Emulsion Injection for Enhancing the Fast-and Uniform SAGD Start-up Process
Date
2018-09-10
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Abstract
The start-up of Steam-Assisted Gravity Drainage (SAGD) process relies on months of non-productive steam circulation. A technology called Fast-and Uniform SAGD Start-up Enhancement (FUSE) has been developed to start up SAGD earlier using dilation mechanism. However, in some reservoirs there exist heterogeneities in inter-well zone along horizontal wells, which may cause uneven development of the dilation front, resulting in some low-mobility region un-swept. For the success of FUSE, it is crucial to temporarily block the high-mobility zones, so the injected fluid can penetrate into low permeability zones to form uniform dilation in the SAGD inter-well region. Using oil-in-water (O/W) emulsion as selective plugging agents seems a promising method due to the special advantages of controllable droplet size, non-permanent plugging, less formation damage of emulsion. In this work, to develop suitable oil-in-water emulsion systems, laboratory experiments and theoretical model were carefully designed. Emulsification tests were first conducted to screen suitable emulsifiers. Physicochemical properties of emulsion were characterized by stability, droplet size distribution, and rheological properties. Plugging behavior and conformance control performance of prepared emulsion were tested through sandpack flow experiments. Results show that O/W emulsion had good plugging performance when flowing in porous media with the largest sandpack permeability reductions greater than 99%. Interfacial tension significantly affects emulsion plugging behavior and conformance control ability. Emulsions with adequate interfacial tension possess favorable deformability and flexibility, which ensures they can alternately plug the heterogeneous sandpacks and obtain good conformance control performance. A new theoretical model, which incorporated physical properties of porous media, physicochemical properties of emulsion system, injection strategy and the interactions between porous media and emulsion, was developed to quantitatively describe the flow behaviors of emulsion in porous media. By appropriately choosing coefficients, the simulated results can have a well agreement to the experimental data. This work will greatly increase the understanding of emulsion flow in porous media, and provide technical guides for the optimization of the O/W emulsion injection in FUSE operation in oilfields.
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Oil-in-water emulsion, plugging behavior, conformance control, flow model
Citation
Yu, L. (2018). Emulsion Injection for Enhancing the Fast-and Uniform SAGD Start-up Process (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/33068