鄂尔多斯盆地上古生界非常规含气系统

指出:鄂尔多斯盆地中东部上古生界煤层厚度大,煤岩中镜质组含量普遍较高(处于中―高变质程度),构造演化与应力场作用使煤层割理发育、渗透率较高、煤层吸附强度大,具有相对稳定的水动力场分布和顶底板盖层,形成了有利的煤层气系统;盆地中部在丰富的气源、砂岩成岩致密化早于主供气期、成藏后构造及水动力稳定等成藏条件配合下形成了大型深盆气系统。认为上古生界煤层气富集区亦是深盆气的重要气源补充区。

UNCONVENTIONAL GAS SYSTEM OF UPPER PALEOZOIC IN ORDOS BASIN

Upper Paleozoic of Ordos basin is prolific in unconventional natural gas. In the central-eastern basin, coal seam in Upper Paleozoic are characterized by thick layers, high vitrinite content and middlehigh coal rank. Influenced by the structural evolution and stress field, cleats are well developed within coal seam and thus the reservoir permeability is high. With the high absorption intensity, stable hydrodynamic field and coal-seam floor and roof, favorable coalbed gas system is formed. Abundant gas source rocks are develop in the central basin. Compaction process of sandstones is prior to the mass gas expulsion period of gas source rocks. Structure movement and hydrodynamics after the formation of reservoirs are relatively stable. Vast deep basin gas traps are formed in combination with these reservoir-forming conditions. Researches on reservoir-forming indicate that areas enriched with coalbed gas in Upper Paleozoic are important gas supplements to deep basin gas traps.