鄂尔多斯盆地北部大牛地气田成岩成藏耦合关系

鄂尔多斯盆地北部大牛地气田上古生界含气层系多，储量规模大，是一个典型的大型煤成气田。对源岩及天然气地化特征、源岩热演化模拟、储层岩石学、成岩演化及相关成藏要素的综合研究表明，大牛地气田具有“两个生气中心，储层致密化前后分明，早期侧向运移，晚期垂向充注”的成藏模式，形成了研究区内两种不同类型的气藏，即西南角的盒2段和盒3段辫状河道砂体储层气藏和东北角的太2段障壁砂坝储层气藏，生气中心和储层致密化对上古生界天然气成藏有着重要的控制作用。

Coupling relationship between reservoir diagenesis and natural gas accumulation of Daniudi Gas Field in North Ordos Basin

Daniudi Gas Field is a typical and large coal-genetic gas field in North Ordos Basin and has the characteristics of multiple gas-bearing layer series and large-scale explored reserves in Upper Palaeozoic reservoir. The comprehensive analyses on the geochemistry characteristics of source rocks and natural gas, thermal evolution modeling results of source rocks, reservoir petrology, diagenesis evolution and other gas accumulation elements show that Daniudi Gas Field possesses a special gas accumulation model controlled by two gas generating centers and the tightening processes of sandstone and divided by the tightening time of sandstone termination. There developed two kinds of gas reservoir in Daniudi Gas Field. Prior to the tightening time of sandstone termination, the lower maturation gas migrated to the higher traps in large scale under the force of buoyancy and formed the T2 barrier bar facies gas reservoir in the Northeast. Then, the high-maturation gas migrated upward in the fracture systems under the force of gas-generating overpressure and formed H2 and H3 braided channel facies gas reservoir in the Southwest. The gas accumulation center and tightness of sandstone controlled the natural gas accumulation of Upper Palaeozoic reservoir in North Ordos Basin.