Refracturing in the US midcontinent is not a new method. In 1980, a refracturing program was begun in the shallow, low-pressure Brown Dolomite gas pay in the Texas panhandle. The results were mixed, but the overall outcome was economically beneficial. Currently, operators are refracturing horizontal shale wells, especially those completed from 2003 to 2010. However, results continue to be mixed and unpredictable. This paper presents lessons learned during refracturing treatments performed between 1980 and the present that led to the creation of a new approach to refracturing treatments.
This paper discusses the factors to consider when planning a refracturing program. Refracturing failures are also discussed as a means to understand the controllable and uncontrollable variables that lead to these failures. Failures are categorized and specific failure types and modes are identified. Examples of successful refracturing treatments are also included.
The resulting newly developed refracturing approach includes a four-step process:
Candidate identification Refracture diversion design Execution and diagnostics Production analysis and diagnostics
Examples of using the four-step process are provided to show the incremental improvements that resulted from identifying potential candidates and designing, executing, and analyzing the project. Production results and incremental estimated ultimate recovery (EUR) values are discussed to illustrate the economic viability of refracturing, and the economic benefit of this incremental production increase is compared with the cost of the refracturing treatment. While incremental production from refracturing in the midcontinent has more than doubled, pre- and post-fracture diagnostics should improve the success rate by defining lateral coverage. Real-time diagnostic techniques are discussed as potential tools for pre- and post-refracturing analysis.
Despite the history of mixed results, refracturing efforts are improving through the implementation of this new four-step approach. Repressurization of the original fracture system is common to successful refracturing throughout time. New diversion materials and placement processes help achieve repressurization and refracturing placement success. Also, additional insight from new diagnostic tools and techniques can help improve the overall refracturing project success.
