本文選題：熱力耦合　切入點(diǎn)：花崗巖鉆井　出處：《太原理工大學(xué)》2017年碩士論文

【摘要】：在深部能源開(kāi)發(fā)中,不論是傳統(tǒng)的油氣資源開(kāi)采,還是綠色的干熱巖地?zé)豳Y源的開(kāi)發(fā),首先需要解決的核心問(wèn)題就是高溫高應(yīng)力耦合作用下,深鉆施工及鉆井穩(wěn)定性控制問(wèn)題。深鉆施工過(guò)程中,由于較高地應(yīng)力及地溫的影響,鉆井穩(wěn)定性大幅降低,維護(hù)費(fèi)用增加,嚴(yán)重制約著深部能源的開(kāi)發(fā)。針對(duì)深鉆施工中遇到地層為花崗巖,在分析、總結(jié)課題組“高溫-高應(yīng)力下花崗巖鉆井圍巖力學(xué)實(shí)驗(yàn)”的基礎(chǔ)上,通過(guò)數(shù)值模擬方法,借助MATLAB及COMSOL Multiphysics5.2軟件,研究了熱力耦合作用下花崗巖鉆井圍巖熱彈性變形規(guī)律、熱力耦合作用下花崗巖鉆井圍巖蠕變破壞規(guī)律、分析了鉆孔破壞半徑與加載應(yīng)力及溫度之間的關(guān)系,最終得到熱力耦合作用下花崗巖鉆井圍巖失穩(wěn)破壞臨界條件。(1)分析課題組“高溫-高應(yīng)力下花崗巖鉆井圍巖力學(xué)實(shí)驗(yàn)”數(shù)據(jù),得到以下結(jié)論:1)熱力耦合作用下花崗巖鉆孔在不同溫度區(qū)間內(nèi),鉆孔熱應(yīng)變?cè)鲩L(zhǎng)趨勢(shì)不同;不同溫度下花崗巖鉆孔熱應(yīng)變隨埋深應(yīng)力的增大,其數(shù)值有降低的趨勢(shì)。2)熱力耦合作用下花崗巖鉆孔蠕變破壞失穩(wěn)存在較為顯著的閾值,即應(yīng)力閾值為4000米埋深應(yīng)力,溫度閾值為480℃。3)熱力耦合作用下鉆孔圍巖破壞特征具有顯著端部效應(yīng)、縮頸、鉆孔內(nèi)壁破壞;沿位移等值線存在較為顯著的錯(cuò)動(dòng)、滑移,有顯著的剪切破壞痕跡,最終圍繞鉆孔形成錐字形破壞面。4)高溫對(duì)花崗巖基本力學(xué)參數(shù)影響顯著,其基本力學(xué)參數(shù)彈性模量E、泊松比μ、熱膨脹系數(shù)α等均可看做是溫度的函數(shù)。(2)研究熱力耦合作用下花崗巖鉆井圍巖熱彈性變形規(guī)律,得到以下結(jié)論:1)試件在加溫過(guò)程中存在顯著的溫度梯度,且溫度梯度產(chǎn)生的熱應(yīng)力只在加熱過(guò)程中對(duì)鉆孔圍巖熱應(yīng)變產(chǎn)生影響;熱力耦合作用下花崗巖試件內(nèi)部主要受壓應(yīng)力作用,其最大值位于試件外側(cè),鉆孔內(nèi)壁壓應(yīng)力值較小;位移最大值位于試件外側(cè),最小值位于鉆孔內(nèi)壁。2)熱力耦合作用下花崗巖鉆孔熱彈性變形產(chǎn)生破壞的溫度閾值:3000米埋深應(yīng)力下的溫度閾值為210℃;4000米、5000米埋深應(yīng)力下的溫度閾值為195℃。3)在熱力耦合作用下花崗巖鉆孔熱彈性變形中,存在端部效應(yīng)且破壞沿著位移等值線產(chǎn)生顯著的滑移、錯(cuò)動(dòng),造成鉆孔內(nèi)壁附近發(fā)生流變破壞。(3)研究熱力耦合作用下花崗巖鉆井圍巖蠕變規(guī)律,得到以下結(jié)論:1)不同熱力耦合作用下花崗巖鉆孔圍巖流變位移規(guī)律一致,即鉆孔內(nèi)壁處流變位移最大,沿著鉆孔徑向方向,流變位移逐漸減小。2)在相同埋深應(yīng)力及加載溫度條件下,考慮蠕變效應(yīng)后,鉆孔圍巖的流變位移顯著增大,使得鉆孔圍巖產(chǎn)生破壞的閾值降低,即為:2000米埋深應(yīng)力溫度200℃,且相同條件下流變產(chǎn)生破壞區(qū)半徑遠(yuǎn)大于熱彈性變形時(shí)產(chǎn)生的破壞半徑。(4)熱力耦合作用下鉆井圍巖失穩(wěn)破壞臨界條件為σ=241.9-0.3998·T。
[Abstract]:In deep energy development, whether traditional oil and gas resources exploitation or green dry hot rock geothermal resources development, the first need to solve the core problem is the coupling of high temperature and high stress. Deep drilling and drilling stability control. During deep drilling, due to the influence of high ground stress and ground temperature, the drilling stability is greatly reduced and the maintenance cost is increased. The development of deep energy resources is seriously restricted. In view of the granite formation encountered in deep drilling construction, on the basis of analyzing and summarizing the "mechanics experiment of granite drilling surrounding rock under high temperature and high stress", the numerical simulation method is adopted. With the help of MATLAB and COMSOL Multiphysics5.2 software, the thermoelastic deformation law of surrounding rock in granite drilling under thermal coupling and creep failure law of surrounding rock in granite drilling under thermal coupling are studied. The relationship between borehole failure radius and loading stress and temperature is analyzed. Finally, the critical condition of failure failure of surrounding rock in granite drilling under thermal-mechanical coupling is obtained.) the data of "Mechanical experiment of surrounding Rock in Granite drilling under High temperature and High stress" are analyzed by our research group. The following conclusions are obtained: (1) the thermal strain growth trend of granite borehole is different in different temperature range, and the thermal strain of granite borehole increases with buried depth stress at different temperature. The numerical value has a decreasing tendency. 2) the creep failure instability of granite borehole under the coupling of heat and heat has a significant threshold, that is, the stress threshold is 4000 meters buried depth stress. When the temperature threshold is 480 鈩，

本文編號(hào)：1677157