A new technique for cleaning horizontal wellbores

The plugging of horizontal wellbores can lead to significant loss of productivity and can nullify the benefit of a horizontal wellbore, which is expensive to create. Cleaning horizontal wellbores is a formidable challenge. The problem is particularly complex for heavy oil formations that show asphaltene, sand, and other difficult-to-remediate problems. This paper aims at developing a new technique that can effectively clean up a horizontal wellbore without requiring expensive workovers. The technique involves the use of ultrasonic treatment coupled with foam treatment. Initial experiments show that ultrasonic treatment can reduce plugging in two ways-the first is the reduction in oil viscosity (especially in the presence of asphaltic crudes) and the second is the ability of ultrasound to keep particles in suspension. The second effect can be due to the generation of microbubbles. The process is coupled with in situ generation foam. In order to generate foam, a particular type of surfactant is chosen from a selection of a wide range of surfactants supplied by the service companies. While the design of the device that couples both these effects needs to be optimized, an initial series of experiments shows good promises.