This paper describes the design and evaluation process for a large fracture acidizing treatment performed in a high-temperature (275° F), high-closure stress (8,000 psi), limestone formation. The subject treatment was one of several that were performed in a single gas unit. Well behavior during and after each treatment was used to optimize later treatments.

Core testing was performed to evaluate the formation’s reactivity and to characterize the etching characteristics. A fracture acidizing computer model was used to simulate potential treatment options. Both pre- and post-fracturing pressure buildup tests were performed to evaluate the formation characteristics and measure the success of the fracture acidizing treatment. Treating pressure analysis was also used to evaluate aspects of the treatment such as fluid efficiency and fracture propagation.

There was excellent agreement between the predicted and achieved fracture parameters (fracture length and conductivity as indicated by post-fracturing buildup).

Based upon the simultaneous use of core and well testing, it was possible to identify the areas of improvement for future treatments.

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