【作者】 岳欠杯；

【导师】 刘巨保； 罗敏；

【作者基本信息】 大庆石油学院 ， 工程力学， 2009， 硕士

【摘要】 压裂作业是改进油气层渗透率、提高油气井产量的有效途径之一,压裂管柱设计和施工参数优选的主要依据是压裂管柱受力变形分析。本文针对深井笼统压裂和分次压裂管柱、水平井双卡压裂管柱的结构,选取整体压裂管柱为研究对象,考虑了水力锚、封隔器、滑套喷砂器在下井、坐封、压裂工况下的受力状态和位移边界,建立了压裂管柱非线性力学分析模型。采用间隙元模拟压裂管柱与套管内壁接触摩擦状态,推导出轴向摩阻力与位移协调条件,统一描述水力锚、封隔器、滑套喷砂器在不同工况下的受力和变形状态,建立了压裂管柱双重非线性有限单元法。采用delphi语言开发了“压裂管柱受力变形分析”软件,可计算管柱在不同排量、压力、卡距等条件下管柱的变形、内力和应力,以及水力锚、封隔器、滑套喷砂器的受力状态和轴向位移。通过实例计算可得出,在深井3800m笼统压裂管柱中,当压裂压力由60MPa增加到80MPa时,水力摩阻由9.81MPa/1000m变为15.87MPa/1000m,井口轴力由826.85kN变为1046.85kN,水力锚锚定力由129.28kN增加至336.31kN,最大等效应力由507.68MPa变为655.33MPa。在水平井2087m双卡压裂管柱中,当压裂压力为50MPa时,上封隔器的轴向位移相对于坐封工况向下窜动的最大距离为0.19mm,在卡距为10m、20m、30m时,下封隔器的轴向位移分别为11.17mm、23.78mm、36.46mm。在深井3800m分次压裂管柱中,当管柱上提0.2m时,在一次压裂作业中,滑套喷砂器由于坐封压力相对于下井位置向上滑动了2.89mm,在压裂工况中相对于坐封位置向上滑动了1.21mm;在二次压裂作业中,滑套喷砂器由于坐封压力相对于下井位置向下滑动了171.39mm,在压裂工况中相对于坐封位置向下滑动了4.64mm;管柱提升距离只要大于176mm时,滑套喷砂器与固定封隔器在两种压裂作业下均没有发生接触,为了保证固定封隔器在压裂作业中安全工作,推荐下井时将管柱上提0.2m距离。经现场试验井表明,根据计算出的轴向位移能准确控制压裂位置,设计出的压裂管柱能满足工艺要求和强度条件,验证了理论方法的正确性和软件的实用性。为了进一步描述压裂液温度和压力对管柱受力状态的影响,选取管内流动的压裂液、管柱外环空静止井液和压裂管柱为研究对象,建立了温度场、流场和应力场耦合分析的多物理场模型,计算得到1000m压裂管柱在井底处内壁温度36.99℃、外壁温度50.55℃,压裂液轴向压降0.83MPa,为压裂管柱力学分析中准确描述压裂液温度、压力作用提供了理论依据。更多还原

【Abstract】 Fracturing operation was one of the effective way to improve hydrocarbon reservoir’s permeability and raise oil and gas well’s production. The mechanical analysis was the basis of designing the fracturing string and optimizing the construction parameters. This article was in view of the configuration about vague, graded fracturing string in deep well and the fracturing string in horizontal well. The overall fracturing string was selected as research objects. The load conditions and displacement boundary of the packer, hydraulic anchor and sand blasting sleeve was considered in the descent down hole, setting and fracturing operational mode. The nonlinear mechanical model about fracturing string was established. The gap element was adopted to simulate the contact condition between the fracturing string and the inside wall of the casing. The conditions of compatibility between the axial friction and the axial displacement was derived out. The forces and deformation status of the hydraulic anchor, packer and sand blasting sleeve were unified described under different operational mode. The dual nonlinear finite element methods was established. The software about the“deformation analysis of fracturing string”was developed by delphi language. It could compute the fracturing string’s deformation, internal force and stress as well as the axial force displacement of the hydraulic anchor, packer and sand blasting sleeve under the different conditions of the displacement, pressure, card distance. In the vague fracturing string with well depth of 3800m, when the fracture pressure became form 60 MPa to 80 MPa, the hydraulic friction was form 9.81 MPa/1000m to 15.87 MPa/1000m, the axial force was form 826.85 kN to 1046.85 kN , the anchorage force was from 129.28 kN to 336.31 kN, the max equivalent stress became form 507.68 MPa to 655.33 MPa. In the horizontal dual grip fracturing string with the depth of 2087m, when the fracture pressure was 50 MPa, the axial displacement of the upper packer was 0.19 mm. For the card distance from the 10m to 30m at dual-card fracturing string, the axial displacement of the lower packer was respectively 11.17 mm, 23.78 mm, 36.46 mm. At graded fracturing string with the depth of 3800m,when lifting the string 0.2m, in primary fracturing, the sand blasting sleeve’s axial displacement was 2.89 mm in the setting operational mode, while in the fracturing operational mode, the value was 1.21 mm. In the after fracturing, the axial displacement was respective 171.39 mm,4.64 mm. If the lifting distance of the fracturing string was greater than 176 mm, there was no contact between the sand blasting sleeve and the fixed packer. In order to guarantee a fixed packer fracturing safe in operations,0.2m was recommend. The axial displacement could accurately predict the location of fracturing. Therefore,it verify the accuracy of the theoretical methods and the practicality of the software.In order to further describe the impact of the fluid temperature and pressure on the fracturing string, the flow fracturing fluid, the static fluid outside the tubular and the fracturing string was selected as objects. The coupling analysis model of the physical field with the temperature field, flow field and stress field was set up. The inner wall temperature was 36.99℃. Its outer wall temperature was 50.55℃. The axial pressure drop with the fracturing fluid was 0.83 MPa. It would provide a theoretical basis for accurately describing the fracturing fluid temperature and pressure.更多还原