Combining acid fracturing, propellant stimulations, and polymer technologies to develop additional reserves

The continuing use of combined crosslinked polymer, propellant, and acid fracturing treatment technologies has resulted in additional reserve development in a mature waterflood field in Wyoming. These three technologies have been used in combination on over 40 wells during 1996 and 1997 in the Oregon Basin Field, located in Park County, Wyoming, USA. The first use of Acrylamide-polymer/CrIII-carboxylate (gel) technology in Oregon Basin took place in the mid-1980s. The treatments were used to reduce water production in producing wells and improve both vertical and areal conformance in injection wells. Acid stimulations have been used since the 1940s as a means of improving production, with the first acid fracturing treatments being pumped in the late 1980s. Beginning in 1996, these two technologies were combined in an attempt to successfully increase oil production from wells that had not been considered acid stimulation candidates due to their total productivity. Propellant was used as a perforation breakdown technique after pumping the gel treatment and prior to the acid stimulation. This paper discusses the evolution of the gel and acid fracturing treatment designs, and the reasons for combining the two treatment techniques. The results of the 1996-1997 program are discussed in detail, as well as the changes in treatment designs that have taken place during the project. Data is presented that confirms accomplishment of the treatment objective.