水合物藏注熱開采數(shù)值模擬及熱前緣分析
發(fā)布時間：2019-01-05 16:34
【摘要】：在水合物藏注熱開采過程中,同時考慮分解區(qū)和水合物區(qū)的傳熱規(guī)律對于定量理解水合物分解過程中的傳熱以及熱開采效率評價等有著重要的作用。因此,研究分解前緣的移動規(guī)律是有必要的。本文利用CMG-STARS建立了天然氣水合物開采數(shù)值模型,模型中考慮了水合物分解動力學,質(zhì)量守恒,能量守恒,熱傳導和熱對流。通過與室內(nèi)實驗擬合得到模型關(guān)鍵參數(shù),將建立的數(shù)值模型與TOUGH-Fx,Mallik水合物藏開采試驗數(shù)據(jù)進行擬合,擬合效果較好,驗證了軟件的可靠性。研究結(jié)果表明:降壓產(chǎn)生的分解前緣移動較慢,注熱產(chǎn)生的分解前緣移動速度相對較快,熱對流起主導作用,熱傳導作用較弱。對影響分解前緣移動的因素進行分析,包括地質(zhì)因素和開采因素。地質(zhì)因素中敏感性較強的因素為初始水合物飽和度,地層孔隙度,較弱的因素為地層絕對滲透率,巖石導熱系數(shù),高飽和度(Sh≥0.6)、高孔低飽和度的水合物藏不適合注熱水驅(qū)替;對開采因素的分析表明,影響水合物藏分解前緣移動的主要因素是生產(chǎn)井井底壓力以及注入熱水的溫度和時間,相同注熱量下注水速率對分解前緣移動的影響較小。針對Mallik天然氣水合物藏特征,分別進行了單井降壓開采及兩口井降壓注熱聯(lián)合開采。單獨降壓開采中,射開層位出現(xiàn)明顯的分解前緣;聯(lián)合開采中,生產(chǎn)層位由上到下,分解前緣移動距離逐漸增大;上部層系水合物藏初始水合物飽和度較低,地層絕對滲透率較大,同時能夠得到蓋層傳導的熱量,上部層系水合物分解情況較好,下部層系分解情況相對差一些。
[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，
本文編號：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，
本文編號：2402024
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