Abstract
One of the most common applications of coiled tubing is the removal of sand or other debris from wells. The typical operation involves circulating fluids down the coiled tubing and up the well. The fluids are designed to carry the sand from the bottom of the well to surface, without killing or over pressurizing the well.
Because most sand producing wells are under pressurized, gas is typically required to keep the hydrostatic weight of the return fluid column under that which the reservoir can support. This gas is typically nitrogen. Difficulties arise in many locations around the world where the supply of nitrogen is problematic, or at least very expensive. A cleanout method that does not require nitrogen removes the need for a timely, reliable and cheap source of nitrogen as well as the need for cryogenic pumps and tanks.
This paper details the use of concentric coiled tubing and a down hole jet pump to conduct cleanouts in the balanced or underbalanced condition without the use of nitrogen. This technique has been the subject of previous papers, demonstrating its applicability in difficult, deviated well profiles. This paper describes the enhancements made to the system to make it suitable to simple wells, focusing on low-cost, lower-tech operations as opposed to difficult applications. The first case histories are included.
