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2050783 
Journal Article 
Restimulation of unconventional reservoirs: when are refracs beneficial? 
Vincent, M 
2011 
No 
Journal of Canadian Petroleum Technology
ISSN: 0021-9487 
50 
5 
36-52 
English 
is also published as 2774930 Restimulation of unconventional reservoirs: when are refracs beneficial?
Restimulation treatments have been attempted in a wide variety of reservoirs, and more than 140 papers have been published documenting the success and failure of these efforts. A database of these published examples has been compiled and analyzed to identify the mechanisms responsible for production improvement following restimulation with propped fractures (refracs). A portion of this database was recently published (Vincent 2010), and specific field examples were highlighted to demonstrate that refrac treatments can improve production by numerous mechanisms, including

Enlarged fracture geometry
Improved pay coverage through increased fracture height in vertical wells
Greater lateral coverage in horizontal wells or initiation of more transverse fractures
Increased fracture conductivity compared with initial frac
Restoration of fracture-conductivity loss caused by embedment, cyclic stress, proppant degradation, gel damage, scale, asphaltene precipitation, fines plugging, and other factors
Increased conductivity in previously unpropped or inadequately propped portions of fracture
Use of more-suitable fracturing fluids
Reorientation caused by stress-field alterations, leading to contact of "new" rock
This paper will briefly review restimulation attempts in six Canadian reservoirs of interest to the local audience, and will then present a more-detailed review of restimulation of horizontal wells in the unconventional Bakken oil formation. In addition to a summary of published results, this paper will introduce a significant amount of previously unpublished data regarding refrac treatments of horizontal laterals completed in the Middle Bakken. This study will identify several additional concerns and opportunities with restimulating horizontal wellbores that were not previously identified in literature reviews. This organized summary of field results and references will provide significant value to readers evaluating or designing restimulation treatments.