Development History of Bell Creek Field, Powder River County, Montana

Abstract

HADDENHORST, FRED A., SAMUEL GARY OIL PRODUCER CASPER, WYO. MEMBER AIME Abstract The Bell Creek field, discovered in June, 1967, lies on the northeast flank of the Powder River basin in the south-east corner of Powder River County, Mont. Oil accumulation is the result of stratigraphic entrapment in multiple bars developed offshore from a river delta deposit. The sand averages 18 to 20 ft in thickness and 27 percent porosity throughout the most of the reservoir. Development has been rapid, and more than 315 producing wells have been drilled since active development started in Aug., 1967. Drilling is rapid and relatively simple, as are completions. Initial potentials vary from less than 300 to more than 1,500 BOPD and average about 450 BOPD. Primary reserves will average 250,000 bbl/well or about Primary reserves will average 250,000 bbl/well or about 75 million bbl for the field. Secondary reserves should equal or exceed primary reserves. Four pipelines presently are taking approximately 55,000 B/D from the field with peak rate of 60,000 B/D expected by mid-summer, 1968. peak rate of 60,000 B/D expected by mid-summer, 1968. Contract has been let for a two-product gasoline plant capable of handling 22 MMcf/D; completion is scheduled for fall, 1968. The gathering system will be low pressure. Fuel gas will be returned to the leases an the remainder sold to Montana Dakota Utilities. The most serious operating problems at present are paraffin buildup in flow lines problems at present are paraffin buildup in flow lines and sand production; both problems vary in severity throughout the field. Introduction The Bell Creek field has proved that the Muddy sand in the Powder River basin frequently is an excellent reservoir with outstanding production capabilities and economics. These qualities, as exhibited at Bell Creek, have had an electrifying effect upon wildcat and development drilling in the area. Since discovery, 53 Muddy wildcats have been drilled in the general area. Active development drilling started in Aug. 1967; over 315 wells have been drilled since that time. Pipeline construction started in Sept. 1967, and by mid March, 1968, four pipelines were handling over 40,000 BOPD. Thus in approximately 9 months, operators in this area have invested in excess of $30 million in field development and crude oil transporting facilities. Geologic Discussion The Bell Creek field is located in the southeast corner of Powder River County, Mont. 7 miles north of the Wyoming Powder River County, Mont. 7 miles north of the Wyoming state line. The field lies on the northeast flank of the Powder River basin, adjacent to the northwest margin of Powder River basin, adjacent to the northwest margin of the Black Hills uplift (Fig. 1). The first commercial Muddy sandstone oil production in Montana was found at Ranch Creek, 5 miles southwest of Bell Creek, in Sept. 1965. Fig. 2 shows the relationship of the Bell Creek field to Ranch Creek. Black, Bank, and Rocky Point oil and gas fields. Two types of logs are shown on Fig. 2 one from the Bell Creek field and one from the Black Bank field. The producing and at Bell Creek is developed in the upper Muddy zone, and oil accumulation is the result of stratigraphic entrapment by an updip pinchout. Fig. 3 is a structure contour map on top of the Muddy sandstone, and shows regional northwest dip at the rate of 100 ft/mile. The minor irregularities in structure are due to thickness changes in the Muddy interval. The trapping mechanism is a convex updip sand pinchout. The Bell Creek field has a northeast trend parallel to the northeast structural strike. JPT p. 787