Although efforts are made to reduce or eliminate sand production in a producing well, sometimes sand fill is an unavoidable by-product of well conditions and the need for a cleanout intervention is necessary. Various cleanout methods have been utilized in the past, including the use of coiled tubing. Removing sand fill from a well using coiled tubing is one of the earliest applications for CT and continues to be an important service to the industry today.
Historically, coiled tubing cleanouts have incorporated high circulation rates, exotic/costly fluids and reverse circulation to remove solids. Many of these conventional sand cleanout methods often apply excess hydrostatic pressure on the formation, resulting in lost circulation in low formation pressure reservoirs. Incorporating large liner geometries with smaller completion restrictions magnifies the task at hand as the annular velocities are drastically reduced even with higher coiled tubing circulation rates.
Using a specially developed cleanout tool and a computer simulator for solids transport provides an opportunity to optimize the operation for the removal of solids to near 100% efficiency, with all fluidized solids being removed. Simplified operational procedures allow for making a more qualitative decision about the cleanout efficiency.
This paper will show cost effective solutions utilized in Saudi Arabia from 2007 to present by providing an overview of all field cases and job optimization. The main focus of the paper will be to highlight and compare the coiled tubing cleanout job design process, operational procedures, results, and lessons learned from two case studies; the first case study being a successful cleanout, while in the second case study the cleanout objective was not achieved.