發(fā)布時(shí)間：2018-01-20 23:22

  本文關(guān)鍵詞： 水泥環(huán)缺陷 承載能力 仿真模擬 外擠力 Von Mises等效應(yīng)力　出處：《西南石油大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：水泥環(huán)缺陷會(huì)直接影響到套管的受力狀態(tài),并且往往會(huì)造成套管出現(xiàn)應(yīng)力集中現(xiàn)象,嚴(yán)重時(shí)甚至?xí)䦟?dǎo)致套管損壞。然而,目前國(guó)內(nèi)外針對(duì)水泥環(huán)缺陷對(duì)套管承載能力影響的相關(guān)研究還比較少,并且所建立的水泥環(huán)缺陷模型比較單一理想化,與實(shí)際并不十分相符。為此,本文首先在彈塑性力學(xué)的基礎(chǔ)上,建立了水泥環(huán)完好且受均勻地應(yīng)力作用的套管最大等效應(yīng)力計(jì)算模型；然后根據(jù)現(xiàn)場(chǎng)資料與室內(nèi)實(shí)驗(yàn)數(shù)據(jù),建立了不同類型的水泥環(huán)缺陷模型；最后利用有限元軟件對(duì)不同水泥環(huán)缺陷時(shí)的套管等效應(yīng)力進(jìn)行了模擬研究,得出水泥環(huán)缺陷對(duì)套管承載能力的影響規(guī)律。取得了如下主要認(rèn)識(shí)： (1)偏心環(huán)空水泥環(huán)缺失往往出現(xiàn)在環(huán)空窄間隙處,并且套管承載能力會(huì)隨著缺失面積的增加先急劇降低再迅速回升,并且回升幅度逐漸降低,最終接近但低于水泥環(huán)完好時(shí)的套管承載能力； (2)氣侵通道面積越大、通道位置離套管壁越近,套管的承載能力越低；氣侵通道對(duì)稱分布時(shí),通道數(shù)量越少,套管承載能力也會(huì)越低；當(dāng)存在兩條氣侵通道時(shí),兩通道相隔越遠(yuǎn),套管承載能力越低。當(dāng)套管偏心時(shí),氣侵通道位置離環(huán)空窄間隙越近,套管承載能力也會(huì)越低,并且此時(shí)氣侵通道數(shù)量對(duì)套管承載能力幾乎無(wú)任何影響； (3)微環(huán)隙缺失寬度的增加,雖然可以提高套管的承載能力,但同時(shí)會(huì)降低水泥環(huán)密封性,影響固井質(zhì)量,甚至導(dǎo)致一系列嚴(yán)重后果；當(dāng)微環(huán)隙不為完整圓形時(shí),隨著微環(huán)隙缺失長(zhǎng)度的增加,套管承載能力會(huì)急劇降低再逐漸緩慢回升,根據(jù)微環(huán)隙位置與寬度的不同,套管承載能力的降低與上升幅度也會(huì)不同； (4)水泥環(huán)的半月形缺失對(duì)套管承載能力的影響與氣侵通道的影響規(guī)律類似,但相同缺失程度情況下,半月形缺失導(dǎo)致的套管承載能力降低幅度更大； (5)套管承載能力隨著水泥石彈性模量的增加而快速降低接著再緩慢回升,隨著水泥石泊松比的增加而降低,但降幅很小,幾乎可以忽略不計(jì)。 通過(guò)本文的研究,為進(jìn)一步深入認(rèn)識(shí)水泥環(huán)缺陷對(duì)套管承載能力影響奠定了良好的基礎(chǔ)。
[Abstract]:Cement sheath defects will directly affect the stress state of the casing, and often lead to casing stress concentration phenomenon, and even lead to casing damage. At present, there are few researches on the influence of cement sheath defect on casing bearing capacity, and the cement ring defect model is single and idealized, which is not very consistent with the actual situation. On the basis of elastoplastic mechanics, a model for calculating the maximum equivalent stress of casing with intact cement sheath and subjected to uniform in-situ stress is established in this paper. Then, according to the field data and laboratory data, different types of cement ring defect models are established. Finally, the equivalent stress of casing with different cement sheath defects is simulated by using finite element software, and the influence of cement sheath defect on casing bearing capacity is obtained. The main results are as follows: 1) the loss of eccentric annulus cement ring often appears in the narrow gap of annulus, and the bearing capacity of casing decreases sharply with the increase of missing area, and then increases rapidly, and the range of recovery decreases gradually. The bearing capacity of casing is close to but lower than that of cement sheath. 2) the larger the area of the gas invasion channel, the closer the location of the passage from the sleeve wall, the lower the bearing capacity of the casing; When the gas invasion channel is distributed symmetrically, the smaller the number of channels, the lower the bearing capacity of casing. When there are two gas invasion channels, the longer the two channels are separated, the lower the casing bearing capacity is, and when the casing is eccentric, the closer the gas invasion channel is to the narrow gap between annulus and annulus, the lower the casing bearing capacity will be. At this time, the number of gas invasion channels has little effect on the bearing capacity of casing. 3) the increase of the missing width of microannulus can improve the bearing capacity of casing, but at the same time, it will reduce the sealing ability of cement ring, affect the cementing quality, and even lead to a series of serious consequences. When the microannular gap is not round, with the increase of the missing length of the microannular gap, the bearing capacity of the casing decreases sharply and then rises slowly, according to the difference of the position and width of the microannular gap. The decrease of bearing capacity of casing is different from that of rising. (4) the influence of semilunar loss of cement sheath on casing bearing capacity is similar to that of gas invasion channel. The bearing capacity of casing decreases rapidly with the increase of elastic modulus of cement stone and then rises slowly, and decreases with the increase of the ratio of cement stone to stone, but the decrease is very small and can be ignored. The research in this paper lays a good foundation for further understanding the influence of cement sheath defects on casing bearing capacity.
【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)】：TE256

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本文編號(hào)：1449739