A horizontal water injection well with limited entry liner (LEL) completion in an onshore Middle East carbonate reservoir was stimulated with HCl using a large volume of viscoelastic diverter acid (VEDA) fluid system ahead of the main acid stage. The VEDA stage was needed to deliver sufficient acid volumes to the toe of the well resulting in a significant increase to the injectivity index and more even distribution of injected water across the horizontal drain.

VEDAs have been successfully used to achieve diversion in openhole and casedhole perforated completions for years. However, VEDA stages have rarely been used in LELs because the liner design typically ensures even distribution of acid across the completion. In this case, due to a large contrast in permeability between the heel and toe of the well, the mechanical diversion of the LEL is enhanced chemically by including VEDA for even distribution of injected fluid to all compartments. Near-wellbore modeling showed that the inclusion of a VEDA stage ahead of the main acid stage could provide temporary diversion of acid from the heel to the toe compartments, resulting in more uniform wormhole length and stimulated skin profiles.

The VEDA was pumped successfully through the small 4-mm openings in the liner, and the stimulation job was able to be pumped at the maximum rate achievable by the pumping equipment. The stimulation increased the injectivity index by approximately a factor of 4. The VEDA stage produced more than 600 psi of diversion pressure in the heel compartments. The post-stimulation injection log confirmed the success of the stimulation by showing more even distribution of injected water across the entire horizontal drain, despite the contrast in the native (unstimulated) permeability between the heel and toe compartments.

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