Hydraulic fracture reorientation is not the only reason to restimulate a reservoir. The need for restimulation following a primary fracture treatment can be split into three categories.
- Reorientation - Remediation - Bypassed Pay
Fracture reorientation has been the most successful restimulation category by far with hundreds of refracture treatments in Barnett shale wells and thousands of refracture treatments in wells producing from the Codell formation of the DJ basin.
Fracture remediation may be necessary when the primary treatment was not pumped as designed or when time, environmental conditions, and production result in fracture damage.
The category with the most technical difficulties, but with the greatest potential to increase EUR, is the restimulation of inadvertantly bypassed pay in wells producing from multiple layers. Fracture imaging from microseismic maps, radioactive tracers, production logs, and pressure diagnostics typically show up to 30% of the layers targeted for stimulation are often inadvertently bypassed or ineffectively stimulated.
All too often, restimulation candidates are identified by a cursory well file review and treatments are designed and pumped without diagnosing a problem. In wells producing from multiple layers, experience shows that this approach leads to unsatisfactory restimulation results.
Reservoir Development's technology was developed specifically to add a diagnostic step to restimulation-candidate identification. Diagnostics allow restimulation treatments to be designed for specific well conditions hindering production in addition to determining when restimulation is unnecessary. Using the new diagnostic technology, it is now possible to selectively target the 30% of the layers that are bypassed and increase well productivity by isolated-layer restimulation.
Traditional, and often unsuccessful, approach to restimulation candidate identification and stimulation--no effort to diagnose production problems.
Improved method to increase restimulation success -- Restimulation Candidate IDs - Identify, Diagnose, and Stimulate
Craig, D.P. and Blasingame, T.A.: "A New Refracture-Candidate Diagnostic Test Determines Reservoir Properties and Identifies Existing Conductive or Damaged Fractures,” SPE 96785 presented at the 2005 SPE Annual Technical Conference and Exhibition, Dallas, Texas, 9-12 October 2005.
Craig, D.P. and Odegard, C.E.: "Identifying Bypassed and Ineffectively Stimulated Layers In A Well With Commingled Production From Multiple Layers: Mesaverde Case History," paper SPE 114777 presented at the 2008 SPE Unconventional Reservoirs Conference, Keystone, Colorado, 10-12 February 2008.
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