DRILLING & COMPLETION
Research effort aims to enhance
cement integrity in deepwater
Project targets real-time monitoring with ‘smart’ mud
Improving cement integrity in deepwa- ter applications is one of the primary foci of the National Energy Technology Laboratory (NETL), a division of the US Department of Energy. Within NETL’s
national laboratory system, under the direction of the Offce of Research and Development, and in concert with industry and
academia, work is advancing in many areas,
from reverse circulation cementing to smart
cement. The following describes three projects designed to monitor and enhance cement integrity in deepwater environments.
Measuring electrical
resistivity in smart cement
This ongoing project, undertaken by the
University of Houston with partner Baker
Hughes and funded by DOE through the
Ultra-Deepwater and Unconventional Natural Gas and Other Petroleum Resources Research and Development Program administered by the Research Partnership to Secure
Energy for America (RPSEA), seeks to develop technology for real-time monitoring of
cement installation and performance during
the service life of deepwater wells. In this
study, various technologies will be used to
develop “smart” drilling mud and cementing
slurry with enhanced sensing properties,
so that they can be deployed for real-time
monitoring during installation and the entire
service life of a deepwater well.
Advances in materials and grouting technologies will be combined with advancements in surfactant technology to produce
drilling mud and cementing materials with
enhanced sensing capabilities. With the
sensing capabilities installed in the drilling mud and cementing slurry, it also will
be possible to monitor the advancement of
the drilling mud and cementing slurry front
around the casing during the construction
phase.
The smart drilling mud and cement slurry will be modifed such that its short-term
and long-term piezoresistive characteristics
refect the composition, chemical reactions,
and surrounding environment (temperature
and pressure) that infuence changes in internal stresses. Changes in stress, strain,
and/or temperature will cause a change in
the electrical resistivity of the smart fuid,
refecting the condition of the cement slurry
in the borehole and measuring, for example,
the length of cement supporting the casing.
The long-term piezoresistive charac-
teristics will be infuenced by the stresses
induced in the borehole and the condition
of the solidifed cement materials. The cas-
ing will be modifed with outside rings at a
set spacing to monitor the changes in the
electrical resistivity and temperature of the
drilling mud and cementing material that
stabilize the casing and the borehole. This
will make it possible to identify the loca-
tions that are highly stressed in the cement
sheath surrounding the pipe. In addition,
other damages caused by the stresses and
temperature conditions in the borehole will
be identifable during the service life of the
cemented casing.
The technical study will be completed
in three phases over a total of three years.
In Phase 1, smart drilling mud (SDM) and
smart cementing slurry (SCS) will be developed with conductive fllers (solutions
and particles) and fbers that do not affect
the fowability characteristics of the drilling
mud or cement slurry. The SDM and SCS
will be characterized based on fltering, fuid
loss, piezoresistivity, and rock interaction.
In Phase 2, small and large model tests are
planned to demonstrate the potential for the
Roy Long
National Energy
Technology Laboratory
US Department of Energy
Conventional and reverse circulation placement of primary cement job. (Images courtesy National
Energy Technology Laboratory, US Department of Energy)
