Good Applications of Foam Cement in Geothermal Wells and Deepwater Environments during oil and gas wells drilling.

1. Good Applications of Foam Cement
in Geothermal Wells and Deepwater
Environments
Salman Deumah
May 2021

2. Introduction
❖ Foamed Cement Slurry :
A foamed cement slurry is a cement slurry in which gas (air, or
even more often, gaseous nitrogen), is incorporated directly
into the base cement slurry provides the benefit of increased
slurry compressibility, increase set-cement elasticity, and the
flexibility to reduce density during. In this way, an ultra-
lightweight cement slurry is obtained.
❖ Foam Cement Chemistry:
✓ Foam cement is made by properly combining three
elements: cement slurry, foaming agents, and a
gas(usually nitrogen).
✓ Foam is one in which the gas volume makes up 60% of the total foam volume. The higher the quality
(i.e., nitrogen content) of a foam slurry, the “thicker” or more viscous it will act.
✓ Some admixes otherwise commonly used should not be used when foaming.
✓ Nitrogen is the preferred gas for foam-cement jobs. However, for certain low-pressure or shallow
applications, compressed air could be used, including nitrogen (78%), oxygen, (21%), other gases, and
water vapor

3. Location of Application
Fields
Location of
Application
In the deep offshore of
the Gulf of Guinea , in
2011.
In the most wells drilled in
2015–2017 in the Volga-Ural
Region of Russia
In the geothermal-
drilling operations in a
field in central California,
In 2010.
Problems
There are the deep water weak
formation environments, that can
causes the following problems:
-A lower fracture gradient
resistance than the same formation
at the same sedimentary depth
onshore.
- Reduction in the equivalent
fracture density which may causes
the fracturing a weak Formation
and lost circulation
Oil reservoirs in this region are
mostly fractured carbonate deposits,
which causes the following
problems:
- Increasing risk of drill mud
losses.
- Increasing in the total non-
productive time (NPT), that may
take up to 30 days (about 50% of
the rig time)to stop these
disastrous losses by us other
conventional cements.
Areas where the presence
of naturally occurring
brines, steam breakout,
carbon dioxide, and
especially weak formations.
These challenges causes
these following problems:
- Lower the fracture
gradient formation
- Severe lost circulation
- Increase non-productive
time during using
conventional slurry
cements.

4. Conventional Cements Limitations
❖ Conventional cements limitations:
➢ Specific geological features of the region.
➢ High equivalent density of conventional cements.
➢ The conventional cement is lost in the thief zones before it starts to set, due to gravity and other factors.
➢ The flow of formation water washes the plug away leaving the thief zone either
not isolated at all or partially covered with the remaining cement .

5. Process and Mechanism
❖ Process of using the foam cement and mechanism:
➢ Foam cementing uses a foam water spacer and/or foamed drill
mud to help reduce hydrostatic pressure in the well to below the
loss initiation point and create a "blanket" below the foamed
cement to help prevent loss of foamed cement deep into the thief
zone (Fig. 3).
➢ Foamed cement injected into the thief zone occupies all space
available in all directions due to compressibility/expansion,
completely fills caverns and fractures, and locally penetrates
deep into vast cavernous karst zones. After waiting-on-cement
(WOC), foamed cement is drilled with a bottom hole assembly
(BHA)(Fig. 4).
➢ In this case, mud return is 100% if only one thief zone is present.
If there is more than one zone with different loss pressures,
additional operations are required in most cases to isolate each of
the zones separately.

6. Importance of Foam Cement Application
❖ Foam Cement Benefits :
Foamed cements exhibit several properties that make them suitable for use in well construction in the mentioned
regions:
Advantages Unique Features or properties
Lost circulation control Lightweight (high strength and low density).
Improve long-term zonal isolation Ductility and tensile strength
Improved mud displacement High viscosity
Stabilizes at high temperature and retention of heat as
fluid is injected into the well.
Lower thermal conductivity (Insulates)
Reduced costs associated with materials and rig time. Provides excellent strength-to-density ratio
Prevent gas migration control Foam with the tiny and discrete bubbles
Lower Environmental Impact Nitrogen is noncorrosive, nonreactive and inert.
Has low permeability and relatively high strength Physical stabilization results (The bubbles are not
interconnected and do not coalesce )
Increasing the life of a foam cement job The flexibility of foamed cement.

7. Conclusion
❑ The new technology has proved to be the most efficient among other solutions used to mitigate
or eliminate mud losses during well drilling in the high permeable and weak formations in the
Gulf of Guinea, Volga-Ural region and geothermal wells in the central California.
❑ Foamed cement's tensile strength, ductility, and displacement properties have made it
especially useful in several zonal-isolation scenarios and generate substantial cost savings
over the lifetime of the well.
❑ Nonproductive time attributed to successfully foam squeezing was reduced by 78% when
compared to squeezing with conventional cements in geothermal-drilling in a field in central
California.
❑ Considering the fact that foam cementing reduces non-productive time by an average of 2
days compared to conventional cementing, approximately 1,248 hours of rig time were saved
on 26 jobs completed over 5 years (from 2013 to 2017), which translates into almost two years
of drilling without any mud losses for the operator.
❑ Overall operational execution and cement evaluation indicate that the foam squeeze operation
enabled successful drilling of the well.
❑ Foamed-cement squeeze is a viable technique to be implemented in geothermal drilling.
❑ The flexibility of foamed cement can help increase the life of a cement job by maintaining the
integrity of hydraulic bonds, preventing the formation of a micro annulus, and eliminating stress
cracking.

8. References
✓ D. Lovett, C. O. Co, R. Hernández, and L. Chandarjit, “Squeeze with Foamed
Cement Cuts Nonproductive Time in a Geothermal Well,” no. April, pp. 2–4, 2010.
✓ A. Fomenkov, I. Pinigin, V. Zyryanov, A. Fedyanin, and P. Orenburgneft, “SPE-
191507-18RPTC-MS Foam Cementing in the Volga-Ural Region : Case Study,” no.
October, pp. 15–17, 2018.
✓ O. Taiwo, J. Ogbonna, P. Studies, and P. Harcourt, “SPE 150767 Foam Cementing
Design and Application : A Cure for Low Gradient- Associated Problems in
Deepwater Operations in the Gulf of Guinea,” 2011.
✓ A. Anya, “SPE-190079-MS Lightweight and Ultra-Lightweight Cements for Well
Cementing - A Review,” no. April, pp. 22–27, 2018.
✓ N. G.-M. ¯dimurec, B. Paši´, P. Miji´, and I. Medved, “applied sciences Drilling
Fluid and Cement Slurry Design for Naturally Fractured Reservoirs,” 2021.