CO2 Foam Pilot in Salt Creek Field, Natrona County, WY: Phase II: Diagnostic Testing and Initial Results

Abstract

In a previous paper we described the laboratory work, reservoir simulation, and initial design of a CO2 Foam Pilot in the Salt Creek Field, Natrona County, WY. In this paper, we review the diagnostic testing and initial results from the pilot including: injection rate profile, production data analysis, injection and production logging, chemical tracers, streamline analysis, and reservoir simulation. Although the CO2 flood has been very successful at Salt Creek, it is recognized that certain isolated patterns have exhibited high CO2 production and inefficient CO2 utilization, most likely due to the channeling of fluids through high permeability, low volume zones (fractures, thief zones, etc.) and the gravity over-ride of the injected fluids. Accordingly, a foam pilot was initiated to test the ability of CO2 to remediate these conditions. A change in the injection well rate (at constant surface injection pressure) was the first indicator to be observed; the injection rate decreased by approximately 40%, indicating a strong mobility reduction of the CO2 in the reservoir. Production and injection profile logs were run before and after surfactant injection, and a change in profile was observed in one producer. Chemical tracers were injected in both the gas and water phases before and after surfactant injection; results indicate that CO2 was diverted from high permeability, low volume conduits, such as fractures. An analysis of the production data for the four offset producers show a definite increase in liquid production and a corresponding decrease in GLR (gas-liquid-ratio.) Streamline analysis suggest areal diversion of CO2 over time. Finally, reservoir simulation prediction cases are given and discussed. CO2 flooding has become a standard EOR technique for many water-flooded fields. Methods for increasing the efficiency of these floods, such as the use of CO2 foam, can add great value.

Mixed CO2/N2 Foam for EOR as a Novel Solution for Supercritical CO2 Foam Challenges in Sandstone Reservoirs

“…Foam injection in fractured reservoirs had been investigated by several authors. Norrise et al, 18 Sanders et al, 19 Li et al, 20 and Yu et al 21 had reported several pilots for foam conducted successfully in conventional reservoir rocks. However, some modern studies prove in-situ generation of foam in a single fracture as reported by Buchgraber et al and Kovscek et al 22 , 23 This leads to improved volumetric sweep efficiency and diversion of flow within a carbonate fracture network at the time of co-injection of the gas and surfactant.…”

A Review on Foam Stabilizers for Enhanced Oil Recovery

“…There are several field trial/pilot tests conducted in different fields using foam. Scientists and reservoir engineers have conducted in-depth research with a focus on relevant chemicals and how to generate CO 2 foam by varying injection strategies at reservoir conditions. − Table lists the location and properties related to some CO 2 foam pilots for selected sandstone and carbonate reservoirs. This section discusses the summary of these five major field trials.…”

“…The pilot was initiated in September 2013. Figure shows the project workflow for piloting CO 2 -foam EOR technology. , The inverted five-spot pattern shown in Figure was chosen based on the examination of historical production and injection data was performed in each pattern in the Salt Creek field. The 22-SE30 as an injector for foam injection was located in the center of the pattern, and it was surrounded by four producers.…”

Distinguishing the Effect of Rock Wettability from Residual Oil on Foam Generation and Propagation in Porous Media

“…In situ foaming the injection gas for enhanced oil recovery (EOR) can improve the volumetric sweep efficiency of the gas phase and reduce the common problems associated with the gas-EOR, such as gas channeling and viscous fingering. − Several field pilots have been previously applied to decrease the mobility ratio between the injection gas and the in situ oil. − Foam has also been tested for conformance control and expanding the mixing zone near the injection well, − acid diversion, − and aquifer remediation. , Foam in porous media can be generated by simultaneous or alternating injection of the gas phase with the surfactant solution. The latter is more common for the field applications and generally referred to as surfactant-alternating-gas (SAG) .…”