Micellar/Polymer Flooding in the Bradford Field

Abstract

Summary This paper describes the development and operation of a 218-acre [88-ha] micellar/polymer flood in the Bradford field of Pennsylvania. A definite tertiary oil production response occurred after injection of 35% PV of micellar slug and polymer. A total of 191,226 bbl [30.4 × 10(3) m3], PV of micellar slug and polymer. A total of 191,226 bbl [30.4 × 10(3) m3], or 3.4 % PV, oil was produced, which was significantly less than predicted. The production response occurred later and was lower than expected, and operations were discontinued before the scheduled polymer-injection sequence was completed. Introduction Pennzoil Co. has been a significant oil producer in the Bradford Pennzoil Co. has been a significant oil producer in the Bradford field since 1889. Between 1889 and 1921 the company developed primary oil reserves and experimented with gas drive and limited primary oil reserves and experimented with gas drive and limited waterflooding. Waterflooding of company properties became an accepted and successful practice after 1929. In 1940, the Bingham leases, which are located in the southeastern lobe of the 90,000-acre [36 × 10(3)-ha] Bradford field (Fig. 1) and had produced primary oil since 1882, became the site of a large, successful waterflood. This was exemplified by an 816-acre [330-ha] five-spot development on the Bingham 533 lease, which produced 5.4 million bbl [860 × 10(3) m3] of waterflood oil between 1940 and 1980. An evaluation of the project area indicated a significant post-waterflood residual oil saturation (ROS) that was considered an attractive target for EOR. In 1968, efforts began to test the effectiveness of the Maraflood(TM) process to recover postwaterflood residual oil. The first of these field tests (Special Project 5) was a 3/4-acre [0.3-ha] pilot containing five producing wells and a single injection well drilled on an inverted five-spot pattern. This project operated from 1968 to 1970 and demonstrated that postwaterflood residual oil could be mobilized and produced by micellar/polymer flooding. On the basis of these encouraging results, a 47-acre [19-ha] expansion was developed in 1970. This project, referred to as Special Project 7, used the old waterflood pattern consisting of 3-acre [12-ha] five-spots and was conducted to evaluate the commercial potential of the Maraflood process. A significant tertiary response was seen, and between 1971 and 1981 the project produced 208,000 bbl [33 × 10(3) m3] oil, or 281 bbl/acre-ft [0.036 m3/m3]. Details of both the pilot and expansion have been previously reported. In 1980, approval was obtained for a self-certified tertiary recovery project under the U.S. DOE Front End Incentive Program. This test, referred to as Special Project 8, was located on the Bingham leases near Special Projects 5 and 7 and was developed to evaluate the recovery efficiency of the micellar/polymer process in the previously waterflooded Bradford Third sand on a commercial, previously waterflooded Bradford Third sand on a commercial, large-scale basis. Reservoir Description The Bradford Third sand is the major producing formation in the Bradford field. Average reservoir properties for the formation include 15% porosity, 10-md permeability, 1,800-ft [549-m] depth, a net sand thickness of 30 ft [9 m], and a postwaterflood ROS of 40%. Within the Bingham test area, the Bradford Third sand can be divided into three distinct layers, characterized as the upper, middle, and lower zones. The upper and lower zones display relatively low porosity and permeability (13% and 8 md, respectively). Two distinct regions of varying rock properties can be found within the middle zone and have been characterized as the middle-high and middle-low sand regions. The middle-high region exists as a uniform sand body throughout the project area with a net thickness of 6 to 25 ft [1.8 to 7.6 m] and an average porosity and permeability of 18% and 120 md, respectively. The lower section of permeability of 18% and 120 md, respectively. The lower section of the middle zone displays lower average porosity and permeability (13.8% and 22.7 md, respectively).