Optimization of a Mature Waterflood in the Long Beach Unit: Government and industry Joint Venture

Abstract

SPE Members Abstract The Long Beach Unit with 3 billion bbls of oil originally in place, is a part of the giant Wilmington Oil Field, the 4th largest field in the United States. In 1989, ARCO approached the City of Long Beach and State of California with a proposal to provide technology and capital needed to redevelop the field. The optimized waterflood program (OWP) agreement took effect on January 1, 1992 and today the LBU is producing more than 25% above the oil rate predicted from the base case decline. In addition, substantial reductions in both drilling and operating costs have been achieved. This paper discusses all aspects of the OWP agreement, including negotiations, technical studies, implementation, management philosophy and critical keys to success. Introduction The Wilmington Field, discovered in 1936, is largest field in the Los Angeles Basin shown in Figure 1. The Long Beach Unit (LBU) comprises the eastern portion of the field underlying the City of Long Beach and California coastal waters (Figure 2) in 30 ft of water. LBU production began in 1965 using directionally drilled wells from four man-made gravel islands and an onshore drill site located in the Port of Long Beach (Figure 2). Waterflooding was implemented at field start-up to improve recovery and prevent subsidence which was observed in older portions of the Wilmington Field during the 1950's. LBU production peaked in 1969 at 148,000 BOPD Current production is 46,000 BOPD and 557,000 BWPD from 640 active producing - wells using electrical submersible pump (ESP) as the primary artificial lift method. Gravel packs are required for unconsolidated sand control. Waterflood patterns vary by zone and area with 340 injection wells used in peripheral, line-drive, 5- spot, and inverted 7-spot patterns. Cumulative production to date is 800 million bbls oil (27% of original oil in place). Unit Operator is the City of Long Beach (City) through it's Department of Oil Properties. The City acts as trustee for the State of California (State), which receives the majority of Unit profits. Daily field operations are managed by THUMS Long Beach Company (THUMS), under the direction of the City. THUMS, now owned by ARCO, was originally a consortium of Texaco, Humble [Exxon], Unocal, Mobil, and Shell. The roles of the City as Unit Operator and THUMS as field contractor continue today as they did before the optimized waterflood program. GEOLOGY The Wimington structure is an asymmetrical anticline. Oil production is from lower Pliocene and upper Miocene rocks from 3000 to 7000 ft in depth. P. 241