Conventionally, the same best practices from coiled tubing cleanout interventions in vertical wells have been applied to horizontal wells; pumping a high volume of viscous gel sweeps and performing a number of wiper trips in an effort to remove debris from the wellbore. Very often this practice leaves a significant amount of solids behind as a result of inadequate fluid rheology, increasing not only the risks of the operation but the overall completion cost of the well, while falling short from accomplishing the main objective of the Coiled Tubing (CT) intervention.
With the added pressure of reduced oil prices, operators are looking for ways to increase efficiency and reduce cost. Larger diameter CT has recently been used to perform millouts due to its improved set-down force and increased annular velocities for cleanout purposes. Service companies and operators have reduced the amount of wiper trips when using larger diameter coil to save time and money. Milling efficiency using 2 inch CT can be drastically improved by maintaining proper fluid rheology throughout the operation. By doing so, 2 inch CT has been used to successfully perform single trip millouts reducing operational time by 40%.
This paper will provide an analysis of the theoretical process and time comparison of multiple verse single trip millouts using 2 inch CT. The fluid rheology required to adequately clean out horizontal wells relies on the effective utilization of chemicals and correct fluid control throughout a given operation.