Initial treatments utilized <500,000 lb sand. Over time, designs specified more sand with less frac fluid. This paper describes 7 refracs designed for 2 million lbs reaching 10 ppg concentration. All 7 refracs were successful, average benefit 1030 mcfd/well, FOI=3.6, Incremental reserves estimated at 1 bcf/well by operator, GRI estimated 1.88 bcf/well. Wells with highest pre-frac kh responded best to increases in proppant mass and concentration. Post-frac buildup suggested 250 ft with conductivity of only 300 md-ft.
Under certain circumstances, restimulation of tight gas sand wells may provide an excellent investment opportunity. Graham-McCormick Operating Partnership conducted a refracturing program within the confines of the Oak Hill (Cotton Valley) Field which may provide insights for other operators contemplating similar work.
This paper explores the criteria used to identify refrac candidates and examines the important considerations in the design process. A well-by-well discussion describes implementation of the treatments and evaluates post-frac performance. Refrac economics are reviewed in the closing section.
Author(s): J.C. Hunter, Graham Resources Inc.
Paper Number: SPE 14655