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淮北煤田煤成气低渗砂岩储层综合评价研究

Study on comprehensive evaluation of low permeability sandstone reservoirs ofcoal-derived gas in Huaibei Coalfield

  • 摘要: 煤成气是天然气资源的重要补充,淮北煤田煤成气资源丰富,勘探潜力较大,但煤气对低渗砂岩储层研究,进行储层评价更少,为了有效评价淮北煤田二叠系山西组、下石盒子组和上石盒子组砂岩低孔低渗储层,利用孔渗测试、岩石薄片分析、扫描电镜等方法,以沉积相、孔渗特征、孔隙结构、孔隙类型及成岩作用等为评价参数,对其进行了综合评价。结果表明:从孔渗性和孔隙结构看,上石盒子组最好,其次为山西组,下石盒子组较差;从孔隙发育程度和类型看,上石盒子组孔隙最发育,主要为原生孔隙和次生溶孔,其次是山西组,主要为次生溶孔,而下石盒子组孔隙发育较差;综合评价看,上石盒子组砂岩储层发育最好,Ⅰ类储层占22.65%,Ⅱ类储层占50.32%,Ⅲ类储层占27.03%;其次为山西组砂岩储层,Ⅰ类储层占21.7%,Ⅱ类储层占42.05%,Ⅲ类储层占36.25%;而下石盒子组砂岩储层较差,Ⅰ类储层占2.91%,Ⅱ类储层占38.85%,Ⅲ类储层占58.24%。

     

    Abstract: Coal-derived gas is an important supplement to natural gas resources. The Huaibei Coalfield is rich in coal-derived gas resources and has great exploration potential. However, the study of low permeability sandstone reservoirs is limited, and there is also less reservoir evaluation. In order to effectively evaluate sandstone low-porosity and low-permeability reservoirs of Shanxi Formation, Lower Shihezi Formation and Upper Shihezi Formation in Huaibei Coalfield, the sedimentary facies, pore permeability characteristics, pore structure, pore types and diagenesis were comprehensively evaluated by means of pore permeability test, rock slice analysis and scanning electron microscope. The results show that from the perspective of pore permeability and pore structure, the Upper Shihezi Formation is the best, followed by the Shanxi Formation, and the Lower Shihezi Formation is poor. From the perspective of the degree and type of pore development, the Upper Shihezi Formation has the most developed pores, mainly primary pore and secondary dissolution pore, followed by Shanxi Formation, mainly secondary dissolution pore, while the Lower Shihezi Formation has poor pore development. Comprehensive evaluation shows that sandstone reservoirs in Upper Shihezi Formation have the best development. Type Ⅰ reservoirs account for 22.65%, Type Ⅱ reservoirs account for 50.32%, and Type Ⅲ reservoirs represent 27.03%;This was followed by Shanxi sandstone reservoirs, where Type I reservoirs account for 21.7%, Type Ⅱ reservoirs account for 42.05%, and Type Ⅲ reservoirs shares another 36.25%; The sandstone reservoir of Lower Shihezi Formation is poorer, with Type Ⅰ reservoir accounting for 2.91%, Type Ⅱ reservoir accounting for 38.85%, and Type Ⅲ reservoir accounting for 58.24%.

     

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