Objective
The object of the project was to evaluate the feasibility of increasing the recoverable reserves of the Emeraude field, offshore Congo, by injecting steam in the formation.
Indeed, after seven years of natural depletion development, the field had produced less than 2% of the oil in place, of a volume estimated at 860 Million tons. Tests relative to the injection of water in the structure turned out to be failures. As a direct consequence of the field nature, formed of compact silty layers and cracked lime layers playing the role of drains, this situation has impelled us to study steam injection.
The fragile feature of the problem, linked to the particularities of the field, namely:
- Shallowness making impossible the use of traditional drilling methods;
- Low pressures and fissuration of reservoirs requiring methods for fighting against mud and cement losses during operations;
- Poor consolidation of the silts;
- Offshore environments,
have led to the execution of a pilot study.
By the end of 1986, that is after 20 months of continuous steam injection, methods and installations designed within the scope of this project, proved to be very satisfactory :
- tilt rig drilling operations went out without problems
- fluid losses during drilling were limited thanks to colmating plugs
- cementations proved to be of good quality with minimum chafing behind casing
- long drive pumping units inclined at 30 degrees operated perfectly. And, the industrial utilisation of a numerical control system for the pumping parameters, which was a first, also proved successful. In very inclined wells, pumping rods showed important but non excessive wear at the coupling level
- the fabrication chain of steam from sea water (desalting units, boilers, compressors) operated at a rate of 75%, which is satisfactory considering the severe environment.
The pilot installations comprise :
- a drilling platform for 11 production or injection wells, with guide tubes inclined at 30 degrees for the deviated wells and production equipment.
- a utility platform linked to the first platform by a gangway and grouping two steam generators, two water desalting units and the utilities.
The project which aims at designing and optimizing these installations, comprises two phases :
PHASE 1 :
Basic engineering including studies on drilling, cementation, process, structures and on equipment for pumping, water desalting, steam generation, gas feed and transport.
PHASE 2 :
Detail engineering. Consultation and calls for tender relative to the equipment, the construction and the execution. Engineering works within this phase allowed to define and order the overall equipment required for the execution of the pilot. These tasks became reality with the installation of the main equipment.
- Tilt rig tests (January 1983)
- Installation of the drillimg platform and floor (August 1982)
- Installation of the utilities platform and deck (July 1983)
- Assembling of production and injection equipment (autumn 1983).
Programme(s)
Topic(s)
Call for proposal
Data not availableFunding Scheme
DEM - Demonstration contractsCoordinator
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