Development of advanced enhanced oil recovery technologies, especially for “heavy oil,” to increase the recovery from known fields is critical for maintaining TAPS trough-put. Heavy oil is a dense, viscous type of crude oil with an API gravity between 10° and 20°. Generally, this oil has a viscosity between 100 and 10,000 centipoise, and does not flow readily in the reservoir without dilution and/or the introduction of heat. Particular emphasis needs to be placed on evaluating technologies that could help recover more of this underdeveloped heavy oil resource in Alaska. Advanced oil recovery technologies, such as miscibility enhanced CO2-EOR will be essential for recovering more from the largely undeveloped heavy oil resource.
Initial steps are being taken to produce a portion of the in-place oil resource from two large heavy oil reservoirs on the Alaska North Slope. The Schrader Bluff Formation in the Milne Point Unit has experienced a steady growth in heavy oil production, reaching 19,000 barrels per day in 2003, from a few thousand barrels per day in the 1990s. It is now producing about 12,000 barrels per day. The West Sak Formation in the Kuparuk River Unit, after years of experimentation and delay, produced 18,100 barrels of heavy oil per day in 2007. The Unit operator has submitted plans to the Department of Natural Resources, Alaska to conduct an aggressive program of horizontal well drilling and water injection to increase West Sak heavy oil production to a peak 26,000 barrels per day in 2015.
Further advances in heavy oil recovery technology, adapted particularly to the special geological, reservoir, environmental, and operational situations in Alaska, will be essential for increasing oil recovery from Alaska’s large heavy oil endowment. Current research supported by the NETL’s Arctic Energy Office includes:
Alaska’s Potential from unconventional sources:
Use of Polymers to Recover Viscous Oil
Alaska’s North Slope contains a very large unconventional oil resource—over 45 billion barrels of heavy/viscous oil. Production has been limited to pools in the core area that flow with thermal or miscible gas injection/water- alternating-gas, but the majority of the oil is stranded. The project will be valuable in establishing the most cost-effective path forward to develop Alaska heavy oil resources, studying both existing and new viscoelastic polymers to change the viscosity, new methods for improved injectivity during polymer injection, sweep efficiency enhancements, and effects of induced fracturing and formation parting.
Fluid and Rock Property Controls on Production and Seismic Monitoring Alaska Heavy Oils
A prime factor limiting the efficiency of heavy oil recovery is the heterogeneity of the system. Variability includes the heavy oil with varying resin and asphaltene contents and the rock matrices’ with different porosities, permeability, connectivity, and mineral content. Using seismic data, this study is attempting to characterize the reservoir fluid and rock properties such that a geophysical monitoring program can potentially be used to enhance heavy oil recovery.
Phase 2–Drilling and Production Testing the Methane Hydrate Resource Potential Associated with the Barrow Gas Fields
Previous research efforts funded by the DOE, supported the hypothesis that methane hydrates exist within the Barrow gas fields. Based on detailed reservoir modeling and other favorable conditions (i.e., formation gas composition, formation water chemistry, and reservoir pressure), it is believed that these accumulations may be interacting with the free gas reservoirs, providing pressure support through dissociation of the hydrates. During Phase 2 of the project, a production test well will be designed, drilled, logged, and cored, and a continuous reservoir surveillance and monitoring program will be implemented to prove the commercial potential of producing methane hydrate through depressurization dissociation from the gas zone underlying the hydrates.
Producing Light Oil from a Frozen Reservoir: Reservoir and Fluid Characterization of Umiat Field, National Petroleum Reserve, Alaska
The Umiat oil field contains light oil in a shallow, frozen reservoir and may be typical of an abundant supply across the Arctic permafrost. Most prior efforts researching how to produce in these strata of rock/ice/light oil system at low pressures has been focused upon techniques for heavy oil in unconsolidated but unfrozen sands or on gas hydrates. This research project is developing a robust reservoir model to test possible production methods for Umiat and similar frozen reservoirs that do not use steam or a liquid that will freeze.