本文選題：氣體鉆井 + 致密砂巖　； 參考：《西南石油大學(xué)》2015年碩士論文

【摘要】：氣體鉆井能夠有效的減小儲(chǔ)層損害并及時(shí)發(fā)現(xiàn)儲(chǔ)層,近幾年逐漸用于致密砂巖氣的勘探開(kāi)發(fā)。采用氣體鉆井打開(kāi)高壓致密砂巖儲(chǔ)層過(guò)程,出現(xiàn)一些不同于常規(guī)氣體鉆井的井眼垮塌現(xiàn)象。實(shí)鉆顯示高壓含氣致密砂巖儲(chǔ)層擴(kuò)徑嚴(yán)重,并多次誘發(fā)井下惡性垮塌埋鉆事故,嚴(yán)重制約了致密砂巖氣藏的勘探開(kāi)發(fā)。本文結(jié)合氣體鉆井打開(kāi)高壓含氣致密砂巖儲(chǔ)層現(xiàn)場(chǎng)工況,通過(guò)室內(nèi)巖石力學(xué)實(shí)驗(yàn)和應(yīng)力敏感性實(shí)驗(yàn),以滲流理論和彈塑性理論為基礎(chǔ),建立了氣體鉆井井周彈性應(yīng)力分布模型和彈塑性應(yīng)力分布模型,研究了致密砂巖儲(chǔ)層井眼擴(kuò)徑機(jī)理和影響因素,為氣體鉆井安全打開(kāi)高壓含氣致密砂巖儲(chǔ)層提供理論基礎(chǔ)。主要得到以下幾個(gè)結(jié)論： (1)分析了氣體鉆井鉆開(kāi)致密砂巖儲(chǔ)層的現(xiàn)場(chǎng)工況和地質(zhì)特征,表明高壓含氣致密砂巖儲(chǔ)層段氣體鉆井井眼擴(kuò)徑不同于常規(guī)氣體鉆井,在打開(kāi)儲(chǔ)層過(guò)程中,井周會(huì)形成剪切帶和壓實(shí)帶,井周巖石處于復(fù)雜應(yīng)力場(chǎng)中,從而導(dǎo)致致密砂巖儲(chǔ)層容易發(fā)生失穩(wěn)。 (2)通過(guò)致密砂巖力學(xué)實(shí)驗(yàn)研究了孔隙壓力、圍壓和軸向壓力對(duì)巖石力學(xué)參數(shù)的影響。致密砂巖孔隙含壓時(shí)的三軸抗壓強(qiáng)度大于不含壓時(shí)的抗壓強(qiáng)度,隨著孔隙壓力的增加,巖石抗壓強(qiáng)度減小。隨著有效圍壓的增加,巖石的彈性模量呈冪函數(shù)增長(zhǎng)。軸向加載速率越大,巖石殘余階段應(yīng)力下降速率越快,巖石越容易完全破碎。 (3)通過(guò)變圍壓和變孔隙壓力兩種不同的方法測(cè)試了致密砂巖的應(yīng)力敏感性。采用常規(guī)變圍壓應(yīng)力敏感性實(shí)驗(yàn)比變孔隙壓力應(yīng)力敏感性實(shí)驗(yàn)敏感,并且在常規(guī)變圍壓應(yīng)力敏感性實(shí)驗(yàn)過(guò)程中發(fā)現(xiàn),滲透率下降到一定程度后繼續(xù)增加有效圍壓,致密砂巖滲透率基本沒(méi)有變化。 (4)基于常規(guī)氣體鉆井井周彈性應(yīng)力分布模型,綜合考慮孔隙壓力、彈性模量非線性和井眼形狀,分析了氣體鉆井井周應(yīng)力變化規(guī)律。當(dāng)采用氣體鉆井的方式打開(kāi)致密砂巖儲(chǔ)層后由于孔隙壓力的變化導(dǎo)致井眼周圍巖石的應(yīng)力場(chǎng)發(fā)生變化,井眼附近地層滲透率降低,形成一個(gè)壓實(shí)帶,阻止地層中氣體向井眼中滲流。隨著井眼垮塌,由于應(yīng)力集中,井眼進(jìn)一步向地層中發(fā)展,但是由于巖石殘余強(qiáng)度的影響,井眼最終會(huì)穩(wěn)定。 (5)利用氣體鉆井井周彈塑性應(yīng)力分布模型研究了井眼垮塌后地層中穩(wěn)定滲流和沒(méi)有滲流情況下井周彈塑性區(qū)分布和影響因素。研究結(jié)果表明：當(dāng)巖石內(nèi)聚力和內(nèi)摩擦角角減小時(shí),井周塑性區(qū)域增加,井眼容易發(fā)生垮塌失穩(wěn)；當(dāng)氣體滲流量增加時(shí),井周塑性區(qū)域會(huì)增加。
[Abstract]:Gas drilling can effectively reduce reservoir damage and timely discovery of reservoir, in recent years gradually used in the exploration and development of tight sandstone gas. When gas drilling is used to open high pressure tight sandstone reservoir, there are some hole collapses which are different from conventional gas drilling. The actual drilling shows that the high pressure gas-bearing tight sandstone reservoir has serious dilatation and many times induces the downhole malignant collapse and burying drilling accident, which seriously restricts the exploration and development of the tight sandstone gas reservoir. In this paper, based on seepage theory and elastic-plastic theory, combined with gas drilling to open high pressure gas-bearing tight sandstone reservoir, through laboratory rock mechanics experiment and stress sensitivity experiment, The elastic stress distribution model and elastic-plastic stress distribution model around gas drilling wells are established. The hole expansion mechanism and influencing factors in tight sandstone reservoirs are studied, which provides a theoretical basis for the safe opening of high-pressure gas-bearing tight sandstone reservoirs in gas drilling. The main conclusions are as follows: 1) the field working conditions and geological characteristics of tight sandstone reservoir drilled by gas drilling are analyzed. The results show that the hole expansion of gas drilling in high pressure gas-bearing tight sandstone reservoir is different from that in conventional gas drilling, and in the process of opening the reservoir, The shear zone and compaction zone are formed around the well, and the rock around the well is in the complex stress field, which leads to the instability of tight sandstone reservoir. 2) the effects of pore pressure, confining pressure and axial pressure on the mechanical parameters of rock are studied by means of the mechanical experiments of tight sandstone. The triaxial compressive strength of tight sandstone with pore pressure is greater than that without pore pressure, and the compressive strength of rock decreases with the increase of pore pressure. With the increase of effective confining pressure, the elastic modulus of rock increases by power function. The higher the axial loading rate is, the faster the stress decreases in the residual stage of rock, and the easier the rock is completely broken. 3) stress sensitivity of tight sandstone was tested by two different methods: variable confining pressure and variable pore pressure. The conventional stress sensitivity test of varying confining pressure is more sensitive than that of the stress sensitivity experiment of varying pore pressure, and it is found that the permeability decreases to a certain extent and the effective confining pressure continues to increase. The permeability of tight sandstone is basically unchanged. 4) based on the elastic stress distribution model of conventional gas drilling wells, the variation of borehole stress in gas drilling is analyzed by considering the pore pressure, elastic modulus nonlinearity and borehole shape. When the tight sandstone reservoir is opened by gas drilling, the stress field of the rock around the borehole changes due to the change of pore pressure, and the formation permeability near the borehole decreases, forming a compaction zone. Prevent gas in the formation from percolating to the hole. As the borehole collapses, the borehole develops further into the formation due to stress concentration, but due to the influence of rock residual strength, the borehole will eventually be stable. (5) the elastic-plastic stress distribution model around the borehole in gas drilling is used to study the distribution of elastic-plastic zone and the influencing factors in the condition of stable percolation and no percolation in the formation after hole collapse. The results show that when the cohesive force and angle of friction decrease, the plastic region around the well increases and the hole collapses easily, and the plastic region increases when the gas flow rate increases.
【學(xué)位授予單位】：西南石油大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TE24

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