【摘要】：近年來(lái),隨著常規(guī)能源的日益枯竭和碳排放的增加,頁(yè)巖氣等非常規(guī)能源的開發(fā)成為世界能源研究的焦點(diǎn)之一。目前對(duì)于儲(chǔ)層變形與氣體運(yùn)移機(jī)制的研究尚不成熟,這極大地限制了頁(yè)巖氣開采技術(shù)的發(fā)展。本文基于多孔彈性力學(xué)和滲流力學(xué)等理論,建立了頁(yè)巖三重孔隙結(jié)構(gòu)下包含頁(yè)巖變形、干酪根基質(zhì)分子解吸與擴(kuò)散、無(wú)機(jī)質(zhì)系統(tǒng)粘性流、以及裂隙系統(tǒng)粘性流的多物理場(chǎng)耦合模型。此外,建立了多孔吸附介質(zhì)的有效應(yīng)力準(zhǔn)則。主要取得以下研究成果。(1)提出多孔含裂隙頁(yè)巖儲(chǔ)層的三重孔隙力學(xué)模型。根據(jù)氣體在頁(yè)巖中的運(yùn)移及吸附儲(chǔ)存特征,建立了頁(yè)巖儲(chǔ)層的三重孔隙度數(shù)學(xué)模型以及各自系統(tǒng)的擴(kuò)散和滲透率數(shù)學(xué)模型,并建立了三重孔隙結(jié)構(gòu)下有效應(yīng)力及吸附膨脹引起的變形控制方程、干酪根基質(zhì)系統(tǒng)的氣體擴(kuò)散控制方程、無(wú)機(jī)質(zhì)系統(tǒng)以及裂隙系統(tǒng)的流動(dòng)控制方程�？刂品匠讨邪隧�(yè)巖變形、氣體滲流、氣體吸附等多物理場(chǎng)耦合作用。(2)揭示了由于三重介質(zhì)導(dǎo)流能力的差異而引起的壓力場(chǎng)演化不同步現(xiàn)象:裂隙快于無(wú)機(jī)質(zhì),并快于干酪根。研究結(jié)果表明產(chǎn)氣過(guò)程中氣體的交換類型屬于干酪根-無(wú)機(jī)質(zhì)-裂隙的“串聯(lián)”流動(dòng)模式:氣體由濃度高(壓力較大)的有機(jī)孔向無(wú)機(jī)質(zhì)系統(tǒng)擴(kuò)散,再由無(wú)機(jī)質(zhì)系統(tǒng)向裂隙系統(tǒng)(壓力較小)流動(dòng);但當(dāng)干酪根基質(zhì)的擴(kuò)散系數(shù)相對(duì)較大時(shí),其壓力演化幾乎與無(wú)機(jī)質(zhì)同步,且均慢于裂隙系統(tǒng)的壓力演化,此時(shí)氣體的交換類型服從“并聯(lián)”模式:裂隙系統(tǒng)中的氣體同時(shí)來(lái)源于干酪根和無(wú)機(jī)質(zhì)系統(tǒng)。(3)通過(guò)與現(xiàn)場(chǎng)水平井產(chǎn)氣率的匹配,驗(yàn)證了該模型的數(shù)值模擬結(jié)果。敏感性分析結(jié)果表明,裂隙滲透率對(duì)初始產(chǎn)氣率的影響至關(guān)重要,而干酪根基質(zhì)的TOC含量和擴(kuò)散系數(shù)是保證頁(yè)巖氣持續(xù)高效開采的重要參數(shù)。(4)通過(guò)引入吸附膨脹模量的概念,建立了考慮吸附膨脹效應(yīng)下多孔吸附介質(zhì)的有效應(yīng)力準(zhǔn)則,將多孔吸附介質(zhì)的非線性變形問(wèn)題簡(jiǎn)化成無(wú)孔非吸附介質(zhì)的線彈性變形問(wèn)題,并通過(guò)煤體的無(wú)約束實(shí)驗(yàn)和單軸應(yīng)變實(shí)驗(yàn)證明了有效應(yīng)力系數(shù)的統(tǒng)一性。(5)吸附膨脹模量是衡量多孔吸附介質(zhì)吸附變形難易程度的指標(biāo)。吸附膨脹模量越小,相同孔壓情況下的吸附膨脹越明顯。實(shí)驗(yàn)證明低孔壓條件下(7 MPa),煤體對(duì)甲烷或二氧化碳的吸附膨脹模量比固體顆粒體積模量小一個(gè)數(shù)量級(jí),這側(cè)面反映了低孔壓儲(chǔ)層產(chǎn)氣過(guò)程中的吸附效應(yīng)對(duì)變形或滲透率的影響占主導(dǎo)地位。
[Abstract]:In recent years, with the depletion of conventional energy and the increase of carbon emissions, the development of unconventional energy such as shale gas has become one of the focuses of energy research in the world. At present, the study of reservoir deformation and gas migration mechanism is still immature, which greatly limits the development of shale gas production technology. Based on the theory of porous elasticity and percolation mechanics, this paper has established shale deformation, molecular desorption and diffusion of kerogen matrix, viscous flow in inorganic system under shale triple pore structure. And the multi-physical field coupling model of viscous flow in fracture system. In addition, the effective stress criterion for porous adsorption media is established. The main achievements are as follows: (1) the triple pore mechanics model of porous fractured shale reservoir is proposed. According to the characteristics of gas migration and adsorption and storage in shale, the mathematical model of shale reservoir's triple porosity and the mathematical model of diffusion and permeability of their respective systems are established. The governing equations of effective stress and adsorption expansion under triple pore structure, gas diffusion control equation of kerogen matrix system, flow control equation of inorganic system and fracture system are established. The governing equation includes the coupling of shale deformation, gas percolation and gas adsorption. (2) it is revealed that the evolution of the pressure field is out of sync due to the difference in the conductivity of the triplet medium: the fracture is faster than the inorganic mass. And faster than kerogen. The results show that the type of gas exchange in the process of gas production belongs to the "series" flow pattern of kerogen, inorganic substance and fissure: the gas diffuses from organic pores with high concentration (high pressure) to inorganic system. However, when the diffusion coefficient of cheese is relatively large, the pressure evolution is almost synchronized with inorganic matter, and both of them are slower than the pressure evolution of fracture system. At this time, the gas exchange type follows the "parallel" model: the gas in the fracture system comes from both kerogen and inorganic system. (3) the numerical simulation results of the model are verified by matching the gas production rate of the field horizontal well. The sensitivity analysis results show that the influence of fracture permeability on the initial gas production rate is very important, and the TOC content and diffusion coefficient of the kerogen are important parameters to ensure the shale gas sustainable and efficient production. (4) the concept of adsorption modulus of expansion is introduced. In this paper, the effective stress criterion of porous adsorption medium considering the effect of adsorption and expansion is established, and the nonlinear deformation problem of porous adsorption medium is simplified as the linear elastic deformation problem of porous non-adsorbed medium. The unity of effective stress coefficient is proved by unconstrained and uniaxial strain tests. (5) the adsorption modulus of expansion is an index to measure the difficulty of adsorption deformation in porous adsorption medium. The smaller the modulus of adsorption expansion is, the more obvious the adsorption expansion is at the same pore pressure. The experimental results show that at low pore pressure (7 MPA), the adsorption modulus of expansion of methane or carbon dioxide on coal is one order of magnitude smaller than that of solid particles. This side reflects the dominant effect of adsorption on deformation or permeability during gas production in low pore pressure reservoirs.
【學(xué)位授予單位】：中國(guó)礦業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TE31

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