鄂尔多斯盆地中东部地区上古生界天然气储藏系统形成特征

对鄂尔多斯盆地中东部地区上古界的气源进行了对比，分析了该区域的地质条件。鄂尔多斯盆地中东部地区上古生界为独立的天然气系统，上古生界气藏形成受多种因素的控制。该区天然气藏主要为岩性气藏，其分布受沉积特征控制，其中本溪组山２段气藏由储集体决定；山１段盒７段气藏受盖层质量控制；盒６段上石盒子组气藏较少。其原因在于其中的泥岩受异常高压的阻止作用，也因为层位较高，从气源岩到达的气量较少。

GAS OCCURRENCE OF UPPER PALEOZOIC PETROLEUM SYSTEM IN MIDDLE EASTERN ORDOS BASIN

pper Paleozoic system in middle easterm Ordos basin is an independent natural system, in which the P 2sh P 2s formations act as the regional caprocks, the C 2b formation acts as the bottom partition. The coals, argillaceous limestones and mudstones in C 3t-C 2b-P 1s formation constitute the source rocks of the gas. Stratigraphic reservoirs resulting from the deposition-facies change and a distributed in the system over the whole middle eastern area,which represents a stable intracatonic setting with a transition environment from shallow marine to continental. Gas reservoirs in the system are divided into three plays. The occurrence of gas reservoirs in C 3t-C 2b-P 1s 1 formation depends on where the porosity developed, and in P 1s 2-P 2x 8-P 2x 7 formations on where the seal rocks developed. The sections of P 2x 6 and the upper possess few accumulations, because higher pressure built up in the mudstones and also because few gases could reach from the lower sourec rocks.