本文選題：煤巖 + 煤層氣�。� 參考：《西南石油大學(xué)》2015年碩士論文

【摘要】：煤層氣是一種清潔能源,我國煤層氣儲量豐富,開發(fā)利用煤層氣資源不僅能有效遏制煤礦瓦斯災(zāi)害,降低甲烷氣體對大氣環(huán)境的溫室效應(yīng),而且可以優(yōu)化我國能源結(jié)構(gòu)、緩解能源短缺問題。然而,由于煤巖的特殊力學(xué)性質(zhì)和煤層氣儲層所處復(fù)雜地質(zhì)環(huán)境特征,煤層氣井壁穩(wěn)定問題嚴(yán)重制約了我國煤層氣資源的勘探開發(fā),其中因煤巖蠕變造成煤層氣井縮徑、卡鉆,甚至井壁的坍塌失穩(wěn)現(xiàn)象尤為突出。本文采用室內(nèi)巖石物理力學(xué)實(shí)驗(yàn)、蠕變模型理論研究及數(shù)值模擬研究等方法,系統(tǒng)和深入地研究了煤層氣儲層井壁煤巖的物理力學(xué)特性、蠕變力學(xué)特性,建立了煤巖彈-粘-塑蠕變模型和基于能量角度的蠕變模型,同時將其與現(xiàn)有巖石蠕變模型進(jìn)行對比,優(yōu)選得到適合描述煤巖蠕變特性的模型。最后,采用COMSOL數(shù)值模擬軟件,分析了受煤巖彈性模量、泊松比、地應(yīng)力分布和井徑變化影響的煤層氣井蠕變規(guī)律。獲得主要結(jié)論如下:(1)通過室內(nèi)物理實(shí)驗(yàn)測試,得到了煤巖的干密度、天然密度、含水率、比表面積、總孔隙體積、平均孔徑等物理性質(zhì)指標(biāo)。分析發(fā)現(xiàn),煤巖總孔體積與比表面積有關(guān),且基本呈線性正相關(guān)。(2)煤巖單軸蠕變力學(xué)實(shí)驗(yàn)顯示,當(dāng)軸向應(yīng)力從0.98MPa增加至5.98MPa時,煤樣試件蠕變過程表現(xiàn)為衰減蠕變;當(dāng)軸向應(yīng)力為6.49MPa時,煤樣試件蠕變過程表現(xiàn)為非衰減蠕變,煤巖的長期強(qiáng)度在5.98~6.49MPa之間。(3)根據(jù)煤巖蠕變力學(xué)實(shí)驗(yàn)結(jié)果,對西原模型進(jìn)行了改進(jìn),獲得了基于煤巖彈-粘-塑性特性的蠕變力學(xué)模型,并推導(dǎo)得到了本構(gòu)方程和蠕變方程。改進(jìn)的西原模型能夠反映煤巖蠕變曲線的二次指數(shù)衰減特征。(4)基于能量角度,提出了煤巖蠕變力學(xué)模型,該模型在西原模型的基礎(chǔ)上串聯(lián)一個繞組δ元件,該元件的特點(diǎn)是在受力情況下應(yīng)變與時間呈t3關(guān)系。并且推導(dǎo)出了基于能量角度的煤巖蠕變力學(xué)模型本構(gòu)方程和蠕變方程。(5)煤層氣儲層井壁煤巖最大蠕變變形方向均為最大水平地應(yīng)力方向,井眼變形呈現(xiàn)出最大主應(yīng)力方向受壓縮而產(chǎn)生大幅縮徑現(xiàn)象。隨著彈性模量的減小,煤層氣井壁煤巖蠕變變形量逐漸增大;泊松比小于0.25時,井壁煤巖蠕變變形不明顯,而后隨著泊松比的增大,井壁煤巖蠕變變形顯著增大;隨著井徑的增大,井壁煤巖蠕變逐漸呈現(xiàn)非線性增大;隨著最大水平地應(yīng)力的增加,煤層氣井壁煤巖蠕變變形逐漸增大。本文所提出的煤巖蠕變力學(xué)模型,建立的煤層氣井壁煤巖蠕變規(guī)律數(shù)值模擬方法,有助于認(rèn)識煤巖蠕變造成煤層氣井壁失穩(wěn)機(jī)制,同時對于煤層氣開采安全鉆井和有效開展完井與固井施工等均具有重要的實(shí)際意義。
[Abstract]:Coal bed gas is a kind of clean energy, China has rich coal bed gas reserves. The exploitation and utilization of coal bed gas resources can not only effectively contain coal mine gas disaster, reduce the greenhouse effect of methane gas to the atmosphere environment, but also optimize the energy structure of China and alleviate the problem of energy shortage. However, because of the special mechanical properties of coal and rock and coal bed gas reservoir With the characteristics of complex geological environment, the problem of coalbed gas well wall stability seriously restricts the exploration and development of coal bed gas resources in China. In this paper, the phenomenon of coalbed gas well shrinkage, drilling and even wall collapse is particularly prominent because of coal and rock creep. This paper uses indoor petrophysics Li Xueshi test, creep model theory research and numerical simulation research, etc. Methods, the physical and mechanical properties of the coal rock and the Creep Mechanics Characteristics of the coal seam gas reservoir rock are systematically and deeply studied. The model of coal rock elastic viscoplastic creep and the creep model based on the energy angle are established. At the same time, the model is compared with the existing rock creep model, and the suitable model is optimized to describe the creep characteristics of the coal and rock. Finally, the COMSO is adopted. L numerical simulation software is used to analyze the creep law of coal bed gas well affected by the elastic modulus of coal and rock, the Poisson's ratio, the distribution of ground stress and the change of well diameter. The main conclusions are as follows: (1) the physical properties of coal and rock, such as dry density, natural density, water content, specific surface area, total pore volume, average pore size and so on, are obtained as follows. It is found that the total pore volume of coal and rock is related to specific surface area, and it is basically linear and positive correlation. (2) the uniaxial creep mechanical experiment of coal rock shows that when the axial stress increases from 0.98MPa to 5.98MPa, the creep process of coal sample is decaying creep, and when the axial stress is 6.49MPa, the creep process of coal sample is non attenuated creep, coal rock. The long-term strength is between 5.98~6.49MPa. (3) according to the experimental results of Coal Rock Creep Mechanics, the western original model has been improved, and the Creep Mechanics Model Based on the viscoelastic properties of coal and rock is obtained, and the constitutive equation and the creep equation are derived. The improved western original model can reflect the two exponential attenuation characteristics of the creep curve of the coal rock. (4) At the energy point of view, a creep mechanical model of coal and rock is proposed. The model is based on the West original model with a winding delta element, which is characterized by the T3 relationship between strain and time under the stress condition. The constitutive equation and the creep equation of the Coal Rock Creep Mechanics Model Based on the energy angle are derived. (5) coal seam gas reservoir wall coal. The maximum creep deformation direction of the rock is the maximum horizontal stress direction, and the borehole deformation presents the maximum main stress direction and produces the large shrinkage diameter. With the decrease of the modulus of elasticity, the creep deformation of coal bed coal rock increases gradually. When the Poisson's ratio is less than 0.25, the creep deformation of the coal rock is not obvious, and then with Poisson's ratio The creep deformation of coal and rock increases significantly, with the increase of the diameter of the well, the creep of the coal and rock gradually increases, and with the increase of the maximum horizontal stress, the creep deformation of the coal bed coal rock increases gradually. It is helpful to understand the mechanism of coalbed methane well wall instability caused by the creep of coal and rock, and it is of great practical significance for the safe drilling of coal bed gas exploitation and the effective completion and cementing construction.

【學(xué)位授予單位】：西南石油大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TD842

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 岳世權(quán),李振華,張光耀;煤巖蠕變特性試驗(yàn)研究[J];河南理工大學(xué)學(xué)報(bào)(自然科學(xué)版);2005年04期

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本文編號：1799506