Emulsion Flooding of Viscous Oil Reservoirs

Abstract

This paper was prepared for the 48th Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Las Vegas, Nev., Sept. 30-Oct. 3, 1973. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract An evaluation of stable water in oil emulsions (200 cp oil) at 180 degrees F as displacing agent is presented. The stability of emulsions as controlled by the pH of water. Displacement tests were carried out in consolidated Berea sandstone cores at a temperature of 180 degrees F. Secondary as well as tertiary recovery tests were conducted by injecting emulsion slugs followed by polymer solutions in order to control the mobility ratio. It was found that emulsions prepared with law pH water in a viscous oil were stable during the displacement process, and were able to recover up to 97 percent of the original oil at an approximate cost of 1 $ per barrel of extra oil with no need of a commercial emulsifier. Slugs of emulsion greater than 4 percent of the pore volume were able to maintain the displacement pore volume were able to maintain the displacement miscible during the whole process, recovering up to 7.5 barrels of extra oil per each barrel of oil in the emulsion when the mobility ratio was properly controlled. properly controlled Introduction Microemulsion flooding is a miscible oil recovery process which involves sequential injection of a process which involves sequential injection of a slug of microemulsion, a mobility buffer and water. The viscosity of the microemulsion and the buffer can be controlled in such a way that the mobility ratio is favorable during the displacement achieving high volumetric efficiency. The chemistry of microemulsions and their behavior in oil-water displacement tests are the most important aspects in the process. process. The use of microemulsions for secondary and tertiary recovery of oil have been presented in the literature. Laboratory as well as field tests have established their use as an important miscible method which is technically feasible. However the high cost of surfactant used in preparing microemulsions have limited its application in the field. Slug costs of 4 $/Bbl have been reported by Gogarty and Surkalo; they also indicated that in a large field test, the total cost of producing tertiary oil would be around 2.50 $/Bbl using micellar solutions. This work presents experimental tests showing that it is possible to prepare stable emulsions with some crude oils that can be used for secondary and tertiary recovery of oil without the requirement of commercial emulsifiers consequently reducing the cost of microemulsion slugs and thus improving the economics of the process. process.