Published by the DTI Oil & Gas Directorate for the reservoir engineering and IOR community in the UK.
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Design and Implementation of Field Trial of Microbial Enhanced Oil Recovery

David Hughes of Senergy Ltd describes a joint industry proposal to design and implement a UKCS field trial of microbial enhanced oil recovery. (The proposal was submitted to ACHARR, March 2002.) (david.hughes@senergyltd.com)

Background
Recently Statoil have developed the Norne field, in the Norwegian sector of the North Sea using an aerobic microbial enhanced oil recovery technique. Also there have been significant advances in various MEOR techniques in onshore application in North and South America and elsewhere since the technology was last assessed for UKCS application. Variations of the process target waterflood residual oil by producing a surfactant-like effect increasing microscopic sweep, or cause flow diversion of chase water by producing a blocking effect thereby improving the macroscopic sweep.

The objective is to identify and field trial a microbial enhanced oil recovery process based on the most suitable process currently available for offshore application in the UKCS.
The benefit for the participants is that the design, practicalities and potential of the offshore application of MEOR can be tested in a realistic scenario without any participant having to bear the full cost.


Figure shows potential benefit from MEOR process

Technical Overview
The project would be divided into two phases. Funding is being sought for Phase 1 which is to take the project as far as completion of the front end engineering design stage. Phase 2 would be the implementation of the trial.

The team involved would include a Project Manager, Facilities Engineer, Reservoir Engineer, Oilfield Chemist and Reservoir Microbiologist

Those participating oil companies that wish to, would put forward areas of their fields where potentially the trial could be carried out. These areas would be screened for their suitability for the trail. This would be undertaken by a series of engineering assessments and laboratory experiments using the disciplines noted above. Reservoir simulation models, including mechanistic models of the recovery mechanisms occurring during MEOR, would be built for the more likely potential trial areas and core flooding experiments relating to the two most likely candidate areas and processes would be performed. Also, if judged necessary, tracer studies would be undertaken in the two most likely trial areas.

Once the foremost candidate area and process has been identified, a front end engineering design (FEED) study for the trial would be undertaken. This would include designing the facilities required to add the microbes (if the process does not rely on indigenous microbes), air (if the process is aerobic), and nutrients to the injection water, and the building of a detailed engineering model of the trial area which honours process constraints. Pricing and sourcing the engineering facilities and injectants would also be undertaken.

The sorts of issues that would be investigated are, for example:

• Is the stimulation of indigenous microbial colonies (either those present on geological time or introduced with injection seawater) sufficient or do the populations need enhancing by the injection of microbes?
• If the process were aerobic would corrosion in the facilities and tubulars be an issue?
• What would be the implication of stopping injection of biocide if this is being used to control SRBs?
• What is the expected outcome of the trial, including the timing and extent of the anticipated effects?
• What quantities of nutrient are required?
• What mechanisms might occur that would lead to an increase in oil recovery?
• How would the success or other wise of the trial be judged?
• How will the baseline for the expected behaviour without the treatment be established?
• How far into the reservoir are the microbial colonies likely to grow and produce a beneficial effect?
• What are the logistical implications of transporting the quantities of nutrient required offshore?
• Are the proposed processes covered by patents?
• What are the commercial issues?
• What are the potential downsides of undertaking the trial?
• What is the overall cost of the trial?

Sponsors
The indicative price for Phase 1 is £340k spread over 18 months. It is anticipated that four sponsors would be required each paying £50k in the first year and £35k in the second year.

At a recent workshop on MEOR sponsored by the DTI Oil and Gas Directorate, a number of Operators and their partners indicated that UKCS trials of MEOR should be undertaken. Service companies that might benefit from the adoption of MEOR in the UKCS might also be potential sponsors.
The cost of Phase 2 would depend on the specifics of the field selected but the expected price would be in the range £200-450k.

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