The Courtenay polymer flooding test is being completed, using a larger than usual slug size ; a special attention was given to monitoring the concentration and quality of the effluents.
The test is implemented on a ten acres inverted five spot in the center of the field of Courtenay, which is part of the Chateaurenard field. A rather large slug of partially hydrolized polyacrylamide was injected, consisting of 42% pore volume of a 1000 ppm active polymer concentration solution followed by a 39% pore volume solution at a tapered concentration.
By matching the oil cuts and polymer concentrations in the effluents of the producing wells we estimate that the producing wells we estimate that the adsorption of the polymer on the rock was 35 mug/g of rock.
Concentrations and main characteristics of produced polymer at the wellhead were produced polymer at the wellhead were determined using a sampling and separation methodology which prevents chemical and mechanical degradation. An increase in polymer molecular weight versus time has polymer molecular weight versus time has been observed, this polymer is not harmed by flow in the reservoir.
Three tests have been implemented in the Chateaurenard field before the Courtenay test :
A large polymer pilot (ref-1), on a 7 spot configuration, with one injector in the center and 6 producers at a distance of 400 m. A horizontal well, which extends 341 m inside the reservoir, was drilled in the northern edge of the pattern in 1985. The pore volume is about 800 000 M. Altogether a total of 280 000 m of polymer solution has been injected, polymer solution has been injected, followed by 410 000 ma of chase water. Total oil production is 86 000 M, of which 29 500 M is considered as tertiary oil.
A research microemulsion pilot, which was run on a small 100 m spacing inverted five spot (ref. 2 and 3). The injection of a microemulsion composed of high molecular weight sulfonates and C4-C5 alcohols started in 1978. It was displaced by a viscous polymer solution. Definite oil banks were observed on 3 of the 4 producing wells. We estimate that 70% of producing wells. We estimate that 70% of the oil in place in the swept areas has been produced.
An industrial microemulsion pilot (ref. 4 and 5). The pilot, which is nearing completion, is an extension on a large spacing, with an economically designed microemulsion, of the former pilot.
The pilot pattern is composed of four adjacent inverted five spots, distance between producers is 280 m (913 ft)- The volume of the micellar system was 3.5% of the enclosed pore volume (224 000 m)- 40% PV of a partially hydrolized PV of a partially hydrolized polyacrylamide solution concentrated at polyacrylamide solution concentrated at 1700 ppm was injected followed by the same volume with a tapered concentration and then chase water. The total injected volume was 247 000 M or 110% pore volume.