Geotechnical parameters required for estimating the maximum allowable annular pressure () in horizontal directional drilling (HDD) are often empirically determined based on the results from the standard penetration test (SPT). Despite the benefits of SPT, its use in practice could be challenging as the geotechnical parameters determined based on SPT results vary largely depending on the choice made for SPT correlations. Such variability within the geotechnical parameters could result in a high degree of uncertainty within the estimates of in HDD. In this paper, an SPT-based algorithm is developed to study the variation in estimates of geotechnical parameters and due to the choice made for SPT correlation. Sensitivity analysis conducted using the SPT-based algorithm presents significant variations in both estimates of geotechnical parameters (relative ranges vary from 11% to 1516%) and (relative ranges vary from 10% to 1313%) for cases where the understanding of soil behavior and characteristics is insufficient. Error analysis conducted based on the errors in the geotechnical parameters determined using SPT correlations and the corresponding estimates of presents that the two types of errors are found closely related for most cases; however, exceptions also exist for the cases with the SPT correlations related to modulus of elasticity. Based on the results of the error analysis, suggestions for the use of SPT correlations are made for determining the input geotechnical parameters required for estimating the in HDD, and they are applied to a case study related to the hydraulic fracture experiments to demonstrate their usefulness in a real-world example. The case study presents high precision (R > 0.81) in the estimates of obtained by following the suggestions for the use of SPT correlations. In remark, the estimates of made based on some SPT correlations are found nearly equal to the measurements of annular pressure at hydraulic fracture, confirming that the SPT-based algorithm and the suggestions for the use of SPT correlations provided herein are reasonably reliable for estimating the in HDD. These results highlight the challenges with using empirically determined geotechnical parameters in the design of HDD and provide practitioners with valuable information for evaluating the stability of the HDD borehole.

中文翻译：

---

使用经验确定的岩土参数进行水平定向钻井中井眼稳定性评估的挑战


估算水平定向钻井 (HDD) 中最大允许环空压力 () 所需的岩土工程参数通常根据标准贯入试验 (SPT) 的结果凭经验确定。尽管 SPT 有诸多好处，但其在实践中的使用可能具有挑战性，因为根据 SPT 结果确定的岩土参数在很大程度上取决于 SPT 相关性的选择。岩土工程参数的这种变化可能会导致 HDD 估计值的高度不确定性。本文开发了一种基于 SPT 的算法来研究岩土参数估计值的变化以及由于 SPT 相关性的选择而导致的变化。使用基于 SPT 的算法进行的敏感性分析显示，对于了解土壤行为和特点不够。根据使用SPT相关性确定的岩土参数的误差和相应的估计进行的误差分析表明，在大多数情况下这两类误差密切相关；然而，SPT 相关性与弹性模量相关的情况也存在例外。根据误差分析的结果，提出了使用 SPT 相关性来确定估计 HDD 所需的输入岩土参数的建议，并将它们应用于与水力压裂实验相关的案例研究，以证明其在一个现实世界的例子。该案例研究具有高精度（R > 0.81）通过遵循使用 SPT 相关性的建议获得的估计值。值得注意的是，基于一些 SPT 相关性所做的估计几乎等于水力压裂处环空压力的测量结果，证实了本文提供的基于 SPT 的算法和使用 SPT 相关性的建议对于估计在硬盘中。这些结果凸显了在 HDD 设计中使用凭经验确定的岩土参数所面临的挑战，并为从业人员提供了评估 HDD 钻孔稳定性的宝贵信息。