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New Life for an Aging
California Field
Warren Resources Inc. has embarked on an
active redevelopment program in the Wilmington Townlot Unit
(WTU) and adjacent North Wilmington Unit (NWU) in the
central part of supergiant Wilmington field. These
properties were originally unitized in 1973 by majors and,
like most of California's mature fields, are now in the
hands of an independent. Plans are to drill more than 500
wells in the next few years, targeting development in
several reservoirs. Drilling will be done from cellars,
which places wellheads and facilities below ground level.
Estimates are that the WTU has produced only 20% of the
estimated 727 million bbl of original oil-in-place, leaving
an average remaining recovery potential of 228,000 bbl/well.
Warren Resources estimates that WTU could yield another 92
million bbl of oil if the company were able to attain a 32%
recovery factor.
Warren Resources took
over operation of WTU in March 2005 and NWU at the end of
2005. The units produce oil mainly from the Upper Terminal
formation at 4,000 ft and the shallower Ranger and Tar
formations, all Tertiary in age. Since acquisition, the
company has hiked WTU production from 375 bopd to more than
2,100 bopd. This increase results from additional production
from new wells drilled and completed in the Upper Terminal,
Ranger and Tar formations. The strategy at WTU is to develop
seven-spot waterflood patterns in the Ranger and Upper
Terminal formations. NWU now produces close to 400 bopd.
Warren Resources has budgeted $68 million
(74% in WTU) in
2007 for drilling and infrastructure |
development. This includes 34 producing and injection
wells at WTU, and 14 new wells and 12 recompletions at NWU.
The company plans to construct as many as five doublewide
drilling cellars at WTU that can each accommodate two rows
of wells in open cement-lined trenches. A skid-mounted
drilling rig allows for rapid rig moves, and all fluid
production and clean water reinjection occurs at wellheads
in the cellars.
Tar formation horizontal wells: As of
early May, the company had drilled eight Tar formation
horizontals. The Tar formation was not previously exploited
with secondary recovery. The first horizontal completion,
which occurred in August 2006, had a 1,200 foot lateral and
initially produced some 150 bopd. Modern logs from
waterflood development drilling in the Upper Terminal
formation is helping Warren Resources identify additional
Tar formation wells. As of early May, the eight horizontal
wells were averaging 100 bopd with a water:oil ratio (WOR)
of 2, without any pressure maintenance. There are another 10
horizontal drilling locations already identified. Once the
initial group of horizontals is developed, the company will
evaluate the potential for additional horizontals, including
in other potentially productive sands.
Upper Terminal formation: As of May
2007, the new Upper Terminal wells are averaging about 25
bopd. Some Upper Terminal wells drilled in the north area of
the field have been below average production with very low
WORs. Effects of water injection support, which is not
evident yet, are expected within the next 12 to 24 months.
Ranger formation: Warren Resources drilled and completed
its third Ranger formation well in the 1st
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quarter of 2007. Currently, the Ranger wells are
producing an average of 40 BOPD with a WOR of 20. There are
plans for an additional 5-10 Ranger wells in 2007.
Excerpted from "Central Wilmington Oil Field Due for
Denser Development," Oil & Gas Journal, Feb. 19, 2007, pp.
36-37; and press releases (dated 10/2/06, 12/14/06, 5/4/07)
by Warren Resources. 
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Power
From
Stranded Gas Saving California Leases
A DOE-supported project (Oil Field
Flare Gas Electricity Systems or OFFGASES) is
demonstrating how distributed power generation from
stranded natural gas reduces power costs and is
making a difference in saving marginal leases.
Results from four field demos with fuels of varying
energy content/quality are demonstrating the
possibilities.
- High-Btu gas (1,600
Btu/scf): boosted oil production in its
three-well marginal oil field from 10 to 23 bopd.
- Medium-Btu gas (not meeting
pipeline quality requirements): now producing
150 bopd in a 19-well field that had been at
risk for abandonment.
- "Harsh" (contains naturally
high levels of N2, CO2, H2S) gas: brought into
compliance with air emissions regulations by
scrubbing hydrogen sulfide from the gas using a
patented sulfur-treating system.
- Ultralow-Btu (as little as 15
Btu/scf): Just to flare it, producers have to
spike it with purchased natural gas. Tests using
FlexEnergy's Flex-Microturbine, which uses
catalytic combustors, are ongoing. While the
microturbine is working, improvements are still
needed and testing continues.
View further information in DOE's
Techline online at
www.fe.doe.gov/
news/techlines/2007/07061-Creating_Energy_from_Waste_
Gas.html. |
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West
Coast
Region