Fifteen wells shallow gas wells producing from the Medicine Hat and Milk River formations were selected for restimulation. Wells were originally completed in the 1970’s. Despite significant pressure depletion over 30 years, refracs performed well, often exceeding initial production rates.
The use of a coiled tubing conduit for the hydraulic fracturing of shallow gas wells in southern Alberta, Canada has increased each year since its beginnings in 1997. The coiled tubing fracturing (CTF) technique has been utilized for both new and old wells as a means of fracture-stimulating multiple reservoir intervals.
This paper will detail a re-stimulation project completed during the summer and fall of 2002, in which the CTF and snubbing-conveyed fracturing (SF) processes were utilized to re-fracture a group of shallow gas wells that were originally completed in the 1970s. The objective is to examine the possible ways of enhancing production of older shallow gas wells by fracture stimulation utilizing tubing-conveyed processes.
Specifically, the paper will outline ways to consider and select wells that are candidates for re-entries, in addition to the essential work and evaluation that has to be done both prior to and following the re-entry, re-perforation, and stimulation techniques. This study will also provide a relative comparison between conventional fracturing techniques used previously and the CTF and SF processes used most recently. Also included are pre- and post-stimulation production data that give a clear indication of how effective the fracturing through tubing process is when used to re-stimulate these older wells.
Author(s): Chad Gutor, Enerplus Resources Fund; Ali Al-Saleem, Bruce Rieger, Stephen Lemp, Schlumberger Canada Ltd.Wright; Pinnacle Technologies Inc.
Paper Number: SPE 81730