Gelation Kinetics of an Organically Cross Linked Gel at High Temperature and
Pressure

Carbonate's extreme heterogeneity in the form of fracture corridors and super-permeability thief zones challenges 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. Gel-based conformance control has been successfully applied on both sandstone and carbonate reservoirs. However, in-depth conformance control in high temperature reservoirs is still a challenge, due to severe gel syneresis (expulsion of a liquid from a gel) and the associated significant reduction in gelation time. Recently, we have demonstrated the potential of a selected gel formulation and its favorable impact on sweep efficiency for both water and chemical flooding applications in high temperature and high salinity carbonates (Wang, 2016). In the current work, the performance of polyacrylamide/chromium gel injection followed by water flooding for Arab-D carbonate reservoir rock was closely monitored by 1D T2, spatial NMR T2 mapping and 2D NMR techniques. The NMR measurements before and after waterflooding with and without pre-injection of gel provided the detailed description of spatial oil recovery along the rock core sample under reservoir condition. By comparing the spatial T2 distributions from the experiment with waterflooding and gel injection followed by waterflooding for the core sample with artificial wormhole drilled in the center, which mimics the fluid thief zone, the efficiency of the conformance control by gel was measured. The incremental oil recovery factor of ~14% OOIC after gel injection followed by waterflooding was observed throughout the whole sample with highest recovery in the vicinity of where the wormhole begins near fluid injection inlet. In addition, by analyzing the alteration of spatial NMR T2 and T2-D distribution, the accurate flow paths of the injected water and gel were derived from NMR data. The results of the current study increase the understanding of how gel could helps to increase sweep efficiency of waterflooding and other IOR/EOR applications in the presence of unwanted highly permeable channels in the reservoir rocks.

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Development and Evaluation of Foam-Based Conformance Control for a High Salinity and High Temperature Carbonate

Fuseni

Julaih

AlAseeri

et al. 2017

SPE Middle East Oil &Amp; Gas Show and Conference

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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.

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Gelation Kinetics of an Organically Cross Linked Gel at High Temperature and Pressure

Cited by 6 publications

References 22 publications

A rheological investigation of a high temperature organic gel used for water shut-off treatments

A rheological investigation of a high temperature organic gel used for water shut-off treatments

Close Monitoring of Gel Based Conformance Control by NMR Techniques

Development and Evaluation of Foam-Based Conformance Control for a High Salinity and High Temperature Carbonate

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