中国煤层气勘探开发战略接替区优选

现阶段中国煤层气探明储量及产量的增长主要依靠沁水盆地南部和鄂尔多斯盆地东缘等几个煤层气产业基地,急需寻找一批勘探开发战略接替区。为此,基于对我国煤层气资源、生储、保存、开发基础等条件的研究成果,总结了影响中国煤层气勘探开发的8个普遍因素(资源丰度、煤层厚度、含气量、原始渗透率、埋藏深度、水文地质条件、煤系沉积环境和地形地貌)和4个关键因素(成因类型、稳定性、后期储层改造和煤体结构破坏程度)。对比分析结果表明:中国西北低煤阶区、东北中低煤阶老工业区和西南中高煤阶构造复杂区,是我国继华北地区之后煤层气产业持续发展的重点区;上述3个重点区的煤层气赋存主控因素分别是成因类型+煤层稳定性、成因类型+岩浆侵入对煤储层改造、煤层稳定性+煤体结构破坏程度,并以此建立了中国煤层气勘探开发战略接替区的优选评价体系。采用多层次模糊数学的方法对上述3个重点区的15个区块进行了评价,共优选出了8个有利接替区和7个较有利接替区,预测煤层气地质资源总量达1.8×10~(13)m~3;8个有利区分别为西北的准东煤田五彩湾—大井地区、吐哈煤田哈密—大南湖地区和陇东煤田,东北的依兰煤田、鹤岗煤田和珲春煤田,西南的川南煤田和水城煤田,它们是近期可以进行煤层气勘探和试验开发的目标区。

Selection of strategic relay areas of CBM exploration and development in China

Currently, the increase in proved reserves and production of coalbed methane mainly comes from several coalbed methane bases in the southern Qinshui Basin and the eastern margin of the Ordos Basin, so there is an urgent need of finding a batch of exploration and development strategic relay areas. Based on the research results in the resources, coal reservoir property, preservation conditions, and development conditions of CBM in China, eight general factors (resource abundance, coalbed thickness, gas content, original permeability, burial depth, hydrogeologic conditions, coalbed depositional environment and landforms) and four critical factors (origin type, stability type, later reservoir reformation and damage degree of coal structure) affecting the CBM reservoir-forming and development conditions were summarized. Comparison shows that the low coal rank area in the northwest, medium-low coal rank area in the northeast, and high coal rank complex structure area in the southwest of China are major relay areas of coalbed methane after northern China areas. Key factors affecting CBM enrichment in the three areas are genetic type & stability of coal seams, genetic type & reconstruction of the reservoir by volcanic intrusion, and stability of coal seams & damage degree of coal structure respectively. Based on these affecting factors, a system for selection and evaluation of relay strategic areas of CBM development has been established. Fifteen blocks in the above three areas have been evaluated by use of multi-layered fuzzy mathematics, out of which eight favorable areas and seven fairly favorable areas have been picked out, with total predicted CBM geological resources of 1.8 trillion m3. The eight favorable areas include the Wucaiwan - Dajing coal exploration area in the Zhundong (eastern Junggar Basin) coalfield, Hami-Dananhu mining area in Turpan-Hami Basin, Longdong (eastern Ningxia) coalfield, Yilan coalfield and Hegang coalfield in Heilongjiang Province, the Hunchun coalfield in Jilin Province, the southern Sichuan coalfield, and the Shuicheng coalfield in Guizhou Province. These favorable areas are CBM gas exploration and pilot development target areas in the near future.