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 in weak side of deep stratified reservoirs

摘要:

深部储层油气藏资源储量丰富，由于复杂的地质因素、工程因素制约着深部油气藏安全高效开采。井壁失稳导致的卡钻、井塌、井漏等一系列问题给钻井工程造成巨大损失。本文在分析井壁失稳力学机理上，着重论述力学及其多场耦合下对井壁失稳影响机制，最后提出促进深部含层理弱面钻井理论技术的建议。研究发现：层理弱面发育、高温高压环境、地层倾角改变、岩石水化作用等因素是导致岩石力学强度弱化、深部储层井壁失稳的主要影响因素。不同倾角下的岩石力学强度存在巨大差异，含层理弱面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。本文较为系统地对井壁岩石力学及相关方面的研究进行了归纳，可深入了解深部储层井壁稳定性力学影响机制，为实际生产与工程实际提供参考。

Abstract:

Deep reservoirs with abundant oil and gas resources are difficult to exploit safely and efficiently due to complex geological conditions and engineering factors. The problems of stuck drilling， well collapse， and well leakage caused by unstable wellbore walls have led to huge losses to drilling engineering. Therefore， this paper analyzes the mechanical mechanism of unstable wellbore walls and focuses on the influence mechanism of mechanics and multi-field coupling on unstable wellbore walls. Finally， it proposes suggestions for promoting the theoretical and technical development of drilling in weak side of deep stratified formations. The study found that the development of weak side， high temperature and high pressure environment， changes in rock layer inclination， and hydration of rocks are the main factors that weaken the mechanical strength of rocks and cause instability of the wellbore walls in deep reservoirs. The mechanical strength of rocks under different inclinations is significantly different， and the weak side of stratified rocks is more likely to swell due to hydration， which requires the rational optimization of drilling engineering parameters and drilling fluid density. This paper systematically summarizes the research on the rock mechanics and related aspects， deeply understands the mechanical influence mechanism of wellbore wall stability in deep reservoirs， and provides reference for actual production and engineering practice.