本文選題：井下水力壓裂 + 應(yīng)力場��； 參考：《中國礦業(yè)大學(xué)》2013年博士論文

【摘要】：論文針對井下煤層水力壓裂過程中濾失率引起的煤體水分增加對瓦斯運(yùn)移的負(fù)效應(yīng)以及“瓦斯場、滲流場、應(yīng)力場”重新分布規(guī)律問題，采用理論分析、數(shù)值模擬、實(shí)驗(yàn)室實(shí)驗(yàn)和現(xiàn)場工業(yè)性試驗(yàn)相結(jié)合的方法，分析了不同煤體結(jié)構(gòu)適應(yīng)性的井下水力壓裂技術(shù)，研究了煤-水-氣三相介質(zhì)條件下瓦斯解吸規(guī)律，揭示了水力壓裂影響區(qū)域地應(yīng)力分布特征，探討了水力壓裂煤層瓦斯運(yùn)移產(chǎn)出的雙重效應(yīng)，指出了利用瞬變電磁法和示蹤劑法對井下煤層水力壓裂流場分布特征研究和評價(jià)的可行性。 （1）煤-水-氣三相介質(zhì)條件下瓦斯解吸規(guī)律的實(shí)驗(yàn)/試驗(yàn)研究表明，煤樣含水率越高，累計(jì)解吸量越少、瓦斯解吸速率越低；ΔP、q、K13個(gè)指標(biāo)值隨煤體含水率的增大而減小。說明水分對瓦斯解吸運(yùn)移不但有抑制作用，同時(shí)還揭示出含水狀態(tài)下所測試的校檢指標(biāo)，掩蓋了煤與瓦斯突出危險(xiǎn)性。 （2）井下單孔水力壓裂數(shù)值模擬表明，壓裂孔兩側(cè)本來的應(yīng)力升高區(qū)域地應(yīng)力大大降低，很大范圍內(nèi)地應(yīng)力都降低到低狀體，鉆孔兩側(cè)及Z方向煤體發(fā)生位移；現(xiàn)場水力壓裂影響區(qū)鉆屑量的變化特征，反映了壓裂后集中應(yīng)力帶向煤體深部轉(zhuǎn)移，采掘工作面卸壓帶長度增大，鉆屑量變化響應(yīng)的工作面應(yīng)力分布狀態(tài)，與壓裂影響區(qū)應(yīng)力場特征數(shù)值模擬結(jié)果一致；通過數(shù)值模擬同時(shí)也發(fā)現(xiàn)了水力壓裂的不足之處，，在裂縫尖端也產(chǎn)生了新的應(yīng)力集中。 （3）針對煤層賦存地質(zhì)條件的復(fù)雜性和非均質(zhì)性，以及水力壓裂研究過程中出現(xiàn)的壓裂液流場短路、裂隙擴(kuò)展分布不均、單孔尖端應(yīng)力集中等現(xiàn)象，提出了“雙孔（多孔）均勻壓裂、定向鉆進(jìn)控制壓裂、水力噴射輔助壓裂、預(yù)先水力割縫導(dǎo)向壓裂、開楔形環(huán)槽定向壓裂”5種用于實(shí)現(xiàn)煤層整體、均勻壓裂的優(yōu)化工藝。 （4）利用流態(tài)判識標(biāo)準(zhǔn)雷諾數(shù)Re和啟動壓力梯度λ，對水力壓裂增透加速瓦斯產(chǎn)出的正效應(yīng)，以及煤體水分增大抑制瓦斯運(yùn)移負(fù)效應(yīng)的研究表明，含水率并不是影響啟動壓力梯度的主要因素，當(dāng)煤層滲透率增大到一定程度，啟動壓力梯度就將消失，揭示了對于透氣性較好的高滲煤層，水分的增加對瓦斯抽采的影響是有限的，水力壓裂增透加速瓦斯抽采的本質(zhì)是改變了瓦斯在煤層內(nèi)流態(tài)，與壓裂過程中壓裂液濾失引起的負(fù)效應(yīng)相比，壓裂增透產(chǎn)生的正效應(yīng)對瓦斯運(yùn)移產(chǎn)出起控制作用。 （5）針對在評價(jià)壓裂流場分布特征（滲流能力、影響范圍、均勻程度）方面存在的難題，構(gòu)建了含瓦斯煤體水力壓裂流場評價(jià)數(shù)學(xué)模型，開展了基于瞬變電磁法和示蹤劑跟蹤法的水力壓裂流場分布特征理論和實(shí)驗(yàn)研究，豐富了井下水力壓裂評價(jià)的方法和手段，對提高現(xiàn)場施工質(zhì)量、減小施工風(fēng)險(xiǎn)有很大應(yīng)用價(jià)值。
[Abstract]:Aiming at the negative effect of the increase of coal body moisture on gas migration and the redistribution of gas field, seepage field and stress field in the process of hydraulic fracturing in underground coal seam, theoretical analysis and numerical simulation are used in this paper. Combining the laboratory experiment with the field industrial test, the underground hydraulic fracturing technology with different coal structure adaptability is analyzed, and the gas desorption law under the condition of coal-water-gas three-phase medium is studied. The distribution characteristics of in-situ stress in the area affected by hydraulic fracturing are revealed, and the dual effect of gas migration and production in hydraulic fracturing coal seam is discussed. The feasibility of using transient electromagnetic method and tracer method to study and evaluate the distribution characteristics of hydraulic fracturing flow field in underground coal seam is pointed out. (1) the experimental and experimental study on the law of gas desorption under the condition of coal-water-gas three-phase medium shows that; The higher the moisture content of coal sample is, the less the cumulative desorption amount is, and the lower the gas desorption rate is; The results show that water can not only restrain the gas desorption migration, but also reveal the check index of the gas desorption and migration under the condition of water content, and cover up the danger of coal and gas outburst. (2) the numerical simulation of hydraulic fracturing in single hole shows that The in-situ stress on both sides of the fracturing hole has been greatly reduced, the in-situ stress has been reduced to a low body in a wide range, the displacement occurred on both sides of the borehole and the Z direction coal body, and the variation characteristics of the cuttings amount in the affected area of hydraulic fracturing, The results show that the stress distribution state of the coal face after fracturing is the same as the numerical simulation results of stress field characteristics in the area affected by fracturing, where the length of pressure relief zone increases and the response of cuttings quantity changes after fracturing. At the same time, the shortage of hydraulic fracturing is found by numerical simulation, and a new stress concentration is also produced at the fracture tip. (3) aiming at the complexity and heterogeneity of the geological conditions of coal seam occurrence, As well as the phenomena such as short circuit of fracturing fluid flow field, uneven distribution of fracture propagation, stress concentration at the tip of single hole and so on in the process of hydraulic fracturing, it is proposed that "double hole (porous) uniform fracturing, directional drilling control fracturing, hydraulic jet assisted fracturing, etc." In advance hydraulic fracturing and directional fracturing with wedge ring groove "5 kinds of fracturing are used to realize the whole of coal seam." Optimization technology of uniform fracturing. (4) by using Reynolds number and starting pressure gradient 位, the positive effect of hydraulic fracturing on accelerating gas production and the negative effect of increasing coal moisture on gas migration are studied. Water cut is not the main factor affecting the starting pressure gradient. When the permeability of coal bed increases to a certain extent, the starting pressure gradient will disappear. The effect of water increase on gas drainage is limited. The essence of hydraulic fracturing and accelerating gas drainage is to change the gas flow state in coal seam, compared with the negative effect caused by fracturing fluid filtration during fracturing. The positive effect of anti-permeability fracturing plays a controlling role in gas migration and production. (5) in order to evaluate the distribution characteristics of fracturing flow field (seepage ability, influence range, uniformity), The mathematical model of flow field evaluation for gas-bearing coal body hydraulic fracturing is established, and the theory and experimental research on the distribution characteristics of hydraulic fracturing flow field based on transient electromagnetic method and tracer tracking method are carried out, which enriches the methods and means of underground hydraulic fracturing evaluation. It has great application value to improve the construction quality and reduce the construction risk.
【學(xué)位授予單位】：中國礦業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2013
【分類號】：TD825;TD712

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