Multi-stage horizontal well stimulation treatments have been the key completion approach driving the recent US shale revolution. This approach has transformed the industry, making it possible to economically stimulate reservoirs that were previously deemed uneconomic.

In attempting to deploy such multi-stage fracture treatments, several tools and processes have been employed during the completion phase. Most popular among these approaches, has been the ‘plug and perf’ technique, which permits multiple treatments to be performed along a horizontal wellbore. This widespread completion approach has allowed these fracturing operations to be rapidly executed, but with the short elapsed time between stages and wells, it has become increasingly challenging for the Completion Engineer to effectively close the evaluation cycle.

As many of these shale plays now mature, it is becoming increasingly apparent that the majority of the wells have not been effectively stimulated. Fracture interference and cluster efficiency being among the key concerns with the completion approach, with high efficiency rarely being achieved resulting in only partial coverage. In fulfilling the desire to complete these wells in a timely manner, it is now apparent that there likely remains a significant portion of un-stimulated pay in a typical well post completion.

In this paper we will not attempt to address the "Optimized Completion Design", but instead explore techniques that can be used to recomplete some of these wells and recapture a portion of this bypassed pay. The paper will present the planning, the execution and the results of a five well re-fracturing Pilot programme in the Woodford Shale; including a number of reservoir simulation studies. The discussion will also address the well selection process, the re-fracturing approach and the resulting improved production rates.

You can access this article if you purchase or spend a download.