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Experimental Study on Foam Flow Semi-Annual Meeting. Ayantayo Ajani The University of Tulsa. Outline. Introduction Objectives Experiments & Procedures Test Matrix Experimental Observation Current Work Timeline. Introduction.
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Experimental Study on Foam FlowSemi-Annual Meeting Ayantayo Ajani The University of Tulsa
Outline • Introduction • Objectives • Experiments & Procedures • Test Matrix • Experimental Observation • Current Work • Timeline
Introduction • Accumulation of formation water, condensed water or hydrocarbon condensate at the bottom of a well can cause decline in reservoir pressure and this will result in decline in gas well’s production rate • Chemical foamers are used as a means of artificial lift to enhance the productivity of gas wells
How Do Surfactants Work? • Foam consist of small bubbles surrounded by thin liquid film • The foam structure has a reduced gravitational gradient due to high gas holdup • The slippage between gas and liquid under foam conditions is reduced.
Desirable Characteristics • Stability – should be stable with little agitation; however, cannot be too stable so that it cannot be separated at separator • Flexibility & Tolerance – should create foam at varied conditions – different concentrations of brines and various temperatures • Concentration – should be effective at low concentration to be cost effective
Objectives • To build an experimental facility that will be used to study the foaming ability and unloading potential of surfactants. • To define appropriate measurement parameters for foam stability which will capture foam behavior as desired in gas wells
Objectives • To investigate different foaming agents’ liquid unloading potential at different surfactant concentrations, temperatures, and formation brine compositions. • To develop a model which will utilize the transient data in small scale facility (foam height vs. time, liquid collected vs. time) to predict the behaviour in gas wells.
Objectives • To use stability and unloading rig test to evaluate efficacy of foamers (Bench Top Test) • To extrapolate results from above in studying surfactant effect on pressure gradient and liquid holdup in 2-in and 4-in vertical pipes (Large scale test)
Outline • Introduction • Objectives • Experiments & Procedures • Test Matrix • Experimental Observation • Current Work • Timeline
Experiments : Recap of Last ABM • Bench Top Tests: • Surface Tension Test • Unloading Test • Stability Test • Large Scale Test
Unloading Test • Features • Filtered compressed air at 18psi • Porous ceramic disc • Heating jacket • Weighing scale connected to PC
Procedure - Liquid Unloading • Weigh surfactant, mix with deionized water, stir for 20 minutes, avoid foaming • Prewash column with test solution, pour solution into the column using a funnel with hose • Start balance and video recorder • Introduce air at desired rate for 30 minutes • Monitor height decrease while sparging with camera
Procedure - Liquid Unloading • Wait until liquid level in the pan on the scale stops rising • Wash the cell with soap solution, wipe with acetone and dry with air
Data Gathered - Liquid Unloading • The unloading rate is reported as the percent of liquid transferred at 10 minutes after the test is started. X 100
Stability Test • Features • Modifications of the unloading rig • Unloading facility was used to conduct stability test • Stability and Unloading tests have similar foam quality
Procedure – Stability Test • 100ml of surfactant and DI water is placed in test cell and sparged till entire solution is foamed • Maximum height of foam generated is recorded visually when sparging is stopped • Liquid draining from foam is recorded with a camera for 20 minutes • Height of draining foam is recorded visually every minute
Data Gathered at Varying Concentration - Stability Test • Drained volume with time • Volumetric rate of liquid drainage, • Static foam height, (@ t = 0, secs) • Half life – time to recover 50% of initial liquid • Liquid holdup in remaining foam volume with time • Volumetric rate of foam formation, • Volumetric rate of foam decay,
Large Scale Facility – Initial Design (After Anton Skopich) • Facility Design • Flow Diagram • Structure • Mixing Section • Test Sections • Instruments • High speed video • Holdup measurements and verification • Modifications to the facility
Test Section • 3 Trapping Sections • 2 Quick Closing Valves • 2 Pressure Transducers • Visualization Box
Modifications to Large Scale Facility • To improve precision of gas and liquid flowrates: • Pressure regulator • New liquid pump
Outline • Introduction • Objectives • Experiments & Procedures • Test Matrix • Experimental Observation • Current Work • Timeline
Experimental Observation : Volumetric Rate of Foam Formation & Decay, (mL/secs)
Experimental Observation : Stability Test (S2557) • Air rate driven: • 0.75 & 0.80 LPM vs 0.35 & 0.40 LPM • Enhance dilution: • 100 of 10,000 mL vs 100 of 1000 mL • Concentration lower limit • <300 ppm – 100 mL cannot be sparged fully
Experimental Observation : Volumetric Rate of Foam Formation & Decay, (mL/secs)
S-2158: Effect of Brine & Temperature on Volumetric Rate of Foam Formation
S-2158: Effect of Brine & Temperature on Volumetric Rate of Foam Decay