Sand production is a common problem faced by many of Canada's heavy oil producers. While slotted liner completions act as a partial barrier, grading effects at the slots often still result in sand migration into the wellbore. Low production flow rates and increasing numbers of horizontal completions both contribute to increased deposition of sand with the wellbore. Several cleanout options have been developed over the years employing a number of different technical approaches. Some of the challenges faced by these operations are low formation pressures and high viscosity in-situ oil. As none of these "current" systems have been found to be completely successful or cost effective, development efforts have continued. The evolution of coiled tubing technology has brought bout a unique solution to this problem. Concentric Coiled Tubing (CCT) strings are now available that open the door for using advanced clean out equipment such as jet pump tools. A patented jet pump design (Sand-Vac ™) has been developed specifically for the purpose of cleaning sand out of low pressure horizontal wells with concentric coiled tubing. This paper will discuss cleanout issues and objectives faced by the heavy oil producers in Western Canada. A review of current techniques will be followed by design and operating issues pertaining to the Sand-Vac ™ system. To summarize, a review and discussion of actual Sand-Vac ™ field applications will be given.
Large strides have been made in coiled tubing technology in the past decade. Higher quality products better operating skills and imaginative problem solving applications have made coiled tubing an integral part of today's oil and gas industry. With the introduction of the Sand-Vac ™ system and Concentric Coiled Tubing (CCT) the oil and gas industry have another option for cleaning sand out of their horizontal completed wells.
The Sand-Vac ™ system allows:
continuous cleaning operations
no moving parts down hole
proven jet pump technology
steady down hole pressure generation
This paper will discuss Sand-Vac ™ system and its applications.
Concentric coiled tubing has grown out of this progression (Figure 1), taking advantage of the new generation of large diameter coiled tubing (50.8 mm (2"), 60.3 mm (2 3/8"), 73.0 mm (2 7/B") and BB.9 mm (3 1/2"). Coiled tubing operators have been able to build permanent "tubing in tubing" strings to provide a whole new range of services to coiled tubing customers.
In most concentric coiled tubing applications the objective is the creation of an additional flow path in the work string. These string configurations can be tailored lo the specific application requirements by choosing internal and external pipe sizes La optimize circulation rates and minimize the risk of collapse.
Figure 1 - Concentric Coiled Tubing (Available in full paper)