Subsidence In The Wilmington Oil Field, Long Beach, California, Usa

Subsidence due to Fluid Withdrawal. Developments in Petroleum Science, 41

edited by G.V. Chilingarian, E.C. Donaldson and T.E Yen 9 1995 Elsevier Science B.V. All rights reserved

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Chapter 6
SUBSIDENCE IN THE WILMINGTON OIL FIELD, LONG BEACH, CALIFORNIA, USA
X E N O P H O N C. C O L A Z A S and R I C H A R D W. S T R E H L E

INTRODUCTION

The Wilmington Oil Field is locatedapproximately twenty miles south of downtown Los Angeles, California in the Wilmington-Long Beach Harbor area. The field is one of a chain of oil fields that overlie a basement high extending for approximately 21 miles in a southeasterly direction from the Torrance Oil Field to the Huntington Beach Offshore pool (Fig. 6-1).

Fig. 6-1. Location map of Los Angeles Basin oil fields.

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X.C.COLAZAS AND R.W. STREHLE

With respect to cumulative and ultimate oil production, the Wilmington Oil Field is the largest field in California and one of the largest in the United States. The Wilmington Oil Field was officially discovered in 1931, but intensive development did not begin until 1936. By 1951, yearly production was more than fifty million barrels of oil, along with about 53,000 MMcf ofgas. By 1965, approximately 3500 wells had produced about one billion barrels of oil from 7825 acres. Until 1965, production was confined to the western portion of the Wilmington Oil Field. With the successful solution to the subsidence problem in this portion, development was started in the eastern portion (Long Beach Unit) which extends east of the harbor area in the City of Long Beach. Fromits discovery in 1931 to the end of 1990, more than 2.34 billion barrels of oil and 1.1 billion Mcf of gas have been produced from the Wilmington Oil Field. Current production is about 71,000 barrels of oil per day and 1,081,000 barrels of water per day. Remaining reserves for the field are approximately 600 million barrels. There are approximately 3100 injection and production wells. Since theearly 1940's the Wilmington Oil Field has been plagued by an unusually large amount of land subsidence. This was an especially critical problem because the field is located under the Long Beach and Los Angeles Harbor areas. The City of Long Beach, U.S. Navy, and Southern California Edison Company engaged qualified engineers, geologists and soil experts to investigate the causes and assist in finding asolution to the potential destruction of the industrial, port and naval facilities within the area of subsidence. They concluded that restoration and maintenance of subsurface pressures by water injection would prevent further subsidence. The result is one of the largest waterflooding programs in the world. Current field injection is in excess of 1.2 million barrels per day into 700 injectionwells. With this program in effect, subsidence was stopped. In the areas of maximum repressuring the surface has rebounded over one foot of the lost elevation.

GEOLOGY

General

The Wilmington Oil Field lies along the center of the southern margin of the Los Angeles Basin. This great depositional basin is bounded on the southwest by the Palos Verdes Hills and the Pacific Ocean, on the northand northeast by the Sierra Madre and Santa Monica Mountains, on the east by the Santa Ana Mountains and on the west by the Pacific Ocean. The entire area of the field is one of low topographic relief and provides no surface indications of underlying geological conditions. A study of the electric logs and cores of the oil wells provides a wealth of subsurface information regarding the structure andthe lithologic character of the sediments.

SUBSIDENCE IN THE WILMINGTON OIL FIELD, LONG BEACH, CALIFORNIA, USA

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Stratigraphy
The geology and stratigraphy of the field have been described extensively by Mayuga (1970), Truex (1972, 1974) Yeats (1973), Wilcox et al. (1973), Randell et al. (1983), Clarke (1987), and Henderson (1987). The following is supplied as a summary of this...