Performance of a Forward Steam Drive Project-Nugget Reservoir, Winkleman Dome Field, Wyoming

Abstract

Performance of a Forward Steam Drive Performance of a Forward Steam Drive Project-Nugget Reservoir, Winkleman Project-Nugget Reservoir, Winkleman Dome Field, Wyoming Despite its lack of some of the characteristics generally considered essential for a successful forward steam drive, this shallow reservoir, with its high saturation of viscous oil, has shown a gratifying response. Introduction The Winkleman Dome field in Fremont County, Wyo., was discovered in 1944 when the first well was completed in the Tensleep reservoir (Fig. 1). Early development in the field was exclusively in the Tensleep and Phosphoria reservoirs although the existence of oil in the shallower Nugget was recognized. Because of a lack of market and the low price of 14deg. API gravity crude, the Nugget could not be developed profitably. This situation was unchanged until crude prices increased by about 40cts/bbl in 1957. Five wells were drilled in 1958 and 1959 to obtain information about the reservoir, crude properties and primary performance. Studies indicated that none of primary performance. Studies indicated that none of the usual secondary recovery methods would be profitable. Even though the reservoir did not possess all profitable. Even though the reservoir did not possess all the criteria considered desirable for a steam injection project, it was believed that forward steam drive project, it was believed that forward steam drive should be tried. A steamflood was started in March, 1964, expanded in 1965, and expanded again in 1967 to the present area. The equipment used in these operations was discussed in an earlier paper. The purpose of this paper is to present performance of the Nugget reservoir during forward steam drive operations. Reservoir Characteristics Geology The Winkleman Dome field is an asymmetrical surface anticlinal feature along the northwest end of the Wind River basin of Wyoming. The accumulation of oil is primarily a result of structural relief. There is both surface and subsurface evidence of faults trending in a northeast-southwest direction. This faulting probably had a minor influence on the oil probably had a minor influence on the oil accumulation. (Within the presently developed acreage, only one fault in the northern portion has had any significant effect on well performance.) The Nugget sandstone is of Jurassic age and generally is considered to be a blanket sand. Within the Winkleman Dome field the formation is divided into three benches separated by shaly lenses. Fig. 2 shows a typical sonic log through the Nugget formation, with permeability also plotted to illustrate the zonation. The productive limits of the reservoir are determined by structural position. Oil-water contact was determined from information on Well 50, which appears to be located near it. Rock and Fluid Properties Average values for the various reservoir parameters are listed in Table 1. The rock properties are based on cores from five wells, three of which were cored with oil. The sand has excellent porosity and permeability (at least for a Rocky Mountain reservoir, permeability (at least for a Rocky Mountain reservoir, although these factors are not quite so good as those associated with steam recovery projects in some California fields). Pay thickness for the reservoir was developed from sonic logs correlated with core analysis data. Fluid properties were obtained from samples collected at the wellhead. The crude is a dead, viscous, 14 deg. API gravity oil. The original reservoir pressure was 210 psig. The primary producing mechanism was water influx. P. 35