Knowledge of subsurface formation pressures is critical for the calibration of predictions and models needed for safe drilling of deep wells, historically for oil and gas wells. The same details apply to the sequestration of CO₂, ephemeral storage of gases such as hydrogen and for geothermal power. An estimated 10–14% of wells globally experience an unexpected influx of formation fluid, indicative of the controlling mud in the borehole at that time having a lower pressure than the surrounding formation. The drilling events, known as kicks and wellbore breathing, lead to, at best, downtime on the drilling rig which might affect the economic viability of the well, or in the extreme its safety with possible loss of life such as in the case of an uncontrolled blowout. Not all kicks are of equivalent value: dynamic and static kicks can be classified with a high degree of confidence and may become values for true formation pressure. Other types of fluid influx during drilling, including swab kicks and wellbore breathing, need to be identified and will not be accepted in a kick database. These types of influx may be eliminated as potential formation pressure values but, along with mud weights, can be valuable data to constrain the range of possible formation pressures, of significant where no other data exist. A new, rigorous evaluation procedure for determining formation pressure is presented, and compared with direct pore pressure measurements (e.g. RFT, MDT, RCI values). The comparison shows that the proposed methodology illustrates typical uncertainty of about 10 bar (145 psi) pressure over the full range of pressures for which data are available in this study.

Thematic collection: This article is part of the Geopressure collection available at: https://www.lyellcollection.org/cc/geopressure

了解地下地层压力对于校准深井安全钻井所需的预测和模型至关重要，历史上对于油气井而言。相同的细节适用于 CO _2的封存，氢气等气体的临时储存和地热发电。据估计，全球 10-14% 的井经历了地层流体的意外流入，这表明当时钻孔中的控制泥浆具有低于周围地层的压力。钻井事件，称为井喷和井眼呼吸，最多会导致钻井平台停机，这可能会影响油井的经济可行性，或者在极端情况下可能会导致生命损失，例如在不受控制的井喷。并非所有井涌都具有同等价值：动态和静态井涌可以高度可信地进行分类，并可能成为真实地层压力的值。钻井过程中其他类型的流体流入，包括抽吸和井筒呼吸，需要被识别并且不会被踢数据库接受。这些类型的涌入可以作为潜在的地层压力值被消除，但与泥浆重量一起，可能是限制可能地层压力范围的有价值的数据，在不存在其他数据的情况下具有重要意义。提出了一种用于确定地层压力的新的、严格的评估程序，并与直接孔隙压力测量值（例如 RFT、MDT、RCI 值）进行了比较。比较表明，所提出的方法说明了在本研究中可获得数据的整个压力范围内约 10 bar (145 psi) 压力的典型不确定性。在没有其他数据存在的情况下具有重要意义。提出了一种用于确定地层压力的新的、严格的评估程序，并与直接孔隙压力测量值（例如 RFT、MDT、RCI 值）进行了比较。比较表明，所提出的方法说明了在本研究中可获得数据的整个压力范围内约 10 bar (145 psi) 压力的典型不确定性。在没有其他数据存在的情况下具有重要意义。提出了一种用于确定地层压力的新的、严格的评估程序，并与直接孔隙压力测量值（例如 RFT、MDT、RCI 值）进行了比较。比较表明，所提出的方法说明了在本研究中可获得数据的整个压力范围内约 10 bar (145 psi) 压力的典型不确定性。

专题合集：本文是 Geopressure 合集的一部分，可在以下网址获得：https://www.lyellcollection.org/cc/geopressure