Fast, Environmentally Sound and Efficient Well Clean-Up Operations: Lessons Learned and Best Practices from Operations Around the World

Abstract

Well clean-up is one of the most complex operations performed at the wellsite today. During clean-up, a well is flowing for the first time after initial completion or workover operations through temporary surface facilities to either conduct a welltest or to simply condition the well before connecting it to production facilities. Currently, there are no practical recommendations available that would summarize clean-up experiences and guide operating companies through the process of efficiently planning well clean-up operations. Conventional well clean-up operations are inherently challenging owing to the requirements for accurate data measurements, safe handling and disposal of produced fluids (hydrocarbons, completion brine, water, and solids). Experience has shown that it is nearly impossible to perform well clean up within pre-defined constraints and target criteria without an appropriate design, equipment selection and operations planning to account for the specificities of each situation. Steady-state flow simulators have been the standard tool to model pressure and temperature changes along the wellbore and through temporary production system during well clean-up process. Those assume either final stabilized conditions or a limited number of intermediate ones and formed the basis for equipment selection. But this approach has critical limitations in modelling flowing well behavior and fast-changing flowing conditions, and therefore in assessing operational flow assurance risks and the dynamic capability of the surface plant to handle produced fluids. The paper describes in detail today's challenges during well clean-up operations that combine the need for operational safety, minimal environmental footprint and flow assurance considerations that have to be balanced with costs and production performance optimization. The paper provides practical recommendations and presents multiple case studies highlighting the results and lessons learned from applying a novel, unique workflow based on the application of a transient-multiphase flow simulator. Combined with modern well-testing equipment such as modern test separators, remotely actuated adjustable chokes or environmentally friendly fluid disposal techniques, such advanced design allows performing clean-up operations efficiently while remaining within time, rates, pressure or emissions limits.