高阶煤层气高效开发工程技术优选模式及其应用

高阶煤层气井的平均单井产气量低已成为制约我国煤层气产业发展的主要瓶颈之一,直接导致了煤层气开发经济效益低。为此,基于不同煤储层的地质条件,选择适用于煤层气高效开发的工程技术是提高当前高阶煤层气开发效益的关键。在剖析影响高阶煤层气开发效果的地质因素的基础上,建立了高阶煤层气开发的地质模式,并针对不同的地质模式优选出了相应的开发工程技术。结果表明:(1)影响高阶煤层气开发效果的主要地质因素按其影响程度从小到大依次为:煤体结构、煤岩变质程度、地应力、临储比;(2)据此划分了直井压裂、裸眼多分支水平井、U型和顶板仿树形水平井、鱼骨状和单支型水平井等4种工程地质模式。结论认为:直井压裂和裸眼多分支水平井仅适用于煤体结构好、变质程度高的地区;而低成本、后期可维护、占地面积少的单支型水平井和鱼骨状水平井适用范围广,是适宜大力推广的井型。

Optimal geological–engineering models for highly efficient CBM gas development and their application

Low average single-well production resulting in low economic benefit has become the main bottleneck of the CBM gas development in China. So it is significant to choose suitable efficient development technologies based on CBM geological factors for high-rank CBM recovery enhancement. In view of this, CBM geological factors were analyzed, different geological models were established and the corresponding models of development engineering technologies were thus put forward. It was proposed that the four main factors affecting high-rank CBM recovery from a lower degree to a higher degree respectively include coal structure, vitrinite reflectance, geo-stress, and the ratio of critical desorption pressure to initial reservoir pressure. On this basis, four geological–engineering models were classified as follows: Vertical wells; open-hole and multilateral horizontal wells; U-shaped and tree-like horizontal wells; Fish-bone and L-shaped wells. It is concluded that the former two models are more adaptable in such areas with better coal structures and high degree of thermal maturity, while the latter two are commonly applied in a wide range of areas.