Notional Field Development Final Report - EBN

EBN Notional Field Development Plan
3.5.2 Completion Design
3.5.2.1 Considerations for Completion Design
The vast majority of shale development wells are multistage completions, comprising of an isolation
method, which is used to separate each fracture interval and treatment, a perforation /fracture
initiation method, and the fracture treatment (fluid and proppant). The primary isolation methods used
in these wells are: open hole, cased and cemented, cased and uncemented isolation or sliding sleeves
and packers.
Cased and cemented horizontal completions offer a high degree of control of the fracture treatment
placement, whereas open hole and uncemented annulus completions offer greater access to and have a
better chance of stimulating a larger area within the interval. Uncemented completions use external
mechanical and swellable casing packers to achieve zonal isolation. Swellable packers exert far less
pressure on the formation than mechanical packers making them a better choice in less competent rock
such as shale. The key differences between an unconventional shale well and a conventional well are in
the completion design and stimulation methods that are applied. The objective in shale fracturing is to
create a dense network of branch fractures, whereas fracturing in conventional reservoirs creates
simple biwing fractures.
Some shale reservoirs consist of individual laminated zones of < 1-ft thickness, that require pinpoint
fracture placement, while others consist of thicker or massive shale beds that require a different
method of fracture placement. Selection of the fracture initiation locations is largely based on TOC
content and brittleness.
Depending on the type of zonal isolation technique employed, a fracture staging method from one of
the following groups is typically used:
• Perf-and-Plug Processes
• Sliding Sleeve Processes
• Pinpoint Stimulation Processes
3.5.2.2 Completion Processes Used Today
Perf-and-Plug Process
Wireline perf and plug method offers the ability to fracture stimulate multiple intervals where isolation
between intervals is achieved using pumpdown plugs. The plug and perforate process can be applied in
cased and cemented completions, and in cased completions using open hole packers. This technique
involves running in the hole with conventional guns to perforate an interval, pulling out of the hole,
pump the stimulation treatment, pump the plug to isolate the interval, and then run in the hole with
guns to perforate the next interval. While there are many advantages when applying the plug and
perforate process, such as that it is a simple process with economically acceptable results, there are
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