贵州省煤层气规划区块煤储层特征与有利区优选

Characteristics of coal reservoirs and favorable areas classification and optimization of CBM planning blocks in Guizhou Province

煤层气有利区块的科学评价,是煤层气勘探开发部署和效益最大化。基于贵州省新划定的18个矿权空白的煤层气规划区块,综合区块现有地质与工程数据,系统研究了18个区块煤层气地质背景、资源特征、赋存特征和储层特征,并基于煤阶分类评价原则,运用多层次模糊数学综合评判法对18个区块进行了区块优选。结果表明:(1) 18个规划区块龙潭组煤层形成于海陆过渡相沉积环境,构造条件相对复杂,煤阶变化范围宽,煤储层地域性特征明显,具有薄-中厚煤层发育、含气量高、储层能量高但渗透率低的总体特征;(2)建立了高阶煤煤层气、中阶煤煤层气有利区分类优选方法,基于不同类型煤层气评价指标体系不同的方法原则,优选了15个选区评价参数,采用层次分析法获得参数权重,并建立各参数隶属度函数,结合模糊综合评判法确定评价样本得分,得到综合评价系数;(3)根据综合评价系数,划分出有利区3个、次有利区6个、后备区9个,其中中阶煤煤层气大河边向斜区块、照子河向斜盘北区块和高阶煤煤层气大方背斜南段区块为煤层气勘探开发有利区。评价结果为未来贵州省煤层气整体有序的勘探开发工作部署提供支持。

The scientific evaluation of favorable CBM blocks concerns the deployment of CBM exploration and development and the maximization of benefits. On the basis of the existing geological and engineering data, the geological background, resource characteristics, occurrence characteristics and reservoir characteristics of CBM are studied in the18 blocks with unregistered mining rights in Guizhou Province. According to the principle of coal rank classification and evaluation, the optimum block among the 18 blocks is selected by using the multi-level fuzzy comprehensive evaluation method. The results are as follows.(1) The coal seams of Longtan Formation in the 18 planning blocks of Guizhou Province are formed in the marine-continental transitional sedimentary environment. With relatively complex tectonic conditions, a wide range of coal rank variations, and obvious regional characteristics of coal reservoirs, they are characterized by the development of thin-medium thickness coal seams, high gas content, high reservoir energy and low permeability.(2) The method for the classification and optimization of favorable areas of medium-and high-rank CBM is established. 15 evaluation parameters are selected based on the different methods and principles of different CBM evaluation index systems. The weights of parameters are obtained by the analytic hierarchy process, and the membership function of each parameter is established. The scores of evaluation samples are determined by the fuzzy comprehensive evaluation method, and then the comprehensive evaluation coefficient is obtained.(3) By using the coefficient, three favorable areas, five sub-favorable areas and nine backup areas are identified, among which, Dahebian syncline block of medium-rank CBM, Zhaozihe syncline north block, and southern section of Dafang anticline block of high-rank CBM are favorable areas for CBM exploration and development. The evaluation results provide support for the overall and orderly deployment of CBM exploration and development in Guizhou Province in the future.