Coreflood testing

Coreflood Test Procedure. Laboratory coreflood experiments were performed to test the effectiveness of emulsion blocking in improving sweep efficiency at elevated temperatures. The emulsions, prepared as previously described, were diluted before injection into the cores. The emulsion reservoir was stirred slowly to prevent the dispersed oil droplets from creaming. Creaming was more of a... 

Coreflood Tests With Oil-Free Cores. The coreflood experiments were at first performed at ambient temperature and then extended to hot water conditions at 110 C as an approach to saturated steam conditions. Pilot experiments with the light mid-continent crude were extended to the heavier California crude oils, with steamfloods at saturated steam conditions to test the steam stability of "emulsion blocks" created with the heavier oil. The data for these coreflood tests are summarized in Table V. 

Coreflood Tests. The effectiveness of the emulsified acid is also evaluated by performing coreflood experiments [14, 15]. In each... 

Foam Diversion in Parallel Cores. To assess effectiveness of foams in reducing fluid mobility, coreflood tests are usually conducted in... 

The objective of this study was to determine the polymer flood potential in Pengrowth s East Bodo Reservoir through coreflood tests. A waterflood was conducted first on a single core, followed by a polymer flood. In this procedure, the incremental recovery of the polymer flood above waterflood recovery is clearly defined. The coreflood was conducted on reservoir core samples selected by Pengrowth with synthetic brine and oil samples from the East Bodo Reservoir to match reservoir conditions. 

The coreflood test indicated that the polymer flood accelerated the displacement efficiency. A half pore volume of polymer slug recovered an incremental 20% OOIP (after the core had been waterflooded with 1 pore volume and the water cut surpassed 90%). 

Laboratory. Previous corefloods tests by Wassmuth et al. (2002) showed that waterflood recovered 29% original oil in place (OOIP) after 1 PV of water was injected The 3 PV injection afterward of a 1,000 ppm hydrolyzed polyacrilamides (Flopaam 3630), with 50 cP viscosity at 7 s , recovered 73% OOIP (44% incremental). By mass balance, the retention of 2 mg polymer/100 g rock was estimated. Irreducible oil saturation to polymer valne was 0.22. 

Final laboratory testing of CO2 foam was performed in Shell s CT facility (11-12L Tertiary miscible and immiscible CO2 corefloods, with and without foam mobility control, were scanned during flow at reservoir conditions. The cores were horizontally mounted continuous cylinders of Berea sandstone. Table I lists pertinent core and fluid data. 

Otherwise, the formula selected is very sensitive to oil content, which is an uncontrollable variable. Note that the representation by Zhao et al. using oil vol.%/surfactant vol.% did not take into account the changes in surfactant concentration as the flood proceeds. In other words, the surfactant concentration was constant, which is true in laboratory test tubes but not in the laboratory corefloods or in the field because of surfactant retention. They also showed that the upper and lower boundaries are straight lines. 

It should be mentioned that the standard method API RP 42 has drawbacks [9]. For example, it does not take into account loss of surfactant due to adsorption on the rock surface [S, 9]. Once the concentration of the surfactant in the injected acid decreases due to adsorption or phase separation (precipitation), acid-oil sludge will form [32], Rietjens [41] recommended performing acid sludge tests using flow systems (coreflood experiments) to overcome some of the problems encountered with the API RP 42 procedure. 

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