Lessons Learned: Refracs from 1980 to Present

Abstract

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.

Review of Shale Oil and Gas Refracturing: Techniques and Field Applications

“…), and the fracturing materials are basically the same as the first fracturing. The general temporary plugging refracturing technology has a low cost and a simple process [29,30]. However, the challenge of precisely controlling the temporary plugging positions results in highly variable construction outcomes.…”

“…However, some scholars believe that, even if the construction pressure gradually increases, it does not necessarily indicate that the refracturing has diverted into new areas. For example, in a shale gas well in the Woodford block, the construction pressure gradually increased, but there was basically no increase in the post-fracturing production [30]. Agharazi et al [41] argue that, in the presence of many perforated clusters, it is difficult for refracturing to generate new fractures.…”

Semi-Analytical Rate Decline Solutions for a Refractured Horizontal Well Intercepted by Multiple Reorientation Fractures with Fracture Face Damage in an Anisotropic Tight Reservoir

“…Jiang et al [13] formulated a theoretical model to evaluate the production decline performance of a fractured vertical well with reorientated fractures in an anisotropic formation and examined the effect of orientated fractures by generating Agarwal-Gardner-type decline curves. Real-time diagnostic techniques have been recognized as potential tools for preand post-refracturing analysis [31,32], but there is no report on the instantaneous rate decline solution of refractured horizontal wells, and the influence of reorientation fracture properties on the instantaneous rate decline is still unknown.…”

Review of Key Parameters for Proppant Hydraulic Re-Fracturing Technology

“…Old proppant displacement 1. In case of old proppant placed in unsatisfactory mode, possible solutions should be to consider old proppant displacement by diversion methods [17].…”