Well Testing to Full Potential: Lessons Learned and Best Practices for High Rate Wells

Abstract

Today many well test operations are performed in frontier environments targeting high potential oil and gas reservoirs or using high deliverability horizontal wells. Such highly productive wells cannot be dynamically evaluated to acquire representative reservoir data by small-scale flow tests. High flow rate well tests are introducing a set of unique challenges that need to be addressed at the design stage of the test, each requiring an appropriate surface well test spread, DST string as well as job operation procedures and equipment planning. Currently, well tests aiming at achieving very high flow rates are often designed and executed on a case-by-case basis, and there are no practical recommendations available that would summarise the well testing experience in such environments and guide the operator through the process to efficiently plan the well test operations. Well test operations are inherently challenging operations owing to the requirements for well control, accurate data acquisition, and the safe handling and disposal of produced fluids (hydrocarbons, completion brine, water, and solids), concerns are especially acute when considering high flow rates. Several past experiences have clearly shown limitations when trying to achieve high flow rates using conventional approaches and standard well test equipment. Concerns range from equipment failure and operational issues to poor interpretability of acquired data from those tests, increasing the total costs of such well tests or in extreme cases leading to severe HSE incidents. Enhancements in well testing equipment such as new generation well test separators equipped with high-range Coriolis mass flow meters or new generation burners, combined with fit-for-purpose well testing techniques make it possible to overcome these challenges. This paper will summarise the results and lessons learned from high flow rate well test operations performed around the globe on vertical and horizontal wells, in oil and gas reservoirs. The paper provides practical recommendations supported by a series of case studies from multiple oil and gas fields. The paper also describes a comprehensive list of challenges associated with high rate well test operations that can support successful operations design. Recipes for success are provided to ensure that safe operation can be performed in challenging environments.