考虑弱面影响的井壁稳定模型及其应用研究

发布时间：2018-08-13 13:49

【摘要】：有关井壁稳定性的研究一直是钻井工程关注的重点,由井壁失稳造成的一系列工程事故危害极大。由于井孔失稳破坏的情况多发生于地质条件复杂、层理裂隙广泛发育的软弱地层中,在井壁稳定模型分析中综合考虑地质软弱面的影响是有必要的。本文基于应力坐标转换关系及弱面-岩体的双强度准则,建立了含地质弱面地层的井壁稳定半解析计算模型,为充分理解地质弱面产状及各地层参数对井壁稳定性的影响提供理论依据,可有效指导安全钻井施工。此外,本文对于复杂地层中反演地应力的方法进行了一些探索。本文中开展的工作主要有:1、取含不同产状软弱结构面的岩样进行室内单轴压缩及超声波试验,以验证含弱面岩石的强度弱化特征,为随后理论分析提供实验依据;2、介绍了由测井资料获取地层参数数据的一般性方法,包括得到岩体物理、力学基本参数的一般公式,阐述了井壁稳定模型中输入地层参数的获取方法;3、建立了含地质弱面地层的井壁稳定模型,利用编程软件获得求解程序,验证求解程序的可靠性,对比了不同强度准则对计算结果的影响;4、考虑地应力水平的一般性和岩体中软弱结构面对井壁围岩强度的影响,对具体工况下的水平井、斜井稳定性进行计算,综合分析了影响井壁稳定性的因素,为复杂工况下合理施工提供指导性建议;5、探索利用所建模型在复杂地层中进行地应力反演工作的方法,由于目前钻孔崩落法反演地应力只适用于各向同性地层,该方法可作为其有效补充,以提供更加丰富的地应力反演资料。
[Abstract]:The research on wellbore stability has been the focus of drilling engineering, and a series of engineering accidents caused by wellbore instability are very harmful. Due to the fact that the failure of borehole instability occurs in the soft formation with complex geological conditions and widely developed bedding fractures, it is necessary to consider the influence of geological weak surface in the analysis of wellbore stability model. Based on the transformation of stress coordinate and the double strength criterion of weak plane-rock mass, a semi-analytical model for the stability of borehole with geological weak plane is established in this paper. This paper provides a theoretical basis for fully understanding the influence of geological weak plane occurrence and the parameters of various layers on the wellbore stability, and can effectively guide the safe drilling operation. In addition, the method of inversion of earth stress in complex strata is explored in this paper. The work carried out in this paper mainly includes: 1, taking rock samples with different forms of weak structural planes for laboratory uniaxial compression and ultrasonic testing to verify the weakening characteristics of rocks with weak surfaces. This paper provides an experimental basis for theoretical analysis and introduces a general method for obtaining formation parameter data from logging data, including the general formulas for obtaining the basic parameters of rock mass physics and mechanics. This paper expounds the method of obtaining the input formation parameters in the wellbore stability model, establishes the wellbore stability model with geological weak plane formation, obtains the solution program by using the programming software, and verifies the reliability of the solution program. The influence of different strength criteria on the calculation results is compared. Considering the generality of in-situ stress level and the influence of weak structure in rock mass on wall rock strength, the stability of horizontal well and inclined well under specific working conditions is calculated. The factors affecting the stability of the shaft wall are comprehensively analyzed, and the guiding suggestions for reasonable construction under complex working conditions are provided. The method of inversion of in-situ stress in complex strata by using the established model is explored. Because the borehole caving method is only suitable for the inversion of geostress in isotropic strata at present, this method can be used as an effective supplement to it in order to provide more abundant inversion data of in-situ stress.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE21

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