Norge Unit Plan Implemented

PUBLICATIONS RIGHTS RESERVED PUBLICATIONS RIGHTS RESERVED Permission to include this paper in the Proceedings for the 1977 Permission to include this paper in the Proceedings for the 1977 Oklahoma City Section Regional Meeting of the Society of Petroleum Engineers, held in Oklahoma City, February 21–21, 1977, was secured from PETROLEUM ENGINEERS, where it was first published in the November, 1976 issue. Permission to copy is restricted. The paper is subject to correction. Abstract The engineering and planning activities preceding and following unitization of the preceding and following unitization of the Norge Marchand Unit in Grady County, Okla., are described herein. The 12,000-acre, 75-tract unit was approved by the Oklahoma Corporation Commission in Feb. 1974, 3 years after the discovery of the field. The unit area contained 75 wells developed on 160-acre spacing and producing from the Marchand sand at a depth of 10,100 to 10,800 ft. Sixty percent of the ultimate primary reserves had been produced prior to unitization. The plan of operation was designed to maintain reservoir pressure at or near the bubble-point pressure of the reservoir fluid by water injection. The project was expected to increase recoverable reserves by 31,750,000 bbl of oil. This represents an increase in ultimate recovery from 15.7 percent of the original oil in place by primary depletion to 32.5 percent. Reservoir pressure had declined below the bubble-point pressure of 2,826 psi to 2,405 psi when water injection commenced. Water psi when water injection commenced. Water injection volume has been equivalent to 4.6 percent of the pore volume, or 50 percent of percent of the pore volume, or 50 percent of the required fill-up volume. No severe channeling or water breakthrough has occurred. Producing GOR's have been reduced substantially Producing GOR's have been reduced substantially and reservoir pressure has increased. The designed injection rate of 35,000 BWPD has been achieved in 23 input wells. A suitable injection to voidage ratio has been maintained throughout the field. A planned eight-well infill development program is in progress to restore some of the productive progress to restore some of the productive capacity lost by injection well conversions. An adequate water supply of desirable quality has been developed and water injectivity has matched predictions closely. Introduction Concentrated engineering and planning efforts by 17 oil operators, representing 60 working interest owners and 344 royalty owners, culminated in the unitization of the 12,000-acre Norge Marchand Unit in Grady County, Okla., within 3 years after discovery of the field. By order of the Oklahoma Corporation Commission dated Feb. 19, 1974, the project was authorized for the purpose of pressure maintenance by water injection, which was expected to increase the recoverable reserves by 31,750,000 bbl of oil. Sun Oil Co. was named unit operator.