Successful Drilling of Oil and Gas Wells by Optimal Drilling-Fluid/Solids Control— A Practical and Theoretical Evaluation

Abstract

Summary Since the development of the drilling industry, the process for removing drill solids from the drilling fluid has culminated in the use of shaker screens as the primary or sole solution. It is, therefore, necessary to optimize both filtration efficiency and the screen life to hinder drilled solids from entering the drilling fluid. Optimum solids control can be obtained by using knowledge of how damage to the filtration cloth arises, of how to reduce it, and of how the particles in the circulation system influence the general picture of the drilling process. When this knowledge is accepted, established, and implemented in the drilling industry, it is possible to maintain efficient drilling. This paper describes, in detail, the theory and field examples on how wear arises on the shaker-screen cloth. As will be shown, this knowledge has been used to increase the solids-control efficiency and to reduce the screen wear by more than 90% in several field cases where 17½-in. sections have been drilled with oil-based mud. This has been achieved by use of a different screen configuration, running with top screens with finer cut points than normal. This leads to removal of 90 to 95% of the solids from the fluid using the top deck, thereby minimizing the wear on the finer bottom-deck screens. The documentation is based on practical off-shore results from these drilling operations, including data from the drilling log, laboratory analyses of the drilling fluid, and of the particle-size distribution (PSD) of the drilling fluid. The particular focus of this article is the application of double-deck shakers.