Objective
To optimize geothermal energy production in existing doublet by desulphurization of dogger water in La Courneuve doublet (North of Paris).
This new adaptation of special hydrocarbon technology to geothermal sector will be developed to maintain and improve reinjection performance allowing improved production. Electrochlorination will be used to neutralize bacteria activity and oxidize - H2S - to avoid iron sulphide precipitation and bacterial corrosion in injection wells of Dogger doublets.
2-3 m3/h of Dogger geothermal water extracted will be diverted from the main surface loop and treated before remixed with the 200 m3/h flowing water for injection. Concentration tests will permit optimization of the use of different chemical additives.
This project is successful from the technical point of view and could be used to treat geothermal water with low concentration of sulfides. At high concentration, the cost of the electricity needed to obtain a good chemical reaction is uneconomic and the emergence of secondary effects prevent the system to give a good efficiency.
During 1987, an important evolution of the knowledge of iron sulfides deposits in geothermal environnement has been reccorded.
To protect the casing of the existing doublets, several wells have been equiped with downhole inhibitors injection pipes. In these conditions the application of electrochlorination systems is not justified, considering an over cost of about 100 KF.
The place A destined for the dimensionement of the electrochlorisation unit concluded the neccesity to modify the objective of the phase B. In particular, the electrochlorisation system is developing secondary effects with penalizing costs when it is used to oxidize the dissolved sulfides present in a great quantity. On the other hand, it becomes acceptable as soon as the objective is to neutralize the bacteria activity and to oxidize sulfides. Before the settlement of the pilot, a new design of the unit has been realised.
The technical results are that the sulfides, present in trace, are immediately oxidized with the electroclhorization system.
The bacteria activity is neutralized with a very low intensity of chloration. No secondary effects has been noted during the test.
The average electrical power to realize the reaction is comprised between : 0,31 and 0,78 Kwh/m3 of treated geothermal water.
Topic(s)
Call for proposal
Data not availableFunding Scheme
DEM - Demonstration contractsCoordinator
45064 Orléans
France