College ofPetroleum Engineering and GeosciencePetroleumEngineering DepartmentWell Completion- PETE (302) Enhanced Gas Well Extraction: Using Combined System of Foam & Gas Lift Term 171 Project ByMohammed SubahiID: 201505390Section #: 1 Instructor/ Dr.
RAHUL GAJBHIYE Submitted on 25/12/2017 Table 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 AbstractLiquid droplets that load in gas wells cause several serious issues. Tosolve these problems, different lifting method were developed.
Lifting systemthat are used now for horizontal gas well were originally developed for oilwells. Moreover, this research is targeted mainly toward gas well deliquification(remove liquid from wellbore or dewatering). IntroductionIn natural gas well, the produced gas particles are attached to a loadof liquid droplets (oil condensate or water). Moreover, the produced gas canlift liquid droplets to the surface at the early age of the production when thegas pressure is high enough to provide such critical velocity to carry theliquid to surface.
After period of production when the well become mature, an amount ofliquid that present inside the tubing along with gas produced result indisperse within gas that drag gas flow downward by gravity. Therefore, gasvelocity falls and leads to extra decreases in extracted liquid volume thatcause accumulation which rise the burden of the ability to carry up liquiddroplets, which lead to gather more liquid and extra builds up accumulation ofliquid that cause a reduction or complete stop of the gas production. Objective· To discuss the improvementin deliquification.· To discuss new designmethod.
MethodologyI collected the data for a research in Well completion course that isabout summarizing some latest improvement in the field. Moreover, I collecteddata using OnePetro website from different journals and SPE papers. DiscussionGas well deliquification or gas well dewatering is a method ofcompletion that used to get rid of liquid (oil condensate or water) that occurwith gas during production from gas well. To deliquefy liquid in well, thereare different possible solutions such as:· Natural flow.
· Removing hydrostaticbarrier using pump· Capillary string· Intermitting (cease theproduction for a time) · Rocking· Equalizing· Venting · Soaping· Velocity string· Compression· Gas lift· Beam lift· Plunger lift· Foam lift· ESP and HSP· PCP· Diaphragm pump· Jet pup In this research we will focus on foamer injection that is used toincrease gas production. The foam performance depends on different parameterssuch as pressure, temperature, hydrocarbon fraction, and foamer agitationvelocity. In addition, Foam Assisted Gas Lift may be used and it is consideredto bean economical choice due to its increased gas production rate and itrequires less injected gas. There are three types of tests that applies on foamto test its performance that are:· Foam buildup test· Collapse test· Liquid carryover testIn addition to that there are system consideration such as:· Cost of production andamount of pay· Solution life· CO2 and H2S corrosion· Acid resistant· Amount of water and theability to control it· The cause of condensation· The depth of condensation· Safety valve· The power required · The costs and risks ofworkoverThe gas velocity is affected by the design of the well bore (such assudden expansion/contraction).
Moreover, the gas condensate is affected by therate of production Slower velocity => poorer lift => longer transit time => moreheat loss => water condensate. Some of the methods are depend on recharging the well from nearformationRecharging from low permeability zones to higher permeable zoneMethod such as:· High permeability streaks· Natural fracture · Stimulated fracturesLiquid behavior is affected by the deviation of the well. Where in thevertical well, all the liquid droplets are lifted by flowing gas. However, in adeviated well, a separation is possible due gravity where liquid droplets willbe accumulating down hole A.
Gas LiftThe method of gas lift is used to improve the production rate and todeliquefy the gas well as an artificial lift technique by decreasing thehydrostatic pressure of the liquid. This method is applied by injecting highpressure 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 gaswell by decreasing the liquid surface tension and its density.
This methoddepends on injecting soap from surface in the tubing through capillary string.Moreover, the system components are:· Capillarysoap· Stainlesssteel capillary string· Foot valve(soap injection valve)· Capillaryhanger· Soap pump · Soap tank Andthe systematic process is: C. Foam Assisted Gas LiftIthybrid technique that use both Gas lift and Foam assisted lift to improve theeffectiveness of the two methods by injecting soap and gas. In other words, thesoap is increasing the liquid column and the injected gas energize the flow.
This method is most effective when:· The wellflow is very low, and much liquid was accumulated· The liquidcolumn is lower than gas valve. D. The study case This is an example of natural flow gas well that has been completedthree times after depletion: i. NaturalFlowThe cumulative production after perforation of Sand Y is around 18 MMMCFand around 1 MMSCFD initially that is increasing with time and loads in thetubing. After 8 years of production, the flow rate of gas fall to 1 MMSCF perday and the Water-Gas ratio was 300 STB/MMSCF. Therefore, Sand Z was perforatedto comminglally produce around 7 MMSCFD.
Moreover, wellhead gas compressionsystems was applied for 10 years to rise flow up to 12 MMSCFD and 30STBMMSCF ofWater-Gas ratio. In 2011, the was depleted due to loss of energy to flow thegas with around 57% recovery rate. ii. GasLiftThe Gas lift system was introduced in M-1 well in 2012 to deliquefy thegas well by inject 0.4 MMSCFD of gas the produced around 1.
7 MMSCFD and 225STBD of water. Shortly, the gas flow dropped to 1.2 MMSCFD with largerWater-Gas ratio that show liquid droplets are loading in the tubing. After 6Months, Gas lift system has produced only 1.6 BCF that is 2.4 % recovery.
iii. FoamAssisted LiftAfter Gas lift system was suspended, a Foam assisted lift was introducedin the gas well. Soap was injected close to the perforation using capillarystring. In the beginning of injection, Soap was injected at rate of ahalf-gallon per day and raised gradually to a rate of 5 gallons per day thatresult in 1.5 MMSCFD of gas.
However, any further increment of injected soapleads to drop in the production rate. After three months, a liquid dropletsload occurs and requires gas lift to provide sufficient energy to flow the gaswell. Therefore, new lifting system were introduced in the well. One oflimitation of foam that is affected by temperature. iv. FoamAssisted Gas LiftAfter 5 months in 2013, a combined system of Gas lift and Foam assistedlift was applied to dissolve the liquid loading of the gas well.
In fact, itwas a challenge to determine the optimum rate of soap and gas injection rate atthat time because there were no standard values for this combined system.Therefore, several trial and error were applied and the best values for M1 wellwere 2 Gallon per day of soap and 0.3 MMSCFD of injected gas. After 21 days ofinstable production, the production stabilizes at 1.3 MMSCFD with 300 BBL ofwater per day.
Conclusion· It is advantageous to use acombined system of Gas lift and Foam assisted lift that optimize productionrate of gas well and overcomes limitation of two methods alone.· Soap injection has anoptimum rate; any variation affects the production negatively.· High temperature reduce theeffectiveness of Foam performance. References Tayyab, I.
, Uddin, M. F., Ahmed, Q. I., Ibad-Ur-Rehman, M.
, & Azam,Q. S. (2016). Combination of Foam Assisted Lift & Gas Lift (FAGL) toDe-liquefy Gas Wells. SPE/IADC Middle East Drilling Technology Conference andExhibition.
doi:10.2118/178259-msWilson, A. (2017). Artificial-Lift-System Selection Guidelines forHorizontal Gas Wells. Journal of Petroleum Technology, 69(07), 61-62.doi:10.2118/0717-0061-jpt
