Re-fracturing Horizontal Shale Wells: Case History of a Woodford Shale Pilot Project

Abstract

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.

Parent Well Refracturing: Economic Safety Nets in an Uneconomic Market

“…This shows that refracturing can help prevent negative fracture hits. French et al (2014) discussed a well that was refractured in the Woodford for parent well protection. The production results for this well are shown in Fig.…”

“…these 5 basins in other papers (Ajani and Kelkar 2012;Diakhate et al 2015;French et al 2014;Kurtoglu and Salman 2015;Martinez et al 2012). The locations of known positive and negative hits were plotted on a map to determine if there are any areal trends to the fracture hits ( Fig.…”

Effective Technology Strategy for Shale Plays

“…(3) To summarize, here are some of the techniques needed in sweet spot optimization:  Better integration with sequence stratigraphy, geochemistry, imaging, XRF, etc.  Under development: Whipstocking the Sweet Spots  Whipstock directional drilling for better penetration of sweet spots  Whipstock off the lateral where microseismic indicates a fracture pod  Packers or sliding sleeves to perf within the whipstocked part of the lateral?…”

The Key and the Countermeasures Research of Shale Gas Fracturing Technology

“…Multi-stage fracturing technology is the main hydraulic fracturing technology for shale gas application [17]. The horizontal well technology has been widely used in shale gas production in America.…”