高倾角和“通天”双重特征煤层气勘探思考——以新疆煤层气储层为例

Thinking of CBM exploration with high dip angle and“open air”dual characteristics:A case of Xinjiang CBM reservoir

新疆煤层气储量大,煤层含气量高,但是煤层气井只少数单井持续高产稳产,大部分井低产甚至不产气。因此,新疆煤层气产业难以实现高质量增储上产,达不到规模化开发利用的条件,不能发挥潜在的资源优势。基于对工作实践的认识与分析,结合国内外对煤层气储层的研究成果,认为煤层高倾角+“通天”的空间赋存特征以及针对此特征的技术方案不配套是制约新疆煤层气产业发展的主要因素之一。针对高倾角+“通天”双重特征煤层气储层与低倾角煤层气储层在勘探开发过程中存在的较大差异,分析了煤层气藏出现双重特征的原因并提出以下解决方法:1)借鉴水文地质学和水地球化学研究方法,研究储层的封闭性及其与煤层含气量的关系;2)储层物性参数提取的标准化为储层认识和储层改造决策提供精准依据;3)煤层气成因认定避免了对区域气藏甜点优选、富集规律以及评价工作等的片面认识;4)客观科学的储量计算方法是提高成果转化质量,降低区域性气体储量入库误差的直接方法。该研究结果说明了规范双重特征煤层气储层参数提取和客观识别成藏机理是必要的。

Given the large reserves and high gas content of CBM reservoirs in Xinjiang,a small number of CBM wells have sustained high and stable production,and most wells have low or even no gas production.As a result,it is difficult for Xinjiang CBM industry to increase storage and production with high quality.It cannot reach large-scale development and utilization conditions and cannot give play to potential resource advantages.Based on the practical knowledge analysis,combined with the research results of CBM reservoirs in China and abroad,the author believes that the spatial occurrence characteristics of CBM reservoirs with high dip+“open air”and the technical scheme of this feature are not compatible with one of the main factors restricting Xinjiang coalbed methane industry.In view of the significant difference between the characteristics of the CBM reservoir with high dip+“open air”and the low-dip CBM reservoir,the author puts forward the reasons and solutions to be optimized in the process of exploration and development of CBM reservoirs with dual characteristics from four aspects:1)The sealing property of the reservoir and its relationship with the gas content of CBM reservoirs should be studied using hydrogeology and hydrogeochemistry research methods;2)The standardization of reservoir physical parameters provides accurate basis for reservoir understanding and reservoir reconstruction decision;3)The identification of coalbed methane genesis can avoid one-sided understanding of the regional sweet spot selection,enrichment law,and evaluation CBM reservoirs;4)Objective and scientific reserve calculation method is a direct method to improve the quality of achievement transformation and reduce the error of regional gas storage.It is necessary to standardize the parameters of CBM reservoirs with dual characteristics and objectively identify the accumulation mechanism.