岩溶地貌区浅层孔隙压力剖面的构建与钻探工艺探讨

Construction of Shallow Pore Pressure Profile and Exploration of Drilling Technology in Karst Landform Areas

摘要:

摘 要：岩溶地貌区浅部地层钻探过程中发生大量漏失、涌水等复杂情况，地层中广泛发育的缝洞网络形成了流体运移通道，而钻井液和地层水之间的压差也是重要的影响因素，常规孔隙压力预测方法无法对浅层孔隙压力实现有效表征。为探索岩溶地貌区浅层孔隙压力的实际分布情况，基于水文地质学和流体力学原理，构建了基于地下水实际分布的浅部地层孔隙压力剖面，并利用黔西探井钻探实例验证了剖面的有效性，结果表明岩溶地貌区浅层存在多个压力分区且与地下水的分布密切相关：地下水位以上为无孔隙压力；潜水层孔隙压力的计算应以地下水面为基线，是典型的低压区；承压水层的孔隙压力取决于补给区与排泄区位置差异，可能表现为高压、低压或常压。分析了堵漏材料、清水钻进及空气潜孔锤钻井在岩溶地貌区的适应性，建议在钻井设计中充分利用水文地质资料构建浅层压力剖面，据此选择钻井工艺或钻井工艺组合并确定一开次钻井深度，以避免钻井复杂情况，提高钻探效率。本研究能够为岩溶地貌区钻探工程设计与实施提供参考。

Abstract:

During the drilling process of shallow strata in karst landform areas, a large number of complex situations such as leakage and water inflow occur. The widely developed fracture and cave network in the strata forms fluid migration channels, and the pressure difference between drilling fluid and formation water is also an important influencing factor. Conventional pore pressure prediction methods cannot effectively characterize shallow pore pressure. To explore the actual distribution of shallow pore pressure in karst landform areas, a shallow pore pressure profile based on the actual distribution of groundwater was constructed based on hydrogeological and fluid mechanics principles. The effectiveness of the profile was verified using the Qianxi exploration well drilling example. The results showed that there were multiple pressure zones in the shallow layer of karst landform areas, which were closely related to the distribution of groundwater: there was no pore pressure above the groundwater level; The calculation of pore pressure in the groundwater layer should be based on the groundwater surface, which is a typical low-pressure zone; The pore pressure of a confined aquifer depends on the difference in location between the recharge and discharge zones, and may manifest as high pressure, low pressure, or normal pressure. Analyzed the adaptability of plugging materials, clean water drilling, and air down the hole hammer drilling in karst landform areas. It is recommended to fully utilize hydrogeological data in drilling design to construct shallow pressure profiles, select drilling processes or drilling process combinations based on this, and determine the depth of drilling for each opening to avoid complex drilling situations and improve drilling efficiency. This study can provide reference for the design and implementation of drilling projects in karst landform areas.