本文選題：大斜度井段 + 紊流��； 參考：《東北石油大學(xué)》2015年碩士論文

【摘要】：水平井、大位移井在海洋油田、老油田和低滲透油田開發(fā)中得到了廣泛應(yīng)用。但在鉆井過程中,當(dāng)液流速度小于巖屑懸浮運(yùn)移速度時,巖屑容易在大斜度井段沉降并形成巖屑床,導(dǎo)致鉆柱高摩阻和扭矩、低機(jī)械鉆速、卡鉆等問題。因此,本文重點研究了大斜度井段偏心環(huán)空鉆井液紊流流動、巖屑起動以及鉆井液紊流攜巖規(guī)律,其預(yù)測值與實驗數(shù)據(jù)進(jìn)行了對比,驗證了模型的可靠性。采用結(jié)構(gòu)網(wǎng)格劃分環(huán)空流體域,用滑移網(wǎng)格模擬鉆柱旋轉(zhuǎn),基于Realizable k-ε紊流模型和SIMPLE求解方法,模擬了水平井段同心、偏心和存在靜止巖屑床的偏心環(huán)空鉆井液紊流特性。引入4種環(huán)空當(dāng)量直徑計算方法,通過與實驗數(shù)據(jù)對比發(fā)現(xiàn),選擇Slot或Lamb方法更能準(zhǔn)確預(yù)測環(huán)空摩擦壓降�？紤]巖屑床面顆粒的浮重、上舉力、拖拽力、液流壓耗、粘著力及附加質(zhì)量力,結(jié)合顆粒的隨機(jī)分布函數(shù)和紊流壁面律理論,建立巖屑滑移、滾動和舉升起動的力學(xué)模型。模型計算結(jié)果顯示,巖屑舉升起動所需鉆井液排量要高于滾動,且都隨巖屑床高度增大而減小,并據(jù)此估算巖屑床高度�；跉W拉固液兩相流模型和鉆井液Realizable k-ε紊流模型,模擬了偏心環(huán)空鉆柱旋轉(zhuǎn)條件下的鉆井液紊流攜巖規(guī)律。模擬發(fā)現(xiàn)鉆柱旋轉(zhuǎn)使得巖屑床沿旋轉(zhuǎn)方向傾斜,在環(huán)空內(nèi)呈非對稱分布狀態(tài),并減小環(huán)空巖屑濃度和固液壓降,其變化幅度受井斜角、巖屑注入濃度、巖屑直徑、鉆井液流速和粘度的影響,但當(dāng)轉(zhuǎn)速達(dá)到臨界值后,其作用效果并不顯著。根據(jù)數(shù)值模擬結(jié)果形成了巖屑體積濃度和固液壓降經(jīng)驗?zāi)Ｐ汀?br/>[Abstract]:Horizontal wells and long-reach wells have been widely used in the development of offshore oil fields, old oil fields and low permeability oil fields. However, in the drilling process, when the liquid flow velocity is less than the cuttings suspended migration velocity, the cuttings are easy to settle in the large slope well section and form cuttings bed, which leads to the problems of high friction and torque of drill string, low mechanical drilling speed, and drilling jam and so on. Therefore, in this paper, the turbulent flow of eccentric annulus drilling fluid, cuttings starting and turbulent rock carrying of drilling fluid are studied. The predicted values are compared with the experimental data, and the reliability of the model is verified. The structural grid is used to divide the annulus fluid domain, and the slip mesh is used to simulate the rotation of drilling string. Based on Realizable k- 蔚 turbulence model and SIMPLE solution method, the turbulent characteristics of eccentric annulus drilling fluid in horizontal well section with concentric, eccentricity and static cuttings bed are simulated. Four methods for calculating equivalent diameter of annulus are introduced. By comparing with experimental data, it is found that Slot or Lamb method can accurately predict friction pressure drop in annulus. Considering the floating weight, upward lifting force, towing force, fluid pressure consumption, adhesion force and additional mass force of debris bed particles, combined with the random distribution function of particles and the turbulent wall law theory, a mechanical model of cuttings sliding, rolling and lifting start is established. The model results show that the amount of drilling fluid required for cuttings lifting and starting is higher than that for rolling, and both of them decrease with the height of cuttings bed increasing, and the height of cuttings bed is estimated accordingly. Based on the Euler solid-liquid two-phase flow model and the Realizable k- 蔚 turbulence model of drilling fluid, the turbulent rock carrying law of drilling fluid under the condition of eccentric annulus drilling string rotation is simulated. The simulation results show that the drilling string rotation causes the cuttings bed to incline along the rotating direction, and presents an asymmetrical distribution state in the annulus, and reduces the sawdust concentration and the solid-liquid pressure drop in the annulus. The variation amplitude is affected by the angle of the well, the cuttings injection concentration and the cuttings diameter. The effect of velocity and viscosity of drilling fluid is not significant when the speed of drilling fluid reaches the critical value. Based on the numerical simulation results, an empirical model of cuttings volume concentration and solid-liquid pressure drop is established.
【學(xué)位授予單位】：東北石油大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TE254

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 汪志明,張政;水平井兩層穩(wěn)定巖屑傳輸規(guī)律研究[J];石油大學(xué)學(xué)報(自然科學(xué)版);2004年04期

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本文編號：1838026