John Rhoads Ranette Halverson Nelson L. Passos
Department of Physics Department of Computer Science Midwestern State University
Computerized Analysis of Flowing Conditions for Use of Chemical Sticks in
Natural Gas Wells
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Outline• Oil field applications
• Chemical sticks
• Required field computation
• Results
• Summary
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OIL FIELD COMPUTER APPLICATIONS
•STRUCTURAL DESIGN (OFFSHORE PLATFORMS)
•RESERVOIR SIMULATION
•SEISMIC ANALYSIS
•FUTURE PRODUCTION FRECASTS
•FINANCIAL MANAGEMENT
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OIL FIELD COMPUTER APPLICATIONS
USUAL REQUIREMENTS:
•SUPERCOMPUTERS
•PARALLEL SOFTWARE
•HIGH COSTS
•REMOTE DATA PROCESSING
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OIL FIELD COMPUTER APPLICATIONS
SMALL SOFTWARE TOOLS:
•directional/horizontal drilling•water and CO2 flood prediction•tubing and casing design routines•tubular inventory•analysis of geological features• risk analysis
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THE CHEMICAL STICK PROBLEM
WELL-KNOWN PROBLEMS:
• Internal corrosion of tubular products
• Corrosion results cessation of production
• Liquid chemical treatments cannot be dumped
down tubing in a flowing gas well
• Liquid treatment requires shut down of
production operations
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THE CHEMICAL STICK PROBLEM
PROCEDURE:
• Delivery of chemicals to the bottom of hole is made by
dropping a solid chemical stick inside the tubing
• Stick designed to fall to the bottom of the hole, become
static, slowly dissolving over time to release active
corrosion control ingredients
• Question? whether or not a given size
chemical stick will fall in a gas stream
flowing inside a tube
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FIELD COMPUTATION
INPUT:
• Flow rate from the well
• Wellhead pressure
• Chemical stick falls under the influence of gravity
REQUIRED:
• Impulse of gas stream incident on and normal to the
cross sectional area of the bottom of the chemical stick.
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FIELD COMPUTATION
CALCULATIONS:
• Assumptions were required due to lack of information
on frictional data (dragging forces), bottom hole
pressure, heat exchange (gas and environment), etc.
REQUIRED ANSWER:
• Will the stick fall to the bottom?
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SOLUTION
StickDrop AlgorithmEstimate flowing bottom hole pressureEstimated bottom hole temperatureCalculate the gas density at the bottom hole Compute the mass flow rate MFR (lbs/second)Calculate the velocity in feet per secondCompute force per second impact on end of stick:Calculate the mass Calculate the buoyancy If weight is greater than the impulse force, the stick will drop. END
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EXPERIMENTAL DATA
Tubing dimensions
Tubing Area (square inches)
1.90" 2.138
2.375" 3.272
2.875" 4.680
Chemical stick dimensions
Stick Area Length Weight (lbs)
1.00" 0.785 15 0.55
1.25" 1.227 15 0.75
1.625" 2.074 18 1.50
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EXPERIMENTAL DATA1.
90"
A 2.138 sq in
Tubing
1.00"
Chemical Stick
90° F
Bottom hole temperature
Flow rate = 5,000 Mcfd(million cubic feet/day)