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    黔西北地区上二叠统煤层气有利区优选评价

    Optimization and evaluation of favorable CBM areas in the Upper Peimian of the Northwest Guizhou

    • 摘要:
      研究目的 优选研究区煤层气勘查开发有利区,为贵州省煤层气勘查部署提供参考。
      研究方法 以煤层气勘查资料及实验测试成果为基础,系统分析研究区主煤层(6、14、27号煤层)的厚度、含气量、渗透率、储层压力和煤体结构发育特征,利用五指标法对19个含气区进行了优选评价。
      研究结果 (1)上述三个主煤层具有南西厚,北东薄的厚度变化趋势;煤层含气量平均11.73 m3/t,向斜控气特征典型。(2)区域上划分出7个大含气区,其中煤层含气量大于16 m3/t的地带主要分布于比德-三塘向斜及金龙-黔西-金沙向斜群。(3)煤层试井渗透率平均0.173 mD,属于中-低渗透率煤层,渗透率在横向上由西向东总体趋于降低,纵向上随着层位降低而趋于降低,但在不同煤层之间出现明显波动。(4)试井煤储层压力平均4.98 MPa,压力系数平均0.86,总体上欠压,由东向西方向具有由欠压状态向正常和超压状态转变的趋势。(5)构造煤具有自东向西逐渐增多的趋势,东部煤层以原生结构与碎裂煤为主,西部以碎粒煤与碎粉煤为主。
      结论 优选出Ⅰ级有利区7个,Ⅱ级有利区8个,Ⅲ级有利区4个,认为土城、杨梅树、大河边、水公河、比德、以支塘、金龙(北)等7个向斜为Ⅰ级有利区,是研究区煤层气开发潜力较大的含气构造单元;格目底、金盆、三塘、黔西(北)、金沙、流长、莫老坝7个向斜为Ⅱ级有利区;其余向斜为Ⅲ级有利区。

       

      Abstract:
      This paper is the result of energy exploration engineering.
      Objective The primary goal is to identify and classify favorable areas for CBM exploration and development, providing a scientific basis for future exploration efforts in Guizhou Province..
      Methods Based on geological exploration data and laboratory sample analyses, key reservoir characteristics of the major coal seams (No. 6, No. 14, and No. 27) were systematically assessed. Parameters such as coal seam thickness, gas content, permeability, reservoir pressure, and coal−body structure were analyzed. Using a five−index evaluation method, 19 gas−bearing areas were classified.
      Results (1) The three major coal seams exhibit greater thickness in the southwest and thinner deposition toward the northeast. The average gas content is 11.73 m³/t, with gas accumulation primarily controlled by synclinal structures. (2) Seven extensive gas−bearing areas were identified, with the Bide−Santang Basin and the Jinlong−Qianxi−Jinsha syncline group exhibiting gas contents exceeding 16 m3/t. (3) The average well−tested permeability of the coal seams is 0.173 mD, indicating a medium−low permeability reservoir. Permeability decreases from west to east and with increasing depth, with significant variations across different seams. (4) The average reservoir pressure is 4.98 MPa, with an average pressure coefficient of 0.86, indicating a predominantly underpressured state. A transition from underpressure to normal and overpressure is observed from east to west. (5) Coal structural characteristics vary spatially, with primary and fragmented coal types dominant in the east, while granulated and pulverized coal types are more prevalent in the west.
      Conclusion Based on the evaluation, seven Grade I, eight Grade II, and four Grade III favorable CBM areas were identified. The Grade I areas, including the Tucheng, Yangmeishu, Dahebian, Shuigonghe, Bide, Zhitang, and northern Jinlong synclines, demonstrate significant CBM exploration and development potential. The Grade II areas include the Gemudi, Jinpen, Santang, northern Qianxi, Jinsha, Liuchang, and Molaoba synclines, while the remaining synclines are classified as Grade III.

       

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