Abstract Pore pressure predictions from the drilling parameters have experienced little improvement since the inception of the d-exponent concept. Applications of the d-exponent method to pore pressure predictions have produced mixed results, especially in deviated wells and under drilling conditions where bit hydraulic energy has significant influence on the rate of penetration (ROP). In this paper, a new energy-based pore pressure prediction technique using the concept of hydro-rotary specific energy (HRSE) is presented. The HRSE approximates the total energy required to break and remove a unit volume of rock. Overpressure prediction using the HRSE method is based on the principle that overpressure intervals with lower effective stress will require less energy to drill than the normally pressured intervals at the same depth. The new technique is tested using a recently drilled deep vertical exploratory gas well in the Tertiary Deltaic System in the central swamp region of the Niger Delta in Nigeria. The pore pressure estimates from the HRSE concept are compared to: (1) the pore pressure estimates derived from the d-exponent and shale compressional velocity, (2) the actual pore pressure measurements taken in the reservoir sands of interest. An excellent agreement is observed in magnitude and trend between the pore pressure estimates derived from the HRSE concept and the actual pore pressure measurements. This clearly demonstrates the applicability of the HRSE concept in predicting the onset of overpressure and estimating the formation pore pressure. The HRSE method of overpressure prediction has the potential to be more accurate in some drilling environments where the d-exponent method may have produced erroneous results.

中文翻译：

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使用水力旋转比能概念预测超压

摘要 自 d 指数概念出现以来，根据钻井参数预测孔隙压力几乎没有改进。d 指数方法在孔隙压力预测中的应用产生了不同的结果，特别是在斜井和钻头水力能量对钻速 (ROP) 有显着影响的钻井条件下。在本文中，提出了一种使用水力旋转比能 (HRSE) 概念的基于能量的新孔隙压力预测技术。HRSE 近似于破碎和移除单位体积岩石所需的总能量。使用 HRSE 方法进行超压预测的原理是，有效应力较低的超压层段比相同深度的常压层段所需的钻探能量更少。新技术在尼日利亚尼日尔三角洲中部沼泽地区第三纪三角洲系统中最近钻探的一口深垂直勘探气井进行了测试。HRSE 概念的孔隙压力估计值与：(1) 由 d 指数和页岩压缩速度得出的孔隙压力估计值，(2) 在感兴趣的储层砂岩中进行的实际孔隙压力测量值进行比较。从 HRSE 概念推导出的孔隙压力估计值与实际孔隙压力测量值之间在幅度和趋势上观察到极好的一致性。这清楚地证明了 HRSE 概念在预测超压开始和估计地层孔隙压力方面的适用性。