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Self-Diverting Emulsified Acid for Stimulation of Iranian Ab-Teymur Carbonate Reservoir
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 79th EAGE Conference and Exhibition 2017, Jun 2017, Volume 2017, p.1 - 5
Abstract
Matrix acidizing in carbonate reservoirs is a common practice to remove formation damage by dissolving the rock and creating wormholes. In order to maximize the effectiveness of the stimulation, treatment fluid must be diverted to fully cover the damaged zone and the flowback be eased to remove the damage. Fluid diversion becomes of prime importance in multilayered reservoirs where preferential flow pathways take in most of the stimulation fluid and the lower permeable zones remain untreated.
We develop a self-diverting emulsified acid that minimizes the post treatment damage by maximizing treatment coverage and enables easy flow back. More than 20 emulsifiers are investigated to find the most effective mixture that results in a stable emulsion with desirable viscosity. We use interfacial tension test to find the optimum emulsifier concentration. Rheology of the emulsion is measured under four different conditions, mimicking the flow from surface to reservoir.
We found out that an emulsifier with the oleic, linoleic, linolenic and resin acids results in the most stable mixture with the highest viscosity and smooth flow back that maximizes the rock-acid contact and minimizes the post-treatment residual damage. In addition, we recommend using the SDEA as a fluid packer in multi-batch acid system.