DE-FE0005958

Goal
The goal of this project is to demonstrate the ease of use and potential of carbon dioxide (CO₂) injection/ production profile modifications using Silica Polymer Initiator (SPI)-CO₂ gel systems. The objective is to advance SPI-CO₂ Enhanced Oil Recovery (EOR) gel technology by performing multiple small- scale, field injectivity tests using both ‘Huff & Puff’ and conventional pattern flood applications. A sub-objective of the project is to improve the SPI-CO₂ gel integrity by testing a Super Absorbent Polymer (SAP) instead of the polyacrylamide (PAM) currently being used.

Performers
Impact Technologies LLC, Tulsa, OK 74135-6612
Clean Tech Innovations LLC

Background
Issues associated with using CO₂ for EOR are its low density and viscosity compared to the crude oil and brine in the reservoir. The injected CO₂ has substantially higher mobility relative to the crude oil and brine, which promotes "fingering" and early breakthrough of the CO₂ to the production wells. High conformance or sweep efficiency (i.e., good contact with all the crude oil in the reservoir) is particularly critical in costlier CO₂ floods where the end result of poor sweep efficiency is less oil recovered with substantially higher costs resulting from multiple handling (production, compression, and reinjection) of the CO₂.

Serious research has gone into developing gels for the primary CO₂ phase, but none are low cost and commercial. A unique, state-of-the-art SPI gel system currently offers a promising solution to the conformance problem with CO₂ floods. Of particular importance to this and other CO₂ injection projects is the use of an external initiator such as CO₂. In SPI-CO₂ gels, the CO₂ becomes the external initiator of the SPI fluid following its placement in the reservoir. An SPI mix slug will be incorporated in the water cycle of a Water Alternating Gas (WAG) injection and the CO₂ slug that follows will "finger" through and permeate the more viscous aqueous SPI mixture in the flow path, generating carbonic acid, which will immediately initiate the gelation process. This newly set SPI gel will divert the CO₂ that follows and cause it to finger and dissolve into fresh SPI mix, causing SPI gel to form at another locale. This process will continue until the CO₂ is fully blocked or all the SPI mix is consumed.

Impact
The SPI gel will improve sweep efficiency to a greater degree than conventional systems because it sets up in the high permeability paths that had been travelled previously by the CO₂ and is unique in that it is silicate based and will remain a low viscosity fluid until gel initiation is triggered by CO₂. This is a clear improvement over current technology where the gel gradually sets up as a function of time, regardless of location. In addition, the final product in commercial quantities is expected to be less expensive than competing polymer gels or other systems.

U.S. CO₂ EOR production has grown by 4 percent/year over the last 20 years to today’s level of 280,000 barrels of oil per day. The use of SPI gels is anticipated to further improve those levels by 1 percent/year within a few years of a successful demonstration and up to 3 percent/year in future years. SPI could add over 300 million barrels of otherwise bypassed reserves over ten years.

Accomplishments
The Principal Investigator has been in contact with major CO₂ flood operators to ascertain their needs and to inquire about performing tests in their fields. Several industry contacts have indicated that SPI gels have a place in the CO₂ market if the gels perform as expected during the project’s field test. Legal agreements are being pursued with two companies and one company has provided the project team with field data, fluids, and core segments for use and analysis. One major CO₂ flood operator wants to get to the field right away, while other operating companies have expressed interest.

The CTI lab performed over 600 gel forming bench tests, half at room temperature (74°F) and half at 140°F. Approximately 40 additives have been evaluated to date at various concentrations and combination with additional additives. Three formulations look very promising as candidates for further sand pack testing.

The base SPI polyacrylamide polymer was changed to a much easier to hydrolyze ultra-high molecular weight polymer. This has benefits of easier mixing in the field and better isolation of the SPI mix within high permeability zones, a key interest of the industry.

A full CO₂ capable sand pack system was developed at the CTI laboratory in Bartlesville, Oklahoma. Operational improvements to the modified sand pack system have been completed allowing the use of supercritical CO₂ at 1500 psi. These improvements include:

• Safe handling and discharging of carbon dioxide,
• Accurate means to meter and deliver supercritical carbon dioxide to core apparatus for sand pack testing, and
• Accurate means to meter and account for all gas and liquid mass exiting the system, and other improvements to aid in closing a mass balance (a 2% mass balance closure is anticipated).

The following equipment was purchased: four 5025 gallon Norwesco tanks; three 2500 psi positive displacement HydraCell metering pumps with Variable Frequency Controllers for the silicate and buffers; three Roper gear pumps for premixing of the polymer, transfers and offloading chemicals from delivery tanker trucks; four UET inline static mixers; and one full-stream Hoffer Flow Controls turbine flow meter.

Current Status (January 2012)
Impact Technologies is continuing to communicate with chemical providers and CO₂ operators on a frequent basis with the goal of securing multiple CO₂ flood operators for field testing of the SPI gel. By early 2012, in conjunction with the transition of the project into the next Phase/Budget Period, Impact Technologies plans to begin ordering the required chemicals necessary to complete testing and begin treatments in selected fields.

Test plans for field activity will be developed and include: preparation of the well and site for the field injectivity test (i.e. roads to the well site must be accessible); access to electricity to the site must be made available, unless generation is anticipated and desired; finalization of legal documents (liability releases, safety training, data releases) before moving onto the site; obtaining injection well and offset well data (oil rates, water rates, CO₂ rates, pressures, profile surveys, tracer surveys) to establish a pre-test base line; ordering and delivery of pumps, rate/ pressure recording and metering equipment to the field site.

Project Start: October 1 2010
Project End: January 31, 2014

DOE Contribution: $1,200,000
Performer Contribution: $300,000

Contact Information:
NETL – William Fincham (william.fincham@netl.doe.gov or 304-285-4268)
Impact Technologies – Kenneth Oglesby (kdo2@impact2u.com or 918-627-8035)
If you are unable to reach the above personnel, please contact the content manager.