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Oilfield Technology
September 2016
The FracRight systemcan be integratedwith real time DTS distributed
fibre optic stimulation and theQuest™ software suite to gather and
analyse stimulation data in unconventional reservoirs and provide amore
effective evaluation andmanagement of multi-zone completions. The
systemgathers the information required tomeasure, model and optimise
the stimulation treatment and subsequent flowback and production
profile.
The use of guide shoes provides options for circulating fluids or
allowing the string to self-fill whilst running in, to assist and direct the liner
through uneven open hole profiles.
Zonal isolation is achieved through the deployment of the
company’s swellable packers or its hydraulic soft set packers, which
are specifically formulated for frack isolation. These packers, which
have been designed with extremely low compression set forces,
avoid unwanted fracturing of the formation in inappropriate areas.
With regards to the swellable packers, the element is able to retain its
flexibility in due course and can react to any subsequent changes in
wellbore geometry.
The hydraulic set hanger packer has an anti pre-set feature,
incorporating both a primary hydraulic release and a secondary rotational
release system.
The open hole packer is a hydraulically set seal, which provides an
alternative to swellable packers. The packer achieves zonal isolation by
using hydromechanical force to set the element against the open hole.
Run as an integral part of the frack string, multiple packers are spaced out
as required to isolate between frack stages. The diff sleeve represents the
lowermost frack valve and is opened after applying pressure to the plug
string. This results in access to the first frack zone.
Anewdropball system
Once the packers have been set and effective zonal isolation has been
achieved, the frack string can be activated. Critical to the success of
the Tendeka systemhas been the development of a highly accurate
and innovative drop ball-activated fracturing process that enables the
installation of multiple sleeves for each zone to be stimulated.
Core to the success of this process has been the establishment of a ball
seat philosophy based on a fixed ratio seat, as opposed to the traditional
procedure of ⅛ in. and
1
/
16
in. increments used in the industry. This latter
methodology can be vulnerable to issues such as sleeve shifting failures,
balls firing through and poor signatureswith the uncertainties that such
malfunctions can bring.
By contrast, adopting a fixed ratio approach to the ball seat enables
a constant contact landing area per ball size, meaning that the ball is not
affected in anyway by differing ball seat sizes. It also ensures that every
seat has the same percentage of contact areawhile larger balls have an
actual, and often clearly visible, greater contact area. In contrast, the larger
ball seats adopted in the
1
/
16
in. incremental approach have a relatively
small stepwhich, when coupledwith an extremely large surface area,
has been the cause of a considerable number of failures for the industry
in the past. Another benefit of the fixed ratiomethod is that the shifting
signatures generated by the systemaremuch clearer thanwith the
standard
1
/
16
in. approach and the seat is overall more efficient, creating
more clearance, which prevents premature shiftingwhen other balls are
pumped through at a high rate.
Figure 1.
DHP Liner Hanger hydraulically set.
Figure 3.
FracRightmulti-stage system.
Figure 2.
IntegrationwithDTS andQuest software suite.
