Summary
As the development of tight/unconventional and partially depleted gas
reservoirs has increased, so has the demand for more-innovative
hydraulic-fracture designs. Operators are increasingly placing proppant with
slickwater, linear gel, or hybrid fracture designs. While the benefits of these
designs typically are attributed to a reduction in gel damage of the proppant
pack, many operators mistakenly believe that the resulting fractures are not
conductivity-limited.
Because few (if any) models on the market can adequately model the
propagation of a slickwater fracture along with the associated proppant
transport and deposition, it becomes difficult to optimize these fracture
designs. This has led many operators to assume incorrectly that only
small-diameter sand or resin-coated sand may be placed in these types of
designs, and that these products supply ample flow capacity.
However, one east Texas operator has combined insight into proppant
transport with an appropriate understanding of realistic proppant-pack
conductivity to develop a novel, hybrid slickwater-fracture design. This design
has allowed the placement of larger-diameter, higher-conductivity proppant in
fractures that many believed could not be placed in fractures either
operationally or economically. Additionally, this operator has developed a
unique pumping strategy to place the highest-conductivity proppant in portions
of the fracture where it provides the most value.
This paper will present a case history of these new hybrid
slickwater-fracture designs in this operator's east Texas Cotton Valley Taylor
(CV-T) completions. The design theory and sequential improvements will be
documented, including larger-diameter, higher-strength proppants, and a novel
placement design. Field results from the first six wells fractured will be
presented, showing substantial increases in gas production compared with
similar offset completions. Economics will also be shown to illustrate the
tremendous value added to completions using this hybrid fracture design.
© 2009. Society of Petroleum Engineers
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History
- Original manuscript received:
30 July 2007
- Meeting paper published:
11 November 2007
- Revised manuscript received:
22 December 2008
- Manuscript approved:
27 March 2009
- Published online:
30 July 2009
- Version of record:
8 September 2009
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