【作者】 周保中；

【导师】 孙玉学；

【作者基本信息】 大庆石油学院 ， 石油与天然气工程， 2003， 硕士

【摘要】 井壁不稳定是指钻井或完井过程的井壁坍塌，缩径或地层压裂。井壁不稳定是钻井过程中遇到的井下复杂情况之一，严重影响了钻井工作。 井壁不稳定的实质是力学不稳定。当井壁岩石所受的应力超过其强度时就会发生井壁失稳。其主要原因可归结为力学因素，化学因素和工程技术因素。但后两者都是影响井壁应力分布和岩石力学性能而造成井壁不稳定。 为了解决井壁不稳定问题，多年来我国广大工程技术人员做了许多研究工作，取得了可喜的成果，其发展水平已于国外研究同步，并在一些方面有所创新，形成了自己的特色。但因针对性强等原因，井壁稳定问题仍然没有根本解决。 吉林油田大情字井地区是近年来吉林油田重点勘探的区块。钻井过程中井塌时有发生，严重影响了该地区勘探开发的速度和质量。 本文根据地层岩石性能参数，运用弹性力学理论建立了井壁围岩力学模型，确定了在该地区钻井所需的合理的钻井液密度范围。同时研究了抑制性性强的有机硅钻井液，该钻井液是一种低固相、低密度体系，集聚合物钻井液的强抑制性和三磺钻井液抗高温性于一身，防塌效果好。通过力学和化学两方面的研究，为吉林油田井壁稳定技术的研究奠定了良好基础。更多还原

【Abstract】 Borehole instability includes well sloughing, formation fracturing and tight hole during drilling and completion. It is one of complicated situations encountered in drilling, which influences the drilling seriously.It is mechanical instability that induces borehole instability. If the stress that acts on shale around wellbore exceeds its intensity, borehole instability will happen. Its main reasons can be summed up as the mechanical factor, chemical factor and engineering technical factor. The last two factors induce borehole instability both by affecting stress distribution around wellbore and material properties of rock.The domestic researchers have made a lot of study on borehole instability for many years to solve it, and some important achievement is got. The achievement catches up with the international level and forms certain characteristics in some aspects. But wellbore instability has not been thoroughly solved for its complexity.Daqingzijing area is where Jilin oil field especially explores in recent years. Borehole instability often takes place during drilling. It severely affects the speed and quality of exploration and development in this area.This study sets up the mechanical model of rock around wellbore with elastic theory of mechanics based on formation properties parameters, determining the range of mud density for drilling in this area. Organic silicon drilling fluid with strong inhibition is also studied. It is low-solid-content and low-density system that has the advantages of polymer drilling fluid and sulfonation drilling fluid. It is effective in preventing well sloughing. This paper studies wellbore instability in mechanical and chemical sides and establishes solid foundation for studying wellbore stability of Jilin oil field.更多还原