深部含层理弱面储层井壁失稳力学研究进展

Research progress on wellbore instability mechanics of deep stratified weak face reservoirs

摘要:

深部储层气藏资源储量丰富,但由于复杂的地质条件,如孔裂隙以及裂缝发育,层理弱面的存在等因素致使井壁失稳一直阻碍深部油气藏安全高效开采,井壁失稳导致的卡钻,井塌,井漏等一系列问题会给工程带来巨大损失,因此全面了解井壁失稳机理及研究进展十分重要,本文从井壁稳定性出发,从力学机理及发展历程进行总结。研究发现：层理弱面发育,多因素地应力,岩石物理力学参数,孔隙裂缝存在等因素是导致的力学强度弱化,深部储层井壁失稳的主要影响因素。对于含层理弱面地层,井壁失稳更加明显,不同倾角下的岩石力学强度存在巨大差异,沿层理面间岩石更容易发生水化膨胀,需合理优化钻井工程参数以及钻井液密度。本文较为系统对井壁稳定性力学及相关方面的研究进行了归纳,以便更好的深了解深部储层井壁稳定性力学机制,为实际生产与工程实际提供参考。

Abstract:

Deep reservoir gas reserves are abundant. However, due to complex geological conditions, such as the development of holes and fissures, the existence of weak bedding surface and other factors, shaft wall instability has always hindered the safe and efficient exploitation of deep oil and gas reservoirs. A series of problems such as stuck drilling, well collapse and leakage caused by shaft wall instability will bring huge losses to the project. Therefore, it is very important to have a comprehensive understanding of the mechanism and research progress of borehole instability. In this paper, starting from the stability of borehole, the mechanical mechanism and development history are summarized. It is found that the development of weak bedding surface, multi-factor ground stress, rock physical and mechanical parameters, the existence of pore cracks and other factors are the main factors that lead to the weakening of mechanical strength and the instability of deep reservoir wall. For strata with weak bedding surface, the wellbore instability is more obvious, and the mechanical strength of rocks at different inclination angles is greatly different, and the rocks are more prone to hydration expansion along the bedding surface. Therefore, drilling engineering parameters and drilling fluid density should be reasonably optimized. This paper systematically summarizes the research of borehole stability mechanics and related aspects, in order to better understand the mechanical mechanism of deep reservoir borehole stability, and provide reference for practical production and engineering practice.