On the role of the Bernoulli force in stuck pipe during oil and gas well drilling

Stuck pipe is one of the most prevalent and costly complications encountered during drilling operations in the oil and gas industry. It represents a significant challenge, contributing to delays and increased financial costs that cumulatively amount to billions of dollars annually. Understanding and addressing the root causes of pipe sticking are crucial for minimizing these adverse impacts. This paper provides a comprehensive analysis of the various factors contributing to stuck pipe incidents, highlighting both traditional and newly identified mechanisms. Key factors leading to pipe sticking include mechanical issues such as rock particles drilled out during the process, inadequate well cleanup, wellbore instability, and differential sticking forces, which are primarily due to the disparity between hydrostatic pressure and formation pressure. These issues are particularly prevalent in horizontal or inclined wells, where the dynamics of drilling differ significantly from vertical wells, exacerbating the risks of pipe sticking. The occurrence of stuck pipe not only increases the duration of drilling operations but also significantly escalates the associated costs, thereby impacting the overall economic viability of drilling projects. A novel factor contributing to stuck pipe is the Bernoulli force, a phenomenon that has been discussed in detail in this article. The Bernoulli force acts perpendicular to the flow axis from the edges towards the center of the flow. In the context of cylindrical flow within a wellbore, this force is magnified as the density difference between the drilled rock particles and the drilling fluid increases, along with the diameter of the mechanical cuttings. As a result, the Bernoulli force facilitates the migration of drilled rock particles towards the flow center, leading to an accumulation that increases local resistance due to friction. This intensified resistance can significantly contribute to the occurrence of a stuck pipe, presenting a new challenge for drilling operations that must be addressed. This paper discusses the comprehensive mechanisms of stuck pipe, including the differential and mechanical factors, and provides an in-depth analysis of these aspects. The study emphasizes the importance of understanding these factors to develop effective strategies for prevention and mitigation. By exploring the key features necessary to minimize the risks associated with differential and mechanical sticking, this article offers valuable insights into improving well drilling practices. The findings underscore the need for thorough well cleanup, effective management of wellbore instability, and a nuanced understanding of pressure dynamics to prevent stuck pipe incidents. The paper concludes with recommendations for industry practices and further research to mitigate the impact of stuck pipe on drilling operations.