic foreland basin, superposition foreland basin and caduceus foreland basin. They have different structural characteristics that determine the different reservoir features and the variable exploration potential for these three types of foreland basin.