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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IMPLEMENTATION

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IMPLEMENTATION

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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)

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EXPERIMENTAL DATA

Chemical stick not heavy enough

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~ Summary ~

• Computer applications availability

• Field operation requirements

• Computerized solution for the chemical stick drop

• Benefits of a field solution

Questions??