The project goal is to demonstrate that the alkaline-surfactant-polymer (ASP) technology can produce economic incremental oil from a reservoir containing a highly viscous crude oil.

Arnell Oil Company
Littleton, CO

Surtek, Inc.
Golden, CO

In 1919, oil was discovered in a lower horizon of the Crow Mountain Sand at a depth of 1,400-1,500 feet. The nominal water drive has been depleted for many years, and the average oil cut of the field now hovers at 7-8%. Current production for the field is about 100 barrels of oil per day. However, remaining oil in place at Poison Spider Field is estimated to be at least 14 million barrels. Therefore, the question is how to optimally produce the balance of the field's oil.

A pilot waterflood has existed in the southeast corner of the field since 1961. Due to the viscosity of the oil, the effects were positive but not dramatic. Production near the injection site experienced diminishing returns after a few years. ASP technology offers the promise of getting more oil into solution and creating a better bank of oil, resulting in sustained levels of higher production.

Project Results
Interfacial tension and phase behavior work suggested ASP flooding has potential for a highly viscous (150-300 cp) reservoir. A number of ASP solutions were formulated that provided sufficient interfacial tension reductions of more than 10,000-fold and optimum phase behavior to mobilize waterflood residual oil, based on capillary number theory. Mobility ratios of up to 8.6, low absorption of ASP components, and incremental oil recovery of up to 18.1% original-oil-in-place (OOIP) indicated that ASP flooding is a viable technology to produce more of this type of oil from this reservoir.

Benefits
The Poison Spider field produces a viscous, 22 degree API gravity black oil from the Crow Mountain Sand of the Lower Sundance Formation. Sour asphaltic crude oil, similar to that tested here, is the dominant oil type currently produced throughout the Rocky Mountain Region. While all reservoirs have unique aspects, the sampled strata of the Crow Mountain Sand reflected relatively typical characteristics with fair to good porosity and permeability. It is a mature reservoir relying solely on gravity drainage for drive.

The direct benefit from this project is that ASP flooding may result in at least an additional 2,500,000 barrels of oil from Poison Spider Field. More importantly, however, ASP technology is still relatively new and there are countless potential applications in mature fields with sour black crude oil throughout the U.S. The benefit of documenting the feasibility of ASP, under these conditions, will be to expose small independent operators to the potential of enhancing production. Further, this study will provide a quantitative foundation upon which operators can begin their particular evaluation.

Project Summary
The project demonstrated that:

• The reservoir was not sensitive to either NaOH or Na2CO3, and both were capable of supporting interfacial tension reductions greater than 10,000-fold.
• Water injection alone recovered an average of 53% OOIP, while ASP recovered up to 81.2% OOIP.

The project has been completed with the exception of a presentation at the 2006 SPE annual technical conference.

Publication
Final Technical Progress Report, December 2004.

$100,000

$122,278 (55% of total)

NETL - Virginia Weyland (Virginia.weyland@netl.doe.gov or 918-699-2041)
Arnell - Doug Arnell (Daarnell@comcast.net or 303-888-0082)