Underground Infrastructure - February 2023 - 37

CIGMAT Report
FIGURE 8: Cleaning efficiency test using viscometer (a) drilling mud
contaminated cylinder and (b) after cleaning with the spacer fluid.
the addition of nanoFe2O3 at 25°C temperature. Th e root mean
square of error was in range of 1.23 to 2.16 Pa (TABLE 4).
Cleaning Effi ciency. Th e cleaning effi ciency test to evaluate
the smart spacer fl uids in cleaning the bentonite drilling
mud contaminated metal cylindrical tube (from the viscometer)
was performed as shown in FIGURE 8. Th e weight of the
metal tube was measured before contamination, aſt er contamination
and aſt er cleaning. Th e cleaning effi ciency of the spacer
fl uid was 82.3% without adding nanoFe2
O3
to 99%, as shown in FIGURE 9.
Maximum shear stress (τmax
. With the addition
of nanoFe2O3 cleaning effi ciency increased 20.7%, from 82%
cated bett er cleaning ability of spacer fl uid with 1% nanoFe2
as shown in FIGURE 10. Th e τmax
) of the smart spacer fl uid indiO3
,
increased
32.5%, from 49.4 to
65.5 Pa; with the addition of 1% nanoFe2O3, cleaning effi ciency
increased from 82 to 99%.
Th e relation between maximum shear stress and cleaning
effi ciency for the smart spacer fl uids was modelled using
Vipulanandan Cleaning Effi ciency model in Eqn. (7). Th e
model parameters E and F were 0.49 Pa% and 0.0025%, respectively,
for the cleaning effi ciency model. Th e R2
and RMSE
for the model were 0.99 and 1.53%.
Increased effi ciency was primarily due to bett er rheological
properties, which produced higher shear stresses for cleaning
and high surface-to-volume ratio of the nanoparticles. Th e
maximum shear stress required to generate 100% cleaning effi -
ciency was about 67 Pa.
Conclusions
In this study, smart spacer fl uid samples were tested for material
characterization, rheological, cleaning effi ciency and
piezoresistivity behavior. Also, the eff ects of the magnetic fi eld
strengths, temperatures and bentonite contamination on the
electrical resistivity and rheological properties of nanoFe2
modifi ed spacer fl uid were investigated.
O3
From the experimental study and analytical modeling, the
following conclusions are advanced:
1. Based on the material characterization, resistivity
FIGURE 10: Relation between maximum shear stress and cleaning
efficiency of the spacer fluid.
proved to be the sensing electrical property of the
smart space fl uid.
2. Electrical resistivity of the spacer fl uid decreased with
increasing temperature, and it was an accurate sensing
parameter for real-time monitoring to predict the
rheological properties in the fi eld.
3. Th e addition of up to 1% nanoFe2
stress, shear thinning behavior, and ultimate shear
stress limit of the spacer fl uid. Also, the Vipulanandan
Rheological Model closely predicted the experimental
results, based on the root mean square error (RMSE).
Changes in the properties were infl uenced by the
temperature, nanoFe2
O3 content, and magnetic fi eld
strength, and were quantifi ed using the Vipulanandan
Correlation Model.
4. Th e smart spacer fl uid with nanoFe2
O3 showed bett er
rheological properties than spacer fl uid without
nanoFe2
O3. Th e ultimate shear stress, a new rheological
property quantifi ed by the Vipulanandan Rheological
Model of the spacer fl uid, correlated well with the
cleaning effi ciency.
UndergroundInfrastructure.com | FEBRUARY 2023 37
FIGURE 9: Cleaning efficiency of spacer fluid with varying
NanoFe2
O3
content.
O3 modifi ed the yield
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