页岩强度弱化规律及对水平井井壁稳定的影响

发布时间：2018-04-04 13:40

本文选题：页岩　切入点：直剪试验　出处：《钻采工艺》2017年03期

【摘要】：为了揭示页岩本体和层理面力学强度特性及弱化对井壁稳定影响,基于直剪试验并结合弱面强度准则,分析了页岩抗剪强度参数的弱化规律。研究结果表明,水基钻井液浸泡下页岩本体和弱面强度均显著降低,且水基钻井液对弱面弱化影响大于对本体强度的影响。随着浸泡时间增加页岩强度逐渐降低,且最低强度逐渐左移;发生弱面破坏的角度范围逐渐增大;随着围压升高,页岩强度升高且发生弱面破坏的角度范围逐渐变小。坍塌压力与水平井钻进方位、弱面产状密切相关,其差异最高达到0.444 1 g/cm3,整体上水平井井眼沿着最小水平地应力方位钻进时井壁稳定性最好。随井眼钻开时间增加,当量坍塌压力逐渐升高。研究结果可为页岩气水平井钻井设计提供参考依据。
[Abstract]:In order to reveal the mechanical strength characteristics of shale body and bedding plane and the influence of weakening on wellbore stability, the weakening rule of shale shear strength parameters is analyzed based on direct shear test and weak plane strength criterion.The results show that the strength of shale body and weak surface decreases significantly under immersion of water-based drilling fluid, and the influence of water-based drilling fluid on weakening of weak surface is greater than that on bulk strength.With the increase of soaking time, the shale strength decreases gradually, and the lowest strength gradually shifts to the left; the angle range of weak plane failure increases gradually; with the increase of confining pressure, the shale strength increases and the angle range of weak plane failure becomes smaller.The collapse pressure is closely related to the drilling azimuth and the occurrence of weak plane in horizontal well, and the difference is up to 0.444 g / cm ~ 3. Overall, the stability of borehole is the best when drilling along the minimum horizontal stress azimuth.With the drilling time increasing, the equivalent collapse pressure increases gradually.The results can provide reference for drilling design of shale gas horizontal well.
【作者单位】：中国石油川庆钻探工程公司钻采工程技术研究院;中国石油川庆钻探工程公司塔里木工程公司;
【分类号】：TE243

【相似文献】