For many years retained proppant pack conductivity has been used as a major tool in the prediction of optimizing production. As a result, standardized methods of performing proppant pack conductivity tests have been developed and published. The objective of this study was to determine the difference in near wellbore, mid-fracture, and "tip" cleanup of polymer in the proppant pack during fracturing treatment flowback. To ensure optimum formation production, consideration of polymer cleanup between the mid-fracture and the "tip" is necessary to limit the possibility of production limitations due to pressure drop along the fracture length. Cleanup of a proppant pack is influenced by many factors: fluid leak-off, fluid and breaker chemistry, formation mineralogy, fines migration (i.e. crushed proppant and fluid loss additives), temperature, pressure, etc. This study focused on the different cleanup effects determined by the rate and direction of flow in the proppant pack.

The testing methodology used in this study focuses on evaluating the different parameters encountered during actual fracturing treatment flow-back:

  1. Removal of filtercake and insolubles due to breaker.

  2. Rate of removal of filtercake and insolubles due to flow rate in the fracture.

  3. Rate of removal of filtercake and insolubles due to rate of flow through the filtercake into the proppant pack.

  4. Rate of removal of filter-cake and insolubles due to interactive flow directions.

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