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Published in Torgeir K. Haavik, New Tools, Old Tasks, 2017
Some shale types react with water from the drilling fluid and swell into an impermeable pulp that is not easily removed from the well and that may cause the drill string to get stuck in the well (differential sticking13). The prevention of differential sticking is connected to aspects of well control. One method of prevention is to drill with sufficient low mud weight to reduce the overbalance pressure.14 This is not completely unproblematic since overbalanced drilling is a central method of controlling the formation’s fluid pressure to prevent kicks.15
Recent advances in application of nanomaterials as additives for drilling fluids
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Rupali Gautam, Manisha Sahai, Sanat Kumar
Interaction between the wellbore and drill string while drilling generates excessive friction, drag and torque, resulting in severe drilling problems (Taurozzi, Hackley, and Wiesner 2010). The issue gets escalated with the increase in depth and bottom hole temperature or while drilling extended, directional, and horizontal wells (Loos 2015). It causes wear of bit, buckling of the drill string, over-pulls in trip-outs, differential sticking, equipment failure, and economic losses (Inkyo and Tahara 2004). Minimizing the coefficients of friction (COF) while drilling, by overcoming the friction and drag is crucial for the success of the whole operation (Hwang et al. 2008; J N 1991). Lubrication agents are added to the drilling fluid as additives to achieve a COF value as low as possible. A high lubricity drilling fluid offers other advantages as well, such as an increase in the rate of penetration and substantial cost savings (V A 2006). Enhancing the lubricity of drilling fluids using nano additives has been the focus area of several pieces of research.
Methodology of uncertainty analysis prediction based on multi-well data fusion
Published in Geosystem Engineering, 2018
Huan Jie Zhang, Kai Wei, Alain P. Tchameni, G. Ben-Kane
Drilling geological parameters are the basic data reflecting the comprehensive nature of the rock environment, which is of great importance during drilling engineering design and monitoring and avoiding drilling risk. Thus, the prediction of drilling geological parameters is crucial (Kai, Chuan, & Shan, 2015). However, due to the complexity of oil and gas geology, incompleted data explanatory, inaccuracy of mathematical model as well as geological parameters errors are avoidable resulting in uncertainty of geological parameters. The design of drilling fluid density during drilling process aims at not only to maintain borehole stability but also balance the differential pressure to avoid fluid from entering into the well favorable for well blowout, differential sticking, and so on. This then justify the accuracy for predicting the formation pressure in order to improve the rate of penetration, protection of oil layer, design wellbore structure, and drilling fluid density (Hai & Jin, 2002).
Effect of excess viscosifier and fluid loss control additive on the rheological characteristics of water-based drilling fluid
Published in Petroleum Science and Technology, 2023
Mike Uche Ajieh, Nosakhare Andrew Amenaghawon, Kesiena Owebor, Oghenero Henry Orugba, Esua Bassey Bassey
To efficiently apply drilling fluids for drilling operations, certain fluid characteristics are desired, such as the fluid density, rheological and filtration properties. Rheology is the study of fluid flow and deformation. It specifically relates shear stress to shear rate and the effects on the plastic viscosity, yield point and gel strength. These properties are very important for drilling fluids and largely account for the reason why fluids are suitable for drilling formations that have high porosity while attempting to maintain the rheological properties and not causing damage to crossed formations (Hamed and Belhadri 2009). Other properties include the ability to exhibit fluid loss prevention, stability of fluid under different temperature and pressure, and prevention of fluid contamination during operations, i.e., saltwater, calcium sulfate, cement and potassium. Nonetheless, it is of considerable importance for drilling fluid to exhibit high penetration properties, which enables fluid to wet the drill string and to keep clean the cutting surfaces of the drill bit. Essentially, a high degree of lubrication is key to minimizing friction between the drill string and the wall of the borehole, an extremely valuable outcome being the minimization of differential sticking (Pakdaman et al. 2019). The hydrostatic pressure of the drilling fluid column is sufficiently higher than the formation pressure so that the drill string is forced against the wall of the borehole and stuck. In addition, it is important for drilling fluid to have the ability to prevent shale/clay swelling of the formation, which is key to reducing drill string sticking, which results from preventing clays from absorbing water (Rafieefar et al. 2021a).