煤岩气藏开发分类探讨

DISCUSSION ON CLASSIFICATION OF COALBED METHANE RESERVOIRS FOR DEVELOPMENTS

煤岩气藏在孔隙结构、天然气赋存方式和产出机理方面均表现出区别于其它气藏的特殊性。已经形成的关于煤岩气藏分类主要用于指导勘探和选区评价 ,随着国外煤层气开发成功的气藏类型逐渐增多 ,特别是我国开发试验区规模和数量的扩大 ,综合各类气藏的主要特征和影响开发效果的主控因素 ,提出区别于选区评价及勘探的煤岩气藏开发分类具有重要的意义。主要考虑煤层厚度、渗透率、含气饱和度和裂隙含水状况等因素 ,对煤岩气藏进行分类。实例分析表明 ,类似圣胡安、黑勇士盆地的中、高渗煤岩气藏的开发问题已基本解决 ,低渗、致密煤岩气藏开发是今后的主攻方向 。

Coalbed methane(CBM) reservoirs are characterized with specialties in pore structures, gas occurrences and production mechanisms different with conventional and other unconventional gas reservoirs. The classifications of CBM reservoirs in publishing are usually proposed for direction of exploration and evaluation of candidate areas. With the progress of economically developments of various types of CBM reservoirs in overseas, especially with the rapid increases in quantity and scale of pilot tests in china, it is of important significance to discuss the classifications of CBM reservoirs for developments which comprehensively considers particularities and common properties of different kinds of CBM reservoirs, as well as major factors related to development efficiencies. The classifications of CBM reservoirs for developments are presented in the light of thickness of coalbeds, permeability, gas saturation in matrix and water saturation in natural fractures. Case studies show that fundamental problems on CBM developments related to reservoirs with high and medium permeability have been solved. As the fact that there are some key theoretical and technological questions retarded CBM developments of low permeability and tight reservoirs, solving these questions are the main directions for R&D in the future.