考虑微孔超压环境的煤储层含气量计算方法

发布时间：2018-03-06 10:36

本文选题：煤层气　切入点：含气量　出处：《天然气工业》2017年02期 　论文类型：期刊论文

【摘要】：目前在煤储层含气量的计算过程中,普遍采用测井、试井等得到的储层压力代替气相压力进行反演计算,但由于超压环境下二者不能等同,故导致这一计算结果并不准确。为此,采集山西、河南不同煤级的煤样进行了煤孔隙毛细管压力测试,结合煤层气成藏过程和煤层生排烃史分析了煤储层微孔超压环境的形成机制,据此建立了考虑微孔超压环境的煤储层含气量计算方法,并对河南焦作中马村矿下二叠统山西组二段1号煤层的含气量进行了计算及分析。结果表明:1煤形成演化过程中不断有部分固体有机质转化为气体和水,在其孔隙内必然会出现气水两相界面,由此产生毛细管压力,致使其微孔内气相压力远高于静水柱压力,形成微孔超压赋存环境;2由于微孔超压环境的存在,致使气相压力高于储层压力,基于常规储层压力评价煤储层含气量的计算方法将导致煤储层含气量被低估;3微孔超压环境主要影响3~100 nm孔隙内煤层气含气量的计算,尤其是3~10 nm孔隙,而对于超过100 nm的孔隙则影响不大。结论认为:所建立的煤储层含气量计算方法厘清了煤层气赋存的压力环境,保证了煤储层含气量计算结果的准确性。
[Abstract]:At present, in the calculation process of gas content in coal reservoir, the reservoir pressure obtained by logging and well testing is widely used for inversion calculation instead of gas phase pressure, but the two are not equivalent under overpressure environment. Therefore, the calculation result is not accurate. For this reason, coal samples from Shanxi and Henan provinces have been tested for pore capillary pressure of coal. The formation mechanism of micropore overpressure environment in coal reservoir is analyzed in combination with coalbed methane accumulation process and hydrocarbon generation and expulsion history of coal seam. Based on this, a calculating method of gas content in coal reservoir considering micropore overpressure environment is established. The gas content of No. 1 coal seam in the second stage of Shanxi formation of Lower Permian in Jiaozuo Zhongmaicun Mine, Henan Province, is calculated and analyzed. The results show that some solid organic matter is continuously converted into gas and water during the formation and evolution of No. 1 coal. There is bound to be a gas-water two-phase interface in the pores, resulting in capillary pressure, which causes the gas pressure in the micropore to be much higher than that of the static water column, forming a micropore overpressure environment due to the existence of the micropore overpressure environment. The gas pressure is higher than the reservoir pressure. The calculation method for evaluating the gas content of coal reservoir based on the conventional reservoir pressure will result in the gas content of coal reservoir being underestimated and the overpressure environment of micropore will mainly affect the calculation of the gas content of coal bed gas in the pore of 3 ~ 100 nm. The results show that the calculation method of gas content in coal reservoir clarifies the pressure environment of coalbed methane occurrence and ensures the accuracy of calculation results of gas content in coal reservoir.
【作者单位】：河南理工大学能源科学与工程学院;中原经济区煤层(页岩)气河南省协同创新中心;
【基金】：国家自然科学基金资助项目(编号:41472129、41472127、41502158) 2014年度山西省煤基重点科技攻关项目(编号:MQ2014-01) 山西省煤层气联合研究基金资助项目(编号:2013012004)
【分类号】：P618.13

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