Objective
(1) check that the upper reservoir, of very low permeability, can be produced by carbon dioxide injection and (2) find out if the production of the nearly depleted lower reservoir can be extended economically by injecting carbon dioxide and nitrogen.
Phase I : Showed that, at bottom hole conditions, the miscibility oil/carbon dioxide is effective and that additional oil recovery by displacement could be satisfactory.
Phase II : The injection-production test in the same well shut down a few years before, has proved disappointing, probably due to the very low permeability of the upper reservoir.
Phase III : 2600 tons of carbon dioxide and 1800 tons of nitrogen were injected. Gas breakthrough occured from 10 weeks to 4 months after starting injection depending on the distance and location of producing wells.
A total of 1000 tons of incremental oil was produced over one year period.
This yields a ratio of 0.23 tons of additional oil per ton of gas injected.
This low ratio condemns any industrial development.
The pilot has also confirmed that extreme caution has to be used when planning to push a slug of CO2 with nitrogen.
The CO2 gets trapped in reservoir liquids due to its high solubility and one may end up with a nitrogen displacement front.
A high permeability streak was evidenced between the injector and one well outside the four producer pattern.
A new project called "testing a new method to improve sweeping by injection of foaming agent and nitrogen (Phase I)" (TH./05073/86) is under way.
Its aim is to attempt to block high permeability paths and thus increase matrix productivity.
The project is divided into three phases:
Phase i:
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Theoretical studies including a geological updating of the structure with emphasis on fracture system, a laboratory study on miscibility and fluids behaviour, a reservoir analysis based on production data and simulation.
Phase ii:
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Injectivity and production test in the upper reservoir of the same well.
Phase iii :
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Test the displacement efficiency and profitability with a four-spot pattern in the lower reservoir.
Programme(s)
Topic(s)
Call for proposal
Data not availableFunding Scheme
DEM - Demonstration contractsCoordinator
75116 PARIS
France