Application of High-Pressure Squeeze Acid Across Wellhead Technology for Water Injection Well
Acidizing has been frequently used to dissolve the plug or debris in the zone. Due to the debris which plugged the zone, the injection pressure rises higher. The water injection rate cannot meet the demand of production department. Conventional acidizing treatment in high-pressure water injection wells needs rig operation to install a higher pressure rating wellhead after bleeding off pressure and pulling operation. The complex procedure makes the operation cost expensive. What is more, bleeding off pressure leads to pressure reduction of formation, which needs a long time of pressure buildup. High-pressure squeeze acid across wellhead technology has been developed to reduce the rig cost and operation time while decreasing damage to the formation. Before acidizing operation, the in-tubing sealing tool is run inside the first tubing below the tubing hanger through vertical passage of the wellhead equipment by special snubbing device. The in-tubing sealing tool sets in the tubing. The acid fluid is pumped into the tubing directly through surface cock valves manifold. The wellhead would not be affected by the acid fluid of the acidizing processes since it has been isolated from the tubing by the in-tubing sealing tool. High-pressure squeeze across wellhead operations has been conducted in 18 wells successfully for several oilfields, such as central Hebei and Erlian. The peak pressure in these operations is double of the working pressure rating of wellhead. The technology can significantly improve operation efficiency, reduce costs, and avoid formation damage caused by workover. It has made an innovation than conventional acidizing treatment and shows a wide application prospect.
KeywordsHigh-pressure water injection well Acidizing operation Wellhead isolation Snubbing
The authors would like to thank Petroleum Production Engineering Research Institute of Huabei Oilfield Company to permit the publication of this work.
The work and dedication of the all personnel involved in the execution of the operations and testing are greatly appreciated.
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