O

ir p

Chevron (Acheson, 1 "AGI site, 1989)

West Coast (Largest AGI site, 2002)

Batteile (Saline Experiment)

Statoil (Sleipner)

EnCana (Weyburn)

Amerada Hess (Seminole)

Altura (Wasson

Figure 5.22 Comparison of the magnitude of CO2 injection activities illustrating that the storage operations from a typical 500-MW coal plant will be the same order of magnitude as existing CO2 injection operations (after Heinrich et al., 2003).

Chevron (Acheson, 1 "AGI site, 1989)

West Coast (Largest AGI site, 2002)

Batteile (Saline Experiment)

Statoil (Sleipner)

EnCana (Weyburn)

Amerada Hess (Seminole)

Altura (Wasson

Figure 5.22 Comparison of the magnitude of CO2 injection activities illustrating that the storage operations from a typical 500-MW coal plant will be the same order of magnitude as existing CO2 injection operations (after Heinrich et al., 2003).

for industrial waste-water injection wells, injection pressure must not exceed fracture initiation or propagation pressures in the injection formation (USEPA, 1994). For oil and gas field injection wells, injection pressures must not exceed those that would initiate or propagate fractures in the confining units. In the United States, each state has been delegated authority to establish maximum injection pressures. Until the 1990s, many states set state-wide standards for maximum injection pressures; values ranged from 13 to18 kPa m-1. More recently, regulations have changed to require site-specific tests to establish maximum injection pressure gradients. Practical experience in the USEPA's Underground Injection Control Program has shown that fracture pressures range from 11 to 21 kPa m-1.

5.5.4 Field operations and surface facilities

Injection rates for selected current CO2 storage projects in EOR and acid gas injection are compared in Figure 5.22. As indicated, the amount of CO2 injected from a 500-MW coal-fired power plant would fall within the range of existing experience of CO2 injection operations for EOR. These examples therefore offer a great deal of insight as to how a geological storage regime might evolve, operate and be managed safely and effectively.

CO2-EOR operations fall into one of three groups (Jarrell et al, 2002):

• Reservoir management - what to inject, how fast to inject, how much to inject, how to manage water-alternating-gas (WAG), how to maximize sweep efficiency and so on;

• Well management - producing method and remedial work, including selection of workovers, chemical treatment and CO2 breakthrough;

• Facility management - reinjection plant, separation, metering, corrosion control and facility organization.

Typically, CO2 is transported from its source to an EOR site through a pipeline and is then injected into the reservoir through an injection well, usually after compression. Before entering the compressor, a suction scrubber will remove any residual liquids present in the CO2 stream. In EOR operations, CO2 produced from the production well along with oil and water is separated and then injected back through the injection well.

The field application of CO2-ECBM technology is broadly similar to that of EOR operations. Carbon dioxide is transported to the CBM field and injected in the coal seam through dedicated injection wells. At the production well, coal-seam gas and formation water is lifted to the surface by electric pumps.

According to Jarrell et al. (2002), surface facilities for CO2-EOR projects include:

• Production systems-fluid separation, gas gathering, production satellite, liquid gathering, central battery, field compression and emergency shutdown systems;

• Injection systems-gas repressurization, water injection and CO2 distribution systems;

• Gas processing systems-gas processing plant, H2S removal systems and sulphur recovery and disposal systems.

Jarrell et al. (2002) point out that CO2 facilities are similar to those used in conventional facilities such as for waterfloods. Differences result from the effects of multiphase flow, selection of different materials and the higher pressure that must be handled. The CO2 field operation setup for the Weyburn Field is shown in Figure 5.23.

It is common to use existing facilities for new CO2 projects to reduce capital costs, although physical restrictions are always present. Starting a CO2 flood in an old oil field can affect almost every process and facility (Jarrell et al., 2002); for example, (1) the presence of CO2 makes the produced water much more corrosive; (2) makeup water from new sources may interact with formation water to create new problems with scale or corrosion; (3) a CO2 flood may cause paraffins and asphaltenes to precipitate out of the oil, which can cause plugging and emulsion problems; and (4) the potentially dramatic increase in production caused by the flood could cause more formation fines to be entrained in the oil, potentially causing plugging, erosion and processing problems.

Was this article helpful?

0 0
Guide to Alternative Fuels

Guide to Alternative Fuels

Your Alternative Fuel Solution for Saving Money, Reducing Oil Dependency, and Helping the Planet. Ethanol is an alternative to gasoline. The use of ethanol has been demonstrated to reduce greenhouse emissions slightly as compared to gasoline. Through this ebook, you are going to learn what you will need to know why choosing an alternative fuel may benefit you and your future.

Get My Free Ebook


Post a comment