DRILLING & COMPLETION
A nano-tube matrix within nanite cement imparts strength and can be
interrogated with electrical pulses to determine the structural integrity of
new fuids. In the fnal phase, a feld demonstration will be carried
out jointly by the research partners.
With conventional primary cementing, fuids are pumped down
the casing and then up the annulus; while with reverse circulation
primary cementing (RCPC), the fuids are pumped down the annulus and up into the casing through the casing shoe. Using RCPC reduces the bottomhole circulating pressure of the fuids as compared
to conventional cementing. The primary objective of this project,
conducted by Cementing Solutions Inc. (CSI) with partners Weatherford and the University of Houston, is to assess the applicability of
RCPC techniques to deepwater wells.
One major challenge in deepwater cementing is the narrow formation fracture gradient, so the application of RCPC has clear ben-efcial potential. However, the applicability of RCPC has not been
evaluated for use in a challenging deepwater environment. The
scope of work includes analysis of the RCPC cementing method,
preparation of a development path for technology required to apply
RCPC to deepwater wells, and creation of preliminary operational
procedures with associated contingency plans. The application of
RCPC to deepwater wells is expected to reduce bottomhole circulating pressures and prevent lost circulation during cementing as well
as increase safety, strengthen environmental sustainability, enhance
zonal isolation, and improve cement seals.
In Phase I of the project, the current state of RCPC technology
and practices will be assessed and documented. Analysis will include numerical modeling and simulations, and assessments of mechanical placement controls and cementing materials. A laboratory
study will be conducted on the performance of cementing additives
spacers and the effect of RCPC on material performance. Based on
these fndings, potential benefts as well as the technical issues that
need to be addressed before RCPC can be used for deepwater applications will be identifed.
Phase II of the project will focus on the operational performance
of RCPC and the functional considerations of applying RCPC on a
deepwater rig. Phase I results will be used to determine technical
issues that need to be addressed before routine deepwater RCPC applications can occur. Further analysis will include RCPC simulations
and laboratory analyses under real well conditions and scenarios.
Operational plans will include potential contingency situations during the application of RCPC.
Nano impregnated cement
Honolulu-based Oceanit Laboratories Inc., supported by DOE
funding, is exploring oil and gas well applications for its nanotechnology concrete mix that was created as a means for strengthening
material for use in buildings, bridges, and roads.
Companies worldwide are working on ways to incorporate so
called carbon nanotubes into concrete. In addition to increasing
toughness, the nanotubes, which are thousands of times thinner
than a human hair, are highly conductive. That means that they
could be used to create a kind of nervous system within concrete
that could be used to detect cracking and weaknesses in structures.
However, many hurdles remain in the path of the promising technology, including high costs and technical barriers such as how to
create a commercial nanoconcrete manufacturing process. Oceanit
has worked to solve a key problem — how to homogeneously mix
the tiny nanotubes into a thick fuid such as cement. The company
is seeking to patent a process in which nanotubes are suspended in
a liquid concentrate that is added to the water used to make cement.
The company is developing technology for road and bridge use in
coordination with state and county transportation offcials. Initially,
the nanoconcrete would be tested for durability and strength. Ultimately, the company hopes the technology will revolutionize the
way the structural integrity of concrete is monitored, though that
application could take some time to develop.
“The carbon nanotube mixture we’re patenting acts like a spider
web within the concrete,” said Oceanit spokesman Ian Kitajima.
“Stresses in the concrete material are sensed by this internal web.
Small pulses of electricity are sent through this nano-web within the
concrete. Changes in the web refect changes in cement structure,
which affects the return signal that could be used to determine the
health of a building.”
For now, any use of nanotechnology in cement will be limited to
specialized applications because nanotubes cost more than their
weight in gold. “It is a very expensive material today, but it’s being
produced in higher and higher quantities every year,” Kitajima said.
Potential transportation applications include portions of roadways
and bridges that need stronger construction material or require
more intensive monitoring, said Barry Fukunaga, director of the Hawaiian Department of Transportation. “It’s a real innovative kind of
a product that they’ve come up with,” he said. “It’s the kind of thing
where it may be more costly, but in certain applications it could be
a good investment because of its durability and sensing qualities.”
Through the current DOE partnership, Oceanit is studying deep-water and problematic well cementing applications. •
Editor’s Note: For further information about the “smart cement” project or the
deepwater reverse-circulation primary cementing project, contact Bill Head at RPSEA
( bhead@RPSEA.org/281-313-9555) or C. Vipulanandan at the University of Houston
( firstname.lastname@example.org/713-743-4278). For further information about the nano
impregnated cement project, contact Roy Long at NETL (roy. email@example.com/281-
494-2516) or Vinod Veedu at Oceanit ( firstname.lastname@example.org/713-357-9622).