井下工况及载荷对水泥环的影响研究

【作者】 李国；

【导师】 郭小阳；

【作者基本信息】 西南石油大学 ， 油气井工程， 2006， 硕士

【摘要】 在油气井建井及生产使用过程中，套管与水泥环共同承受外部载荷，其中任何一方的损坏都将对另一方乃至整个油气井的使用寿命产生严重影响，所以不能单方面考虑如何维护套管或者水泥环的完整性，必须从保护套管与水泥环整体完整性的角度进行研究。套管与水泥环的损坏是一个复杂过程，从钻井到开发以及后期增产都将对其产生影响。近年来，国内外学者围绕套管损坏问题展开了广泛和深入的研究，在套管损坏机理问题上取得了深刻的认识，然而在研究水泥环各项力学与几何参数的合理设计上，主要是考虑如何使设计的水泥环力学与几何参数对保护套管更加有利，其忽略了维护水泥环本身完整性的重要作用。为此，本文在对水泥环整个使用过程所经历的工况和承受的载荷进行分析的基础上，通过调整施工工艺和合理设计水泥环的各项力学与几何参数来达到维护层间封隔完整性的目的，具体内容如下： (1) 通过对水泥环整个使用过程的详细分析并结合目前水泥环设计方法得出：套管试压过程中引起的载荷与注水、酸化压裂等原因引起的非均匀地应力都可能导致水泥环的损坏，但目前的设计方法中又未全面考虑上述因素。 (2) 利用弹性力学的相关理论结合套管试压工艺建立套管与水泥环弹性耦合力学模型，得出套管与水泥环的应力、应变弹性解并编写计算程序。 (3) 利用计算程序详细分析了现行套管试压方法中水泥环的受力情况并得出，目前采用的套管试压方法完全可能导致水泥环损坏。 (4) 由于目前采用的套管试压方法完全可能导致水泥环损坏，所以本文在对现行套管试压方法详细分析的基础上提出了新的套管柱试压方法，以达到保护水泥环完整性和更好的检验套管密封性能的双重目的。 (5) 利用弹性力学的相关理论建立非均匀地应力作用下的套管、水泥环及地层的弹性耦合力学模型，得出套管与水泥环的应力、应变弹性解并编写计算程序。 (6) 利用计算程序分析非均匀地应力作用下，水泥环各力学与几何参数对套管与水泥环受力情况的影响。 (7) 结合目前套管柱设计思路，提出考虑非均匀载荷的设计方法和怎样在套管柱设计的基础上完善水泥环设计的综合设计方法。 (8) 编写水泥环参数设计软件，利用该软件可对套管与水泥环受力情况受水泥环各力学与几何参数影响情况进行分析，以达到更方便和更合理设计水泥环各力学与几何参数的目的。更多还原

【Abstract】 In the process of building the hole and production, casing and cement mantle withstand the loadings together, any one is damaged, it would shorten the using time of the other one and the oil well, so we couldn’t consider the integrity of one, and should do the reaserch of keeping the whole of casingcement mantle integrity. Faliure process of the casing_cement mantle is very complicate. Technique and practice used in drilling, producting and development programe all affect it. In recent years, many scholars have studied the causes and mechanism of the casing failure and many mechanisms of casing failure were recongnized, but when study how to design the parameters of the cement mantle, how to protect the casing is mostly considered and ignore the important function of keeping the cement mantle integrity. Hence, at the basis of doing reaserch of the stress and the working condition for the whole using process, we can keep hermetization by improving the technics and design the parameters in reason. The idiograhic contents as follow:(l)At the foundation of doing reaserch for the whole using process of the cement mantle and combine the designing methods, we can get the stress of the pressure test and the nonuniform formation loadings because of the water injection and the acid fracturing may lead the cement mantle to fail, but it haven’t considered all of the conditions now.(2)Based and explained casing and cement bond elasticity coupling mechanical moldels by using the theory of the elasticity mechanics and combine the pressure test technics, and workout correlative programme.(3)Analyse the stress of the cement mantle when doing casing pressure test, and gotten out that it may lead the cement mantle to failure.(4)Because the methods of the casing pressure test may lead the cement mantle to fail, this artice haven gotten out new methods of the casing pressure test based on the anlysis of the present methods of casing pressure test to achieve the aim of protecting the cement mantle and test the leak tightness of the casing.(5)Based and explained formation, cement bond and casing elasticity coupling mechanical models under non-uniform formation stress by using the theory of the elasticity mechanics, and workout correlative programme.(6) Analysing the stress of the casing_cement mantle which were affected by the parameters of the cement.(7)Bring forward a new method of casing design which will consider the non_uniform loadings combine the present method of the casing design, and bring forward how to design the cement mantle perfectly based on the method of the casing design.(8)Design software of cement parameters is programmed, by it we can analyse the stress更多还原