Fracturing With Viscoelastic Surfactant Fluid in Cyclic Steam Injection Wells - A Synergy for Heavy Oil Recovery

摘要

Unconventional oil sources have became one of the most important keys for maintaining the world energy supply. Considering the increasing contribution of the crude below 15 deg. API in the worldwide oil reserves, one aim should be technology development to improve oil production and increase reserves recovery from such reservoirs. One of the most used technologies in hydrocarbon recovery is hydraulic fracturing. On the other hand, cyclic steam injection is a widely used technique to improve recovery from heavy oil reservoirs. This paper describes an example where hydraulic fracturing using anionic viscoelastic surfactant fluids has been combined with cyclic steam injection to synergistically improve production results in a mature heavy oil field. After several years of performing these treatments, this synergy has led to larger heating coverage and therefore improved viscosity reduction of the crude; higher than 100% regained permeability; creation of a very low-viscosity dispersion of the oil in water; and asphaltene dispersion. Such findings are supported by laboratory testing results and backed by post-treatment production results in the heavy oil reservoir where this fracturing campaign was performed and the results analyzed. The observations in the laboratory, their analysis, and the match with field data demonstrate that combining a properly designed stimulation treatment using anionic viscoelastic surfactant with steam injection have led to significant improvements in the stimulation of this heavy oil reservoir. They also show that such results are applicable to other reservoirs where high-viscosity reservoir fluid is a challenge.