Carbonate reservoirs’ extreme heterogeneity in the form of fracture corridors and super-permeability thief zones present challenges to the efficient sweep of oil in both secondary and tertiary recovery operations. In such reservoirs, conformance control is crucial to ensure injected water and any EOR chemicals optimally contact the remaining oil with minimal throughput. Foam-based conformance control is a relatively new technology especially its use for in-depth diversion in high salinity high temperature conditions. In this work, a laboratory study was conducted to develop and evaluate a foam-based conformance control technology for application in a high salinity and high temperature carbonate. Foaming agents were first screened for their suitability with regard to reservoir temperature and salinity where properties such as foamability and foam stability were measured. The best performing surfactants were then used to study the mobility reduction across a core composite at reservoir temperature and pressure. Foam stability and decay were also investigated in those permeability reduction experiments. Brine and crude oil were injected after foam formation and pressure drops and sustainability of mobility reduction were quantified. The improvement in reservoir contact and hence oil recovery were examined by oil displacement experiments conducted in specially prepared heterogeneous composites. For the studied conditions of high salinity and high temperature, foaming agents of the amphoteric family as well as a special blend were found suitable in terms of salt tolerance and foam stability. The mobility reduction due to foam was 12 times without oil and 6 times in the presence of oil. Oil recovery improvement with foam application was also found to be significant. These results demonstrate the potential of the identified foam system and its favorable impact on sweep efficiency despite the harsh salinity and temperature conditions of the studied carbonate reservoir.
TX 75083-3836, U.S.A., fax +1-972-952-9435. AbstractThin reservoirs of a few feet in thickness present a clear challenge to well placement. Drilling out of the target is a real possibility, and plugging back and reentry can be extremely difficult. Clearly, the best solution is to avoid exiting the target reservoir by detecting approaching boundaries as early as possible and by remaining at an optimal distance from the boundaries. This practice is known as "proactive geosteering." In recent developments, wave resistivity LWD and azimuthal wave resistivity sensors have been shown to effectively facilitate proactive geosteering. Their abilities to scan laterally several feet, up to more than 10 ft, around the wellbore and to identify the relative azimuth of approaching boundaries have been instrumental in recent successes.The challenge posed by the subject reservoir in this study is the combination of the thinness of the reservoir, approximately 3 ft, and the high resistive environments of the boundary, zero-porosity anhydrite formations, as well as the oil reservoir containing a low porosity dolomite layer. The challenge was met by carefully selecting the most appropriate measurements to send to the surface, interpreting them in real time, and using multi-boundary inversion. A series of pre-well simulations were run using offset wells. The simulation results showed that for the most likely scenario, shallow azimuthal wave resistivity curves and images provided the highest sensitivity to the approaching boundary. Medium and deep resistivity curves were less active and of lower resolution, but they contributed to the inversion for dual boundaries. Newly generated high resolution electric and density reservoir imaging and petrophysical logs were also interpreted in real time to assess the relative dip and provide finer control of the well angle. They helped to verify that the well remained within the reservoir through nearly its entire span, i.e., that the well was successfully placed with a high net-to-gross in a very thin reservoir in resistive environments.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.