【作者】 李茂华；

【导师】 徐守余；

【作者基本信息】 中国石油大学 ， 地质工程， 2008， 硕士

【摘要】 油田生产中套管可以保护井壁,分隔油气层,分层开采油层,并可以采用注水开发措施,保持油井正常生产。套管在生产中的变形损坏会影响油田的正常生产。油田生产中采用强化采油措施造成地层岩体运动地应力发生变化,套管的工作环境变化地层应力产生较大变化,地应力作用于套管造成套管变形损坏。油田生产中套管损坏主要发生在岩盐层段。地层蠕变,构造运动和生产层段的压裂酸化措施会造成大量套管损坏。随着油田开发,套管损坏影响了油田的经济效益。因此,研究套管损坏机理对提出有效的施工方案有重要理论意义。岩层在油井生产中,其孔隙压力发生变化,改变了地层的应力状态,岩层发生变形产生非均匀地应力挤压套管,造成套管应力增加变形损坏。油井生产中,非均匀地应力作用于套管,造成套管应力增加产生变形。套管在无水泥环作用下,力学性质和水泥环作用下的力学性质变化较大。建立套管的平面应变的有限元模型,计算分析套管在均匀载荷下的应力应变大小和套管在非均匀载荷下的应力大小和变形特征,可以较好的分析套管的力学性质,提出增加套管强度的理论方法。本文应用套管损坏机理,结合岩石力学理论,对套管损坏井受力分析,并且建立套管的力学模型。计算分析表明油井长期开采会造成地层应力发生较大变化,套管受到水泥环外壁地应力的挤压和轴向地层压力作用产生较大应力造成套管变形损坏。在分析套管力学模型的理论上,建立套管和套管水泥环组合的有限元平面和空间模型。应用水泥环套管有限元模型的计算结果,分析套管和套管水泥环组合在外压作用下应力应变大小,提出有效的套管损坏防治方案,提高套管的抗挤强度。更多还原

【Abstract】 The casing can protect borehole wall,separate the hydrocarbon reservoir,produce from separate zones,adopt flood development measure and maintain oil well production. The casing failure will affect the regular field production. The well stimulation can raise the production. That will bring about stratum rock mass to generate movement and make the crustal stress coming to alteration. The casing working environment that is alternate will bring about bigger altering to the the crustal stress. When the altering crustal stress acts on casing, it will cause the casing damage. The casing-failure chiefly occurs on the rock salt formation. That results from stratum creepage, tectonic movement, fracture acidizing meassures in producing,it will cause a great quantity of casing coming into regional breakdown. Along with the field development, casing failure affect the enonomy and productivity. Hence, studing the casing producing mechanism will propose better building measures to rasie the casing intensity.The pore pressure of rock formation will be alteration in the production and it will alter the stress condition of the formation. The rock formation will be deformed and compresses casing, it makes the stress of casing rising. The cement sheath has an important contribution to the casing mechanics property. Establishing the casing finite element model will have a good arithmetical solution to analyse the casing stress and deformation and it can propose the measures to enhance the casing collapsing strength.This article is according to casing failure mechanism and combines rock mechanics theory to analyse the casing stress. According to theory analysis, this theme will establish casing mechanical model. From computational analysis, the crustal stress varies a lot owing to a long producing term. The casing that affects by the cement sheath in the layer and be exerted by the crustal stress and axial formation pressure will become deformed. That causes casing failure and decrease casing collapsing strength.According to analysis of casing mechanical model theory to establish casing and casing-cement sheath finite element model that is in the plane and air space. From finite element model calculation, there will be analysis of deformation and stress-strain relationship of casing on which the external pressure be acted. Accoding to the analysis of casing finite element model calculation, it can be proposed to effective measures to enhance casing collapsing strength.更多还原