The Bureau is seeking an operator to host this experiment within the operator’s Frio or Woodbine fields. The experiment

• Requires 4 to 5 depleted wells that are accessible
  
  
• Will involve the injection of CO₂ into one depleted well, using the remaining wells for monitoring purposes
  
  
• Is revenue neutral for the operator
  
  
• Could be designed to provide substantive auxiliary benefits for production

PROPOSAL

Injection and Monitoring Pilot, Phase III: Optimal Geologic Environments for Carbon Dioxide Disposal in Texas

Summary
The Bureau of Economic Geology is seeking an operating partner for a small pilot experiment to evaluate the costs and feasibility of geologic sequestration (underground storing) of carbon dioxide (CO₂). Although CO₂ is commonly injected into the subsurface for purposes of enhanced oil recovery (EOR), no substantive studies have evaluated whether the gas is effectively retained within the injection horizon. This experiment is an outstanding opportunity to participate at the critical implementation stage of a fully funded DOE effort to study geologic sequestration.

Background
The Bureau has been investigating the costs, feasibility, and risks of storing geologic sequestration (go to http://www.beg.utexas.edu/environqlty/co201.htm). This method has several technical and policy advantages over other emissions reduction options, including (1) extensive industrial experience, (2) long residence times, and (3) compatibility with the current U.S. energy profile.

The Bureau is designing an experiment to document the safety and effectiveness of injecting CO₂ into a high-water-cut, high-porosity sandstone formation and monitoring gas dissemination through tracer and geophysical methods. This experiment would document whether the use of such well-known activities as injection of CO₂ for EOR and disposal of wastes via deep well injection are viable in large-volume high-water-cut formations. The Bureau is seeking operators interested in participating in this experiment. Such a project would be revenue-neutral to a producer (DOE requires no matching funds) and could be designed so that auxiliary benefits to production could be substantive.

Project Work
The test site will be a field producing from a representative Gulf Coast or East Texas sandstone, such as the Frio or Woodbine, as many CO₂ emission sites overlie these rock types and do not have an extensive history of EOR. A small volume of dried, pressurized CO₂ will be trucked in and injected into a high-water-saturation interval of an existing well. Adjacent completions in the same reservoir interval, as well as completions in an overlying interval, will be monitored for dissolved- and gas-phase CO₂ breakthrough and concentrations of specifically designed chemical tracers injected with the CO₂. Geophysical tools will be used to track the movement of increased gas saturations. The experiment will differ from EOR and deep-well injection in that we will attempt to account for the fate of the injected CO₂.

Operator Benefits
DOE-funded activity in the field could prolong field life and may facilitate future use of watered-out acreage for CO₂ sequestration or deep-well injection, thereby providing an additional revenue stream.

Characterization of the injection and overlying intervals by the BEG will provide the operator with improved reservoir insight that could lead to more efficient management strategies. Economic and engineering information collected could be used to evaluate the feasibility of CO₂ EOR or repressurization of mature gas reservoirs to improve ultimate recovery. A successful project could have a positive influence on national policy.

Environmental Considerations
There are both environmental benefits and potential concerns associated with the proposed pilot experiment. Willingness to participate can be viewed as evidence of a company’s environmental stewardship and could place it in position for a major role if large-scale sequestration is eventually implemented. Although potential environmental concerns are associated with the leakage of injected gases to the surface, these concerns are neutralized by the fact that the injection will be intensively monitored and would cease if any significant leakage from the injection horizon occurred.