Overview of Solids Transport Studies and Applications in Oil and Gas Industry – Experimental Work

Abstract

Abstract The transport of solids is encountered in well bore drilling, completion, intervention and production operations. It is affected by many variables and the complexity of the process presents challenges to the field engineer who is trying to determine how these parameters affect solids-transport even if only one of these variables is changed. Historically, solids-transport studies focused mainly on determining the minimum critical velocity to prevent the formation of a stationary debris bed in the wellbore annulus for conventional rotary drilling with mud fluids. Over the past 10 years, the research and development focus has been on obtaining information related to the prediction of the equilibrium solids concentration profile along the whole well path during tripping in, the wiper trip speed during tripping out, and the prediction of the hole-cleaning time. Various computer models have been developed that, to some extent, guide the field engineer in the design and optimization of the solids transport process. However, due to its complexity and incomplete experimental data, a comprehensive, proven and reliable model still does not exist at present. In this paper, based on 20 years of research experience, the authors present a review of previous approaches to the study of solids transport in both drilling and well interventions with emphasis on experimental studies. An overview of the theoretical study of solids transport is presented in a companion paper (Li and Luft, 2014). The basic tests required to collect comprehensive laboratory data in support of the development of a semi-empirical theoretical model to simulate the hole cleaning process, are also discussed. To date there is still no satisfactory solids transport software model commercially available for the oil industry. This paper provides some insight into and understanding of the complexity of the solids transport process, a general guide for necessary laboratory testing and some recommendations for future research related to this subject.