Formation damage removal using matrix acid stimulation in Sandstone reservoir is recognized as a risky production optimization operation, however, a good understanding of formation mineralogy, root cause of formation damage, and stimulation procedures can help reduce the risk and increase the chance of success. The scope of this paper is to share Eni Pakistan’s workflow which lead to successful matrix acid stimulation campaigns in Bhit, Badhra and Kadanwari fields.

Prior to the damage removal operation, the selected wells’ deliverability analysis showed low productivity as compared to the ideal one. To restore the ideal wells’ productivity index, detailed damage analysis was performed as per following workflow.

  1. Perform pressure transient test to evaluate and quantify the level of damage

  2. Evaluate individual perforation contributions using production logging tools

  3. Assess the origin of damage by reviewing the drilling, completion operation

  4. Estimate the possible gain in production after removing the damage

  5. Define the proper chemical requirements and design the stimulation procedures and perform Post stimulation analysis to optimize the stimulation procedure prior to the next job if required.

Seven candidate wells were selected for damage removal operation. The matrix stimulation operation resulted in incremental daily production of up to 160%. The increase in the production rate was accomplished by regaining the wells’ potential deliverability. This helped improve the fields’ reservoir management, accelerating hydrocarbon recovery and adding to the reserves.

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