Tertiary Recovery by the Maraflood Process in The Bradford Field

Abstract

Following an encouraging pilot test, a large-scale project using the Maraflood oil recovery process was initiated in the Bradford field. The expanded project used the old waterflood five-spot pattern, and a dramatic oil production response occurred. Field testing has shown that tertiary oil can be recovered by, the process from the previously waterflooded, oil-wet reservoir. Introduction Numerous laboratory tests have been conducted to study oil displacement with micellar solutions. These tests and certain field tests have demonstrated that additional oil can be recovered by using micellar slugs followed by thickened water solutions. In the Bradford field of Pennsylvania, where the waterflooding technique began, many different tertiary oil-recovery methods have been attempted with limited success. This paper presents the results of the first field project to successfully recover tertiary oil from the Bradford Third Sand reservoir. The performance of this test is evaluated and the operations are summarized. This project is testing the Maraflood oil-recovery process on leases of the Pennzoil Co., operator of the process on leases of the Pennzoil Co., operator of the test. Pennzoil is using the Maraflood process under license from the Marathon Oil Co. Process Description Process Description The process is a method of producing oil under both secondary and tertiary recovery conditions. Micellar solutions make up the first in a series of displacing fluid banks injected into an oil-bearing formation. When properly designed, these solutions can displace a high properly designed, these solutions can displace a high percentage of the residual oil in the reservoir. Micellar percentage of the residual oil in the reservoir. Micellar solutions contain primarily hydrocarbon, surfactant, and water. They are designed to be stable in the presence of reservoir fluids and rock. For maximum recovery efficiency, it is preferable that a slug of micellar solution has sufficient viscosity to give favorable mobility control with respect to reservoir fluids. A mobility buffer is injected to protect the recovery efficiency of the slug. The mobility buffer is a bank with mobility lower than the slug. Water solutions containing polymers normally are used as the mobility buffer. Water is then injected to drive the slug and the mobility buffer through the reservoir. Project Location and Reservoir Data Project Location and Reservoir Data Test Site The Bingham field test is located in the Bradford field in McKean County, Pa. The test includes a pilot and an expansion on the Bingham lease, situated on the southeastearn edge of the Bradford field. The 0.75-acre pilot test is located 500 ft southwest of the expansion. pilot test is located 500 ft southwest of the expansion. The expanded test consists of about 47 acres, using the original waterflood five-spot pattern with a well spacing of slightly less than 3 acres. Fig. 1 is a map showing the location of the test area within the Bradford field. Maps of the pilot and the expanded test pattern are shown in Figs. 2 and 3. The producing wells in the expansion are divided into two groups - Farms A and B. Farm A consists of about 26 acres with nine confined five-spots. The remaining 16 producing wells surround the pattern and make up Farm B. Three observation wells (Wells 109, 110, and 413) are located at points midway between injectors and producers. JPT P. 129