高煤阶储层煤层气解吸滞后现象定量表征及其对开发的影响
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摘要
通过理论推理提出了残余吸附气量和解吸滞后系数2个定量表征指标,并通过甲烷等温吸附、解吸实验进行了验证,在此基础上分析了解吸滞后对煤层气开发的影响。结果表明,基于残余吸附气量改造后的Langmuir吸附模型适用于高煤阶煤储层等温解吸数据的拟合;残余吸附气量和解吸滞后系数能够定量表征煤层气解吸滞后程度;煤样残余吸附气量和解吸滞后系数受储层物性特征影响,渗透率越低,孔隙半径越小,比表面积越大,残余吸附气量和解吸滞后系数越大。解吸滞后现象导致煤储层实际解吸压力降低,需要用等温解吸曲线来推算实际的解吸压力,且解吸滞后大大降低了煤层气的采出程度和解吸效率。
This paper proposes two quantitative characterization indexes, such as residual adsorption gas content and desorption hysteresis coefficient through theoretical reasoning. And the two indexes are verified by the isothermal adsorption and desorption experiments. On this basis, the influence of desorption hysteresis on CBM development is analyzed. The results show that the modified Langmuir adsorption model is suitable for fitting the isothermal desorption data of high rank coal reservoirs. Residual adsorption gas contents and desorption hysteresis coefficient can be used to characterize quantitatively the degree of desorption hysteresis. The residual adsorption gas content and desorption hysteresis coefficient of coal samples are affected by reservoir physical properties. The lower the porosity and permeability, the smaller the pore radius and the larger the specific surface area of coal samples, the greater the residual adsorption gas content and desorption hysteresis coefficient. The phenomenon of desorption hysteresis leads to the decrease of actual desorption pressure in coal reservoirs. It is necessary to use isothermal desorption curve to calculate the actual desorption pressure.
This paper proposes two quantitative characterization indexes, such as residual adsorption gas content and desorption hysteresis coefficient through theoretical reasoning. And the two indexes are verified by the isothermal adsorption and desorption experiments. On this basis, the influence of desorption hysteresis on CBM development is analyzed. The results show that the modified Langmuir adsorption model is suitable for fitting the isothermal desorption data of high rank coal reservoirs. Residual adsorption gas contents and desorption hysteresis coefficient can be used to characterize quantitatively the degree of desorption hysteresis. The residual adsorption gas content and desorption hysteresis coefficient of coal samples are affected by reservoir physical properties. The lower the porosity and permeability, the smaller the pore radius and the larger the specific surface area of coal samples, the greater the residual adsorption gas content and desorption hysteresis coefficient. The phenomenon of desorption hysteresis leads to the decrease of actual desorption pressure in coal reservoirs. It is necessary to use isothermal desorption curve to calculate the actual desorption pressure.
引文
[1]李相方,蒲云超,孙长宇,等.煤层气与页岩气吸附/解吸的理论再认识[J].石油学报,2014,35(6):1113.
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[5]张遂安,叶建平,唐书恒,等.煤对甲烷气体吸附解吸机理的可逆性实验研究[J].天然气工业,2005,25(1):44-49.
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[7]马东民,张遂安,蔺亚兵.煤的等温吸附-解吸实验及其精确拟合[J].煤炭学报,2011,36(3):477-480.
[8]关富佳,张杰,王海涛,等.川东龙马溪组页岩解吸滞后现象实验研究[J].西安石油大学学报(自然科学版),2017,32(1):71-74.
[9]马东民,李卫波,蔺亚兵.降压解吸关系式在中高阶煤煤层气排采中的应用[J].西安科技大学学报,2010,30(6):697-701.
[10]贾慧敏.高煤阶煤岩孔隙结构分形特征研究[J].石油化工高等学校学报,2016,29(1):53-56.
[2]庞源.瓦斯解吸滞后效应影响因素及其机理试验研究[D].徐州:中国矿业大学,2015.
[3]谢勇强.低阶煤煤层气吸附与解吸机理实验研究[D].西安:西安科技大学,2006.
[4]马东民,韦波,蔡忠勇.煤层气解吸特征的实验研究[J].地质学报,2008,82(10):1432-1436.
[5]张遂安,叶建平,唐书恒,等.煤对甲烷气体吸附解吸机理的可逆性实验研究[J].天然气工业,2005,25(1):44-49.
[6]吴迪,孙可明,肖晓春,等.块状型煤中甲烷的非等温吸附-解吸试验研究[J].中国安全科学学报,2012,22(12):122-126.
[7]马东民,张遂安,蔺亚兵.煤的等温吸附-解吸实验及其精确拟合[J].煤炭学报,2011,36(3):477-480.
[8]关富佳,张杰,王海涛,等.川东龙马溪组页岩解吸滞后现象实验研究[J].西安石油大学学报(自然科学版),2017,32(1):71-74.
[9]马东民,李卫波,蔺亚兵.降压解吸关系式在中高阶煤煤层气排采中的应用[J].西安科技大学学报,2010,30(6):697-701.
[10]贾慧敏.高煤阶煤岩孔隙结构分形特征研究[J].石油化工高等学校学报,2016,29(1):53-56.