An Integrated Experimental Method for Investigating Sequential Injection Acidizing in Carbonate Formation

Area of Science:

• Petroleum Engineering
• Reservoir Stimulation
• Acidizing Techniques

Background:

• Sequential injection acidizing is used for acid diversion and deep penetration in high-temperature reservoirs.
• Limited research exists on its impact on wormhole development.

Purpose of the Study:

• Investigate the mechanisms of sequential injection acidizing, focusing on wormhole development.
• Evaluate its effectiveness in high-temperature carbonate formations.

Main Methods:

• Integrated experimental approach: fluid performance evaluation, core flooding, and computerized tomography (CT) imaging.
• Selection of acid combinations and performance investigation in carbonate reservoirs.

Main Results:

• Sequential injection acidizing requires less acid and lower pressure drop for deeper core penetration than single-stage stimulation.
• CT imaging revealed enhanced wormhole randomness and formation of dispersed, interconnected large dissolution pores.
• This technique improves acidizing efficiency, especially in high-temperature reservoirs.

Conclusions:

• Sequential injection acidizing offers synergistic benefits for carbonate reservoirs, particularly at high temperatures.
• Provides insights for designing and selecting acid stages for improved wormhole penetration.
• Suggests further experiments with more acid stages using the integrated method.