Mile Six Pool - An Evaluation of Recovery Efficiency

The Mile Six pool is located on the La Brea-Parinas Concession ofInternational Petroleum Co., Ltd., in northwestern Peru on the west coast ofSouth America. The reservoir pressure in this pool has been maintained within200 psi of its initial value throughout its history, and gravity drainage hasplayed an important role in the production behavior. It has now produced 95 percent of its estimated ultimate recovery. It is estimated that this interesting oil pool will ultimately produce 67per cent of the initial oil in place and that the resulting residual oilsaturation may be as low as 19 per cent of the pore volume (29 per cent of thehydrocarbon pore volume). An evaluation of reservoir rock and fluidcharacteristics and ultimate oil recovery is presented. Introduction This study of Mile Six pool was made to evaluate its performance accordingto latest available information. The production performance of this pool hasbeen discussed in various articles in the past, and the reported behavior hasbeen used as an example for application of computation procedures for gravitydrainage depletion and as an illustration of field behavior under gravitydrainage or expanding gas cap drive. There have been wide variations inreported values of initial oil in place, reservoir oil volume factor, connate-water saturation, volume of effective sand, and ultimate recoverybecause of the paucity of reliable basic data. These various factors have beendetermined as accurately as practicable with the latest available information, and this evaluation is presented herein. The production history of Mile Six isan excellent example of gravity drainage depletion with effective pressuremaintenance by gas injection. General Mile Six pool was discovered by cable-tool drilling in November, 1927, whenwell 1996 was completed in the Parinas sand. After slow development with cabletools and sporadic production, the pool was opened to continuous production inNovember, 1933, and development was completed with rotary rigs. Pressuremaintenance was started in December, 1933, by returning gas to up structurewells. Most of the development was completed by 1937, but some additional wellswere drilled in the period 1939–1947, and several old wells were deepened. Atotal of 46 oil and gas wells and 4 dry holes were drilled on approximately7-acre spacing. Of the producers, 21 are now flowing, 2 are pumping, 4 are gasinput wells, 3 are abandoned, 1 is a gas well shut in, and 15 are shut inbecause of non-commercial production or high gas-oil ratio. The locations ofall wells are shown on the map of Fig. 1. T.P. 3695