Performance of a Mexican Carbonated Reservoir and a Study of Opportunities to Increase Oil Recovery by Waterflooding in a Portion of the Reservoir

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 This paper summarizes the development and performance of Tamabra reservoir, Jiliapa field. performance of Tamabra reservoir, Jiliapa field. The reservoir, a dolomitic limestone, has two zones of different characteristics; one has an effective natural water drive and the other has mainly operated under solution gas drive. The initial oil in place was obtained by material balance after some tests to detect random or systematic errors in the basic data or in the mathematical process. History matching of the primary behavior was obtained by changing the effective compressibility in the undersaturation period and introducing a factor in the material-balance equation to compensate for the effect of produced free gas in some areas during the undersaturation stage. This paper also presents a study for increasing the oil recovery and for diminishing the production time by waterflooding in the reservoir portion not affected by the aquifer. The response of the reservoir was calculated with a flowline technique derived from that proposed by Leblanc and Caudle to consider an proposed by Leblanc and Caudle to consider an initial gas saturation and a variable water saturation within the flow channels. The best waterflooding pattern was obtained with a two dimensional model where the formation heterogeneities were simulated. Introduction In Feb. 1958, with the completion of JIL-2, initial oil production was obtained from the Jiliapa field, which is situated in the northwest corner of the state of Veracruz, Mexico, 25 km (16 miles) from Poza Rica. The pool, whose area comprises about 27 sq km (6,662 acres), has produced 3.5 MM cu m at S.C. (22 MM STB) as of produced 3.5 MM cu m at S.C. (22 MM STB) as of Dec. 1973. This represents a little more than 12 percent of the original oil in place 28.8 MM cu m at S.C. (181 MM STB). The structure, found at an average depth of 2,771 m (7,450 ft), was developed from Feb. 1958 to March 1964 by the drilling of 112 wells on 400-m (40-acre) spacing, 19 of which were dry holes. At present, the number of wells still producing from the Tamabra reservoir has producing from the Tamabra reservoir has diminished due to a strong natural water influx that forced the closure of several wells in the western zone of the reservoir. Laboratory analysis revealed that Jiliapa crude is undersaturated at initial reservoir conditions with a solution GOR of 112.5 cu m/ cu m (628.6 scf/STB) and a saturation pressure of 168.2 kg/sq cm (2,388 psi).