Page 289 - Introduction to Petroleum Engineering

PERFORMANCE OF CONVENTIONAL OIL AND GAS RESERVOIRS 277
14.3.1 Wilmington Field, California: Immiscible Displacement by
Water Flooding
A water flood uses injection wells to inject water into a reservoir. The injected water
provides pressure support and can displace oil. A pattern water flood uses injection and
production wells in a repeating pattern. The performance of the Wilmington Field in
California (see Figure 14.3) illustrates immiscible displacement by water flooding.
The Wilmington Field is in the Los Angeles Basin and was discovered in 1932 as
part of the development of the Torrance field. The Wilmington Field was first recog‑
nized as a separate field in 1936. The field is a northwest to southeast trending
anticline that is approximately 13 mi. long and 3 mi. wide. It is crosscut into fault
blocks that are vertically separated by normal faults that are perpendicular to the
long axis of the anticline. The southeastern part of the field is beneath Long Beach
Harbor and is called the Long Beach Unit (LBU). Otott and Clark (1996) reported
that the Wilmington Field contained approximately 8.8 billion barrels of original
oil in place (OOIP). The OOIP of the LBU of the Wilmington Field is greater than
3 billion barrels.
Seven stratigraphic zones have been identified between 2000 and 7500 ft true
vertical depth subsea (TVDSS). From shallowest to deepest, the zones are the Tar,
Ranger, Upper Terminal, Lower Terminal, Union Pacific, Ford, and “237.” An uncon‑
formity lies above the Tar zone and another unconformity lies below the “237” zone.
The zones and some fault blocks are sketched in Figure 14.4 (Fanchi et al., 1983;
Clarke and Phillips, 2003).
The upper six zones consist of unconsolidated to poorly consolidated sandstones
interbedded with shales and exhibit high compaction characteristics. Surface
subsidence up to 29 ft was observed as a result of producing the onshore part of the

North California

Pacific Torrance
Ocean

Los Angeles
Basin

Wilmington Field
Belmont
Offshore

FIgURE 14.3 Wilmington Field, California.