Stop, Drop and Circulate; An Engineered Approach to Coiled Tubing Drillouts

Abstract

Abstract In 2015, Devon Energy spent $60 million on post-stimulation drillouts. The average cost of a drillout was $250,000 when no issues were encountered. However, drillouts with significant issues cost an average of $1.7 million. In November 2015, the Drillout Group (DOGs) was formed to study and find solutions for issues associated with coiled tubing drillouts. The team consisted of 15 completions and drilling engineers directly involved in coiled tubing drillouts. The team met for eight months and invested more than 1,000 hours of engineering time. The DOGs visited with more than a dozen vendors, took three field trips and conducted laboratory experiments on various fluid systems. This paper examines the history of coiled tubing drillouts at the operator and how stuck events were considered to be a normal aspect of operations. The DOGs team was tasked with engineering a solution to coiled tubing drillouts and formulating a Best Practice (BP) to apply companywide to minimize "train wrecks." The primary focus of the DOG team was to create standards for coiled tubing jobs including the target Reynolds numbers, annular velocity, chemicals, viscosities, torque and drag, early warning signs and corrective actions to prevent stuck pipe. The paper evaluates the implementation of a real-time monitoring station and the results from 50 wells drilled out following the DOG best practice. The new best practice and live monitoring station resulted in average savings of $100,000 and average drillout time of 21 hours per well with zero stuck or sticky events recorded.