Laboratory investigations in the Use of Polymers in Low Permeability Reservoirs

Abstract

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. This paper was prepared for the 49th Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Houston, Texas, Oct. 6–9, 1974. 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 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. 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 discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract With the recent crude oil price increases, many oil producers are showing greater interest in the use of polymers for secondary and tertiary recovery. Many of the reservoirs under consideration are very low permeability sandstones and limestones. Because of the large size of the polymer molecules considered, the use of polymers in tight formations must be closely scrutinized. Presented in this paper are laboratory results investigating the viability of polymer treatment in low permeability sandstone and carbonate field cores. Polymer resistance factor, residual resistance factor, and retention data are reported for a partially hydrolyzed polyacrylamide and for a new copolymer of polyacrylamide and for a new copolymer of acrylamide. Tests were conducted at temperatures ranging from 136 degrees F - 180 degrees F. Frontal advance rates during displacement tests ranged frown 1.5 - 6 ft./day. In comparing the field reservoir cores evaluated, a considerable difference was seen in the behavior of polymers in sandstone versus limestone. The hydrolyzed polyacrylamide evaluated was able to penetrate low permeability limestone cores but caused severe permeability limestone cores but caused severe plugging in sandstone cores of similarly low plugging in sandstone cores of similarly low permeability (K air = 7 md - 59 md). In the permeability (K air = 7 md - 59 md). In the case of sandstone the copolymer of acrylamide was able to penetrate low permeability cores while hydrolyzed polyacrylamide of the same viscosity could not. Effect of high flow rate degradation of polymer solutions in porous media (150 - 8,000 polymer solutions in porous media (150 - 8,000 ft./day) is also presented. Frontal advance rates required for shear degradation of polymer solutions are shown, Rate of polymer injection through perforations in thin reservoirs should be closely controlled to prevent polymer degradation in the immediate vicinity of the injection well. Information, such as effects of temperature and oxygen on polymer solutions, is reported. Additives are suggested to maintain or increase polymer solution viscosity without significantly polymer solution viscosity without significantly changing the injectivity of the polymer. Introduction Under proper conditions, polymers can enhance secondary oil recovery.