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Contenuto archiviato il 2022-12-27

PECORADE EVALUATION OF RESULTS

Obiettivo

This project concerns the evaluation of the results from a CO2 injection in PECORADE reservoir which has been performed in 1983 ( contract TH 5044/82) to maintain the reservoir pressure above the critical pressure. It follows a feasibility study performed under contract TH 5029/81 and a CO2 injection under contract TH 5044/82
.
PHASE 1 - WATER INJECTION
At the end of the takeover operation of well PCE 13 (former CO2 injection well) in the upper bed B2, an injectivity test has provided relatively unsignificant results compared to the forecast, with about 500 bars at the wellhead for non-significant injection flowrates (July 1984).
After perforation cleaning production started (10 to 15 m3/d). This caused water drive to be postponed, but to respect the previsional schedule presented at the EEC, water injection was cancelled.
PHASE 2 - EVALUATION OF RESULTS CO2 PRODUCTION
Although early breakthroughs of CO2 and very short transit times were observed, only 10% of the CO2 injected was produced. There are two possible theories to explain the location of the remaining 90% within the reservoir.
Communication of fractures network during injection with the highly fissurized Northern zone forming the top of the reservoir. In this case, the CO2 very quickly migrated towards the gas cap without displacing much oil.
CO2 percolation into the matrix within and beyond the pilot zone. In this case, there is no gas front as is the case with a homogeneous circular radial sweep. The CO2 dissolved gradually in a large volume of oil, displacing this oil essentially by swelling action. Production of CO2, from PCE 13 and PCE 23 a year after ending the injection, the ingress of part of the CO2, into the drain and the absence of very high GORs are all factors in favour of this theory.
OIL PRODUCTION
The oil produced appears to have been slightly affected by the injection of CO2 and can be related directly to the effects of pressure caused by injecting water into PCE 18.
Extremely poor characteristics of the lower porous zone of B2, which turned out to have productivity and injectivity indices much poorer than had been suggested by the petrophysical analyses have led to the creation of widely extending fractures during injection and the impossibility to drain through the production wells of the pilot project.
However, when well PCE 13, which was intended as a water injection well, was placed on production, water drive had to be postponed and did not prove possible as part of the CO2 project (in order to comply with the schedule). This resulted in total and final shutdown of all the Pecorade storage and injection facilities. CONCLUSION
Implementation of CO2 injection at Pecorade has enabled mastering of the method, from elaboration of the fluid at the Lacq plant units until injection of carbon dioxide gas into the well. Whilst this objective can be considered by and large to have been reached, one specific point has not been solved so far, with repeated incidents of cracking of the hydraulic blocks of the CO2 injection pumps. The conclusion of the experts examining these blocks was that gradual fatigue cracking had occured, though without revealing any corrosive action.
The present project comprises the water sweeping of the injected CO2 to the production wells. Two phases were to be carried out:

Phase 1 - Water injection
Phase 2 - Evaluation of results

Invito a presentare proposte

Data not available

Meccanismo di finanziamento

DEM - Demonstration contracts

Coordinatore

GERTH
Contributo UE
Nessun dato
Indirizzo
232 AV. NAPOLEON BONAPARTE
92500 Rueil Malmaison
Francia

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Costo totale
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