Summary
Hydraulic fracturing continues to be the primary mechanism to produce
hydrocarbons out of tight shale reservoirs. Ever since the success of the
Barnett shale program, operators are inclined to pump similar large-volume
water-fracture (waterfrac) treatments with little or no proppant in their
respective shale plays. This assumes that all shale plays are the same and
react accordingly to large-volume treatments. The basic objective behind such
treatments is to contact large surface area, which has been very successful in
the Barnett shale play. Such large-volume treatments in other shale plays may
not be an optimized solution for the specific shale attributes, and the
response may lead to uneconomical production results. Some shales might require
a conductivity fracture treatment on the basis of their reservoir
characteristics. So, it is important to understand the characteristics of these
shales before deciding on the stimulation treatments. In addition to core and
log analysis of these shales, fluid-sensitivity tests, Brinell hardness (BHN)
tests, unpropped-fracture-conductivity tests, and, more importantly, a
diagnostic fracture injection test (DFIT) can help define the guidelines for
choosing between a surface-area and a conductivity-type fracture treatment.
Integrating the various data sources is important in arriving at these
guidelines. The main objective of this paper is to provide these guidelines
along with examples so that a costly trial-and-error approach for stimulating
shales can be avoided. Examples from both oil and gas shales (i.e., the Gothic,
Haynesville, Eagle Ford, and Barnett shale plays in the USA) are included in
this work.
© 2011. Society of Petroleum Engineers
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History
- Original manuscript received:
19 November 2010
- Meeting paper published:
24 January 2011
- Revised manuscript received:
6 May 2011
- Manuscript approved:
9 August 2011
- Published online:
7 November 2011
- Version of record:
22 November 2011