水合物藏注热开采数值模拟及热前缘分析
发布时间：2019-01-05 16:34
【摘要】：在水合物藏注热开采过程中,同时考虑分解区和水合物区的传热规律对于定量理解水合物分解过程中的传热以及热开采效率评价等有着重要的作用。因此,研究分解前缘的移动规律是有必要的。本文利用CMG-STARS建立了天然气水合物开采数值模型,模型中考虑了水合物分解动力学,质量守恒,能量守恒,热传导和热对流。通过与室内实验拟合得到模型关键参数,将建立的数值模型与TOUGH-Fx,Mallik水合物藏开采试验数据进行拟合,拟合效果较好,验证了软件的可靠性。研究结果表明:降压产生的分解前缘移动较慢,注热产生的分解前缘移动速度相对较快,热对流起主导作用,热传导作用较弱。对影响分解前缘移动的因素进行分析,包括地质因素和开采因素。地质因素中敏感性较强的因素为初始水合物饱和度,地层孔隙度,较弱的因素为地层绝对渗透率,岩石导热系数,高饱和度(Sh≥0.6)、高孔低饱和度的水合物藏不适合注热水驱替;对开采因素的分析表明,影响水合物藏分解前缘移动的主要因素是生产井井底压力以及注入热水的温度和时间,相同注热量下注水速率对分解前缘移动的影响较小。针对Mallik天然气水合物藏特征,分别进行了单井降压开采及两口井降压注热联合开采。单独降压开采中,射开层位出现明显的分解前缘;联合开采中,生产层位由上到下,分解前缘移动距离逐渐增大;上部层系水合物藏初始水合物饱和度较低,地层绝对渗透率较大,同时能够得到盖层传导的热量,上部层系水合物分解情况较好,下部层系分解情况相对差一些。
[Abstract]:In the process of hydrate reservoir heat injection extraction, it is important to consider the heat transfer law of decomposition zone and hydrate region for the quantitative understanding of heat transfer in hydrate decomposition process and the evaluation of thermal recovery efficiency. Therefore, it is necessary to study the moving law of the leading edge of decomposition. In this paper, CMG-STARS is used to establish a numerical model of gas hydrate production, in which hydrate decomposition kinetics, mass conservation, energy conservation, heat conduction and thermal convection are considered. The key parameters of the model were obtained by fitting with the laboratory experiments. The numerical model was fitted with the TOUGH-Fx,Mallik hydrate reservoir mining test data. The fitting effect was good and the reliability of the software was verified. The results show that the decomposing front moving slowly, the thermal convection plays the leading role and the heat conduction is weak. The factors affecting the front movement of decomposition are analyzed, including geological factors and mining factors. Among geological factors, the most sensitive factors are initial hydrate saturation, formation porosity, and the weaker factors are formation absolute permeability, rock thermal conductivity and high saturation (Sh 鈮，
本文编号：2402024
[Abstract]:In the process of hydrate reservoir heat injection extraction, it is important to consider the heat transfer law of decomposition zone and hydrate region for the quantitative understanding of heat transfer in hydrate decomposition process and the evaluation of thermal recovery efficiency. Therefore, it is necessary to study the moving law of the leading edge of decomposition. In this paper, CMG-STARS is used to establish a numerical model of gas hydrate production, in which hydrate decomposition kinetics, mass conservation, energy conservation, heat conduction and thermal convection are considered. The key parameters of the model were obtained by fitting with the laboratory experiments. The numerical model was fitted with the TOUGH-Fx,Mallik hydrate reservoir mining test data. The fitting effect was good and the reliability of the software was verified. The results show that the decomposing front moving slowly, the thermal convection plays the leading role and the heat conduction is weak. The factors affecting the front movement of decomposition are analyzed, including geological factors and mining factors. Among geological factors, the most sensitive factors are initial hydrate saturation, formation porosity, and the weaker factors are formation absolute permeability, rock thermal conductivity and high saturation (Sh 鈮，
本文编号：2402024
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