Performance of the Fry In-Situ Combustion Project

Abstract
A pilot operation, reported on at the 1964 SPE Annual Fall Meeting, has been converted into an expanded field operation. This updates the earlier report and concludes that, although the economics is not favorable, the project continues to be a technical success and does show a day-today project continues to be a technical success and does show a day-today operating profit. Introduction The Fry combustion project in Crawford County, Ill., changed from a pilot test to a field-wide operation at the beginning of 1964. This paper will cover the field operation and production behavior for the total project from the ignition of the pilot (Oct., 1961) to the project from the ignition of the pilot (Oct., 1961) to the present. Information about the operations and present. Information about the operations and performance of the pilot was presented by Clark et al. performance of the pilot was presented by Clark et al. Reservoir geology was discussed by Hewitt and Morgan. Additional production data from the expanded operation were given by Poettmann et al. to illustrate some of the technology involved in the analysis of the combustion process, particularly in light oil reservoirs. The main purpose of this paper is to update the production histories through 1968 and to show the effect production histories through 1968 and to show the effect that various procedures have had on production. Reservoir Properties The Fry reservoir has been described as a lenticular, southwest trending Robinson sandstone body of Lower Pennsylvanian age. It is of fluvial origin and part of an extensive complex of river sediments. Fig. 1 shows the present version of the net sand isopachous map, which has been revised as new wells were drilled during the expansion program. Portions of the reservoir, mainly to the west, are not shown since they have not been affected by combustion. The four air injection wells are located to show their relationship with respect to the reservoir geometry. The reservoir sand is usually fine- to mediumg-grained, with quartz, feldspar, and muscovite as the predominant minerals. Accessory minerals include kaolinite, illite, calcite, siderite, pyrite, and carbonized plant fragments. The sand can be subdivided into four distinct structural units. A zone Small-scale, trough-shaped ripple structures. Very-fine to fine-grained. Generally less than 5 ft thick. Maximum thickness - 11 ft. B zone - Cross-stratification sets ranging from 0.5 to 4 ft thick (average, 1 ft). Fine to medium grained. Occurs over entire reservoir area. Greater than 30 ft thick in some areas. C zone Mixed sandstone-shale laminae lithology. Individual sand layers 0.1 to 0.5 ft thick. Medium grained. Occurs in central portion of reservoir, not extending to NW or SE boundaries, not quite extending to Well AI-2. Greater than 20 ft thick around and somewhat north of Well AI-1. M zone Massive, structureless sandstone. Medium grained. Occurs only around Well AI-2. Very small overlap between areas of the C and M zones. twelve feet noted in one well. This zone has been detected since the original publication. Table 1 is a summary of average core analysis data from seven wells spread throughout the field. These data indicate that the reservoir is fairly uniform. However, core analysis permeabilities tell little of the effect of structural features on over-all permeability. The probable existence of a directional permeability due to structural or grain orientation effects has been noted previously, as have other effects of geology on previously, as have other effects of geology on reservoir performance. JPT P. 551

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