During a half-year field test a novel method was applied for water injection during waterflooding in a weakly consolidated, heavy oil reservoir (90–120 cP). The injection has been combined with a hydraulic pulsing tool downhole in the injection well to provide additional dynamic pressure pulses on the order of 4–17 bar, with 5–6 pulses per minute. The technology has been developed in Canada and applied successfully, especially as a well stimulation technique in order to initiate or stimulate oil production with sand coproduction. The first objective was to see whether pulsing would be beneficial for the efficiency of the injection process. Furthermore, laboratory experiments and theoretical developments suggest that pulsing might improve the sweep efficiency of the flooding pattern. Hence, the promise of this technique would be potentially faster and higher oil recovery during waterflooding. In the design of the field test it was chosen to keep the total water injection rate on the same level as before pulsing was applied, on the order of 110 m3/d. The rationale behind this decision was that previous experience in the field has shown that higher injection rates resulted in pressurization of the reservoir and increased fingering. In addition, the fixed injection rate allowed us to focus on improvements in sweep efficiency, without correcting production figures for the higher injection rate.

Pressure Pulse Technology (PPT) was applied without any significant operational problems for half a year although severe corrosion problems unrelated to the PPT project were uncovered after the trial. Injection and production performance has been monitored before, during and after the test. When pulsing started, injection pressure dropped, and even after the pulsing stopped a lower wellhead pressure has been measured. With constant injection rate this shows an improvement in injectivity. It also indicates a significant reduction in near wellbore skin factor or possible improved injection conformance. The injection water used is considered dirty and potentially deteriorates injectivity over the life of the well. Indications are that injection pressure is now slowly building up again following the trial.

Improvements in production have not been confirmed by this field trial. The accuracy and repeatability of the production measurements have not assisted in identifying the potential effect. However, the field trial results have enabled us to recognize the potential use of the technology for an efficient high-rate injection strategy. Possibly this would avoid injection under fracturing conditions. We outline situations where such applications would be desirable. Higher injection rate and more efficient pulsed injection potentially lead to improved recovery, although actual improvements need to be assessed with further tests.

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