Maintaining reservoir pressure and safeguarding the formation
Deepwater offshore projects, especially those involving floating
production, storage, and offloading (FPSO) vessels, require massive commitments
in planning, detailed product selection by recognized product experts, and
reliable, efficient execution to achieve the system performance that
stakeholders demand. Many of these applications require injection wells to
maintain reservoir pressure as the hydrocarbons are extracted. During the
completion design for wells located in deep waters off West Africa and Brazil,
two operators performed rigorous evaluations to determine the value of their
completions' valve designs, both in effectiveness and in the reliability of the
installations over the life of the wells. Both companies needed to reliably
safeguard their formations and cost-effectively maximize injection flow rates
for reservoir pressure maintenance.
Switching to valves with larger inner diameters
Both operators had separately identified that injection flow rates
through the smaller inner diameters of traditional
through-tubing−installed injection valves were inadequate to support the
reservoir drawdown rates required. Therefore, a larger inner-diameter valve
design was necessary to achieve production goals.
After thorough engineering evaluations, the operators concluded that the
Schlumberger tubing-retrievable Integrity injection valve provided the best
capabilities for their projects.
This valve's larger inner diameter allowed increased flow, along with
efficient, reliable operation, without the need for a separate control
mechanism, making the valve attractive for their water-injection applications.
In addition, the through-tubing integral choke replacement allowed the valve to
operate effectively within a wide range of injection rates.
In May 2005, one of the operators began developing a field located
offshore Port Harcourt, Nigeria. The field development plan called for 22
producing wells, 20 water-injection wells, and 2 gas-injection wells, tied back
to an FPSO vessel.