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College of
Petroleum Engineering and Geoscience

Engineering Department

Well Completion
- PETE (302)



Enhanced Gas Well Extraction:

 Using Combined System of Foam & Gas Lift


Term 171 Project



Mohammed Subahi

ID: 201505390

Section #: 1


Instructor/ Dr. RAHUL GAJBHIYE


Submitted on 25/12/2017





of Contents
Abstract 1
Introduction. 1
Objective. 2
Methodology. 2
Discussion. 2
A.                   Gas Lift 4
B.                   Foam Assisted Lift 4
C.                   Foam Assisted Gas
Lift 4
D.                   The study case. 4
i.                               Natural
Flow: 4
ii.                               Gas Lift: 4
iii.                              Foam
Assisted Lift: 4
iv.                              Foam
Assisted Gas Lift: 4
Conclusion. 4
References. 4



Liquid droplets that load in gas wells cause several serious issues. To
solve these problems, different lifting method were developed. Lifting system
that are used now for horizontal gas well were originally developed for oil
wells. Moreover, this research is targeted mainly toward gas well deliquification
(remove liquid from wellbore or dewatering).




In natural gas well, the produced gas particles are attached to a load
of liquid droplets (oil condensate or water). Moreover, the produced gas can
lift liquid droplets to the surface at the early age of the production when the
gas pressure is high enough to provide such critical velocity to carry the
liquid to surface.

After period of production when the well become mature, an amount of
liquid that present inside the tubing along with gas produced result in
disperse within gas that drag gas flow downward by gravity. Therefore, gas
velocity falls and leads to extra decreases in extracted liquid volume that
cause accumulation which rise the burden of the ability to carry up liquid
droplets, which lead to gather more liquid and extra builds up accumulation of
liquid that cause a reduction or complete stop of the gas production.



To discuss the improvement
in deliquification.

To discuss new design





I collected the data for a research in Well completion course that is
about summarizing some latest improvement in the field. Moreover, I collected
data using OnePetro website from different journals and SPE papers.









Gas well deliquification or gas well dewatering is a method of
completion that used to get rid of liquid (oil condensate or water) that occur
with gas during production from gas well. To deliquefy liquid in well, there
are different possible solutions such as:

Natural flow.

Removing hydrostatic
barrier using pump

Capillary string

Intermitting (cease the
production for a time)





Velocity string


Gas lift

Beam lift

Plunger lift

Foam lift



Diaphragm pump

Jet pup


In this research we will focus on foamer injection that is used to
increase gas production. The foam performance depends on different parameters
such as pressure, temperature, hydrocarbon fraction, and foamer agitation
velocity. In addition, Foam Assisted Gas Lift may be used and it is considered
to be
an economical choice due to its increased gas production rate and it
requires less injected gas. There are three types of tests that applies on foam
to test its performance that are:

Foam buildup test

Collapse test

Liquid carryover test

In addition to that there are system consideration such as:

Cost of production and
amount of pay

Solution life

CO2 and H2S corrosion

Acid resistant

Amount of water and the
ability to control it

The cause of condensation

The depth of condensation

Safety valve

The power required

The costs and risks of

The gas velocity is affected by the design of the well bore (such as
sudden expansion/contraction). Moreover, the gas condensate is affected by the
rate of production

Slower velocity => poorer lift => longer transit time => more
heat loss => water condensate.


Some of the methods are depend on recharging the well from near

Recharging from low permeability zones to higher permeable zone

Method such as:

High permeability streaks

Natural fracture

Stimulated fractures

Liquid behavior is affected by the deviation of the well. Where in the
vertical well, all the liquid droplets are lifted by flowing gas. However, in a
deviated well, a separation is possible due gravity where liquid droplets will
be accumulating down hole







A.     Gas Lift

The method of gas lift is used to improve the production rate and to
deliquefy the gas well as an artificial lift technique by decreasing the
hydrostatic pressure of the liquid. This method is applied by injecting high
pressure gas in the well pipe through valves on the annulus string. 

B.     Foam Assisted Lift


Foam assisted lift is a new technique that is used to dewater the gas
well by decreasing the liquid surface tension and its density. This method
depends on injecting soap from surface in the tubing through capillary string.
Moreover, the system components are:


steel capillary string

Foot valve
(soap injection valve)


Soap pump

Soap tank



the systematic process is:












C.     Foam Assisted Gas Lift

hybrid technique that use both Gas lift and Foam assisted lift to improve the
effectiveness of the two methods by injecting soap and gas. In other words, the
soap is increasing the liquid column and the injected gas energize the flow.
This method is most effective when:

The well
flow is very low, and much liquid was accumulated

The liquid
column is lower than gas valve.




D.     The study case


This is an example of natural flow gas well that has been completed
three times after depletion:




The cumulative production after perforation of Sand Y is around 18 MMMCF
and around 1 MMSCFD initially that is increasing with time and loads in the
tubing. After 8 years of production, the flow rate of gas fall to 1 MMSCF per
day and the Water-Gas ratio was 300 STB/MMSCF. Therefore, Sand Z was perforated
to comminglally produce around 7 MMSCFD. Moreover, wellhead gas compression
systems was applied for 10 years to rise flow up to 12 MMSCFD and 30STBMMSCF of
Water-Gas ratio. In 2011, the was depleted due to loss of energy to flow the
gas with around 57% recovery rate.


The Gas lift system was introduced in M-1 well in 2012 to deliquefy the
gas well by inject 0.4 MMSCFD of gas the produced around 1.7 MMSCFD and 225
STBD of water. Shortly, the gas flow dropped to 1.2 MMSCFD with larger
Water-Gas ratio that show liquid droplets are loading in the tubing. After 6
Months, Gas lift system has produced only 1.6 BCF that is 2.4 % recovery.






Assisted Lift

After Gas lift system was suspended, a Foam assisted lift was introduced
in the gas well. Soap was injected close to the perforation using capillary
string. In the beginning of injection, Soap was injected at rate of a
half-gallon per day and raised gradually to a rate of 5 gallons per day that
result in 1.5 MMSCFD of gas. However, any further increment of injected soap
leads to drop in the production rate. After three months, a liquid droplets
load occurs and requires gas lift to provide sufficient energy to flow the gas
well. Therefore, new lifting system were introduced in the well. One of
limitation of foam that is affected by temperature.



Assisted Gas Lift

After 5 months in 2013, a combined system of Gas lift and Foam assisted
lift was applied to dissolve the liquid loading of the gas well. In fact, it
was a challenge to determine the optimum rate of soap and gas injection rate at
that time because there were no standard values for this combined system.
Therefore, several trial and error were applied and the best values for M1 well
were 2 Gallon per day of soap and 0.3 MMSCFD of injected gas. After 21 days of
instable production, the production stabilizes at 1.3 MMSCFD with 300 BBL of
water per day.



It is advantageous to use a
combined system of Gas lift and Foam assisted lift that optimize production
rate of gas well and overcomes limitation of two methods alone.

Soap injection has an
optimum rate; any variation affects the production negatively.

High temperature reduce the
effectiveness of Foam performance.




Tayyab, I., Uddin, M. F., Ahmed, Q. I., Ibad-Ur-Rehman, M., & Azam,
Q. S. (2016). Combination of Foam Assisted Lift & Gas Lift (FAGL) to
De-liquefy Gas Wells. SPE/IADC Middle East Drilling Technology Conference and
Exhibition. doi:10.2118/178259-ms

Wilson, A. (2017). Artificial-Lift-System Selection Guidelines for
Horizontal Gas Wells. Journal of Petroleum Technology, 69(07), 61-62.