鄂尔多斯盆地东部深层煤层气成藏地质条件分析

       鄂尔多斯盆地东部目前的煤层气开发深度浅于1200 m，丰富的深部煤层气资源有待勘探开发。鉴于此，本文分析了 区内深部煤层赋存特征、热演化程度、煤层含气量及其分布规律。认为上古生界埋深的总体分布格局与两个向西凸出浅埋 带的叠加，可能导致煤层含气性和渗透性区域分布格局的进一步复杂化。发现上古生界煤阶区域分布格局与煤层埋深类似， 指示深成变质作用对区域煤阶分布起着主要控制作用。预测了深部煤层含气量的分布格局，认为煤层埋藏一旦超过临界深 度时煤层含气量随深度的加大反而有所降低。建立了自生自储、内生外储两类煤成气藏模式，认为吸附型煤层气藏与游离 型煤成气藏的共生为合采提供了丰厚的资源条件。

Analysis of Geological Conditions of Deep Coalbed Methane Reservoiring in the Eastern Ordos Basin

      Burial depth of the developing coalbed methane (CBM) fields in the eastern Ordos Basin is less than 1200 m. Abundant
deep CBM resources need to be explorated and developed. For this reason, occurrence, coal-rank, CBM content and distribution
of deep coal seams in the eastern Ordos Basin were analyzed. It was suggested that the regional distribution pattern of the gasbearing
characteristics and permeability of depth coal seams might be further complicated due to the overlay of two westward
protruding shallow zone to overall depth pattern of the Upper Paleozoic. It was found that the regional coal-rank occurrence of
the Late Paleozoic coal seams is similar to that of coal seam depth, which indicates a major control of deep burial metamorphism
to the coal rank setting. Occurrence of deep CBM content was predicted. It was suggested that the content might decrease with
the increase of the depth once the burial depth of coal seam exceeds a critical depth. Two types of coal-derived gas reservoir
models were set up including self-generation plus self-storage, endogenous generation plus exogenetic storage. It was suggested
that the paragenesis of both adsorption CBM and free coal-derived gas reservoirs provides a viable resource for the gas combined
development.