Successful Application of Innovative Technology Improves Lubricity of High Performance Water-Based Mud Systems in Challenging Environments

摘要

This paper describes the use of an innovative high-performance water-based drilling fluid system in south Europe.The novel drilling fluid allowed to successfully drill a sidetrack in a deep,high pressure-high temperature(HP-HT)well,in an area where low toxicity oil-based drilling fluids had been used in the past,due to the adverse drilling conditions. Comprehensive laboratory testing carried out to customize the drilling fluid formulation during the well planning phase,was complemented by further testing conducted during drilling operations.An obvious advantage of this system is its simplicity.It is composed mostly of liquid additives that allow a quick and easy preparation at rig site.The system is also compatible with the full range of mud densities,while exhibiting consistently superior lubricity characteristics. A tailored version of the system for this sidetrack well in southern Europe,required a heavy weighted fluid(up to 2.06 SG)to provide sufficient hydrostatic pressure for well control.The formulation included a high temperature rheology modifier that improved fluid stability at temperatures up to 160°C at total depth. A high performance lubricant was added to the system to improve drilling rate,while using an advanced steerable drilling system.Lubricity coefficients were monitored and recorded daily at rig site using a standard industry accepted ring and block type lubricity tester.The lubricity values fell in the range traditionally associated with oil-based mud usage.The successful sidetrack operations were completed with very good performances.