沁水盆地高阶煤煤层气开发再认识

Latest understandings of the CBM development from high-rank coals in the Qinshui Basin

近年来,中国的煤层气产业出现了徘徊不前的颓势,单井产量低、核心技术瓶颈没有突破是制约其发展的主要原因。为此以沁水盆地煤层气开发现状为依据,从资源的可动用性、勘探评价程序的合理性、煤层采出水与注入水的利弊、煤层气开发井型等4个方面对高阶煤煤层气开发进行了深入分析,并得到4点新认识:①我国煤层气资源评价的核心是可动用性;②煤层气资源动用的决定因素是"三性"(解吸性、扩散性和渗透性);不同区块"三性"指标的优劣有所不同,这也表明不同区域制约煤层气高产的主控因素各不相同,既有单因素的,也有多因素耦合的结果;③要辩证看待"水力压裂"对煤层的改造与伤害,针对煤层"三性"短板特性的改造方式是提高煤层气单井产量的关键;④水平井是煤层气田高效开发最重要的手段之一,需要针对不同煤岩特点开展井型与无污染完井方式联合攻关。

In recent years, the coalbed methane （CBM） industry in China has experienced staggering development predominantly due to the low productivity of individual wells and no breakthroughs in core technologies. With consideration to the present development of CBM in the Qinshui Basin, an in-depth analysis was made on the development of CBM from high-rank coals in the aspects of recoverability of resources, rationality of exploration and assessment programs, benefits and drawbacks of produced and injected water, and configurations of wells for CBM development. New understandings were gained in the following four aspects. （1） Recoverability is the core in the assessment of CBM resources in China. （2） Desorption, diffusion and permeability are the top three decisive factors for the development of CBM resources. Different blocks may have different properties in these three factors. In other words, different blocks may have one or more different factor（s） that may constrain the high efficient development of CBM. （3） ＂Hydraulic fracturing＂ is a double-edged sword for CBM development, because it may re-construct and damage reservoir formations simultaneously. To enhance productivity, the key is to identify optimal techniques to cope with the specific unfavorable properties of CBM reservoirs. （4） Horizontal wells are very important for high-efficient CBM development. More researches are required to determine the optimal combination of well configurations and contamination-free completion for CBM reservoirs with specific properties.