A Web-Based Platform for Solution of Generalized Gas-Lift Optimization Problems

STUDENT PRESENTATION CONTEST 2005

STUDENT CHAPTER OF CAMPINAS

A Web-Based Platform for Solution of Generalized Gas-Lift Optimization Problems

Augusto M. de Conto



Summary

• Generalized lift-gas allocation problem

• Effective mixed-integer formulations

• State-of-the-art algorithms

• User-friendly web interface



New Field

Reservoir

Oil + Gas + Water

Separator

Tubing

Casing



Mature Field

Reservoir

Separator

Tubing

CasingOil + Gas + Water



Artificial Lift

•Beam Pump

•Electric Submersible Pump

•Gas Lift



Gas Lift

• High pressure gas is inject into the production tubing

• Reduce the density of fluid column

• Stimulates natural flow



Well Performance Curve (WPC)

33

2210 iiip qaqaqaaq

)1ln(42

321 iiip qcqcqccq

ii qqp eeq 21

21 )2(

• Polynomial

• Alarcón et al. (2002)

• Nakashima et al. (2005)



WPC Piecewise Linear Formulation



Typical Gas Lift Objectives

• Production maximization

• Profit maximization

• Cost minimization subject to production quota



Gas Lift Field



Typical Gas Lift Constraints

• Limited lift-gas injection rate




• Limits on oil, gas and water handling capacities




• Different gas-lift performance curves for each well

• Lower and upper bounds on gas-lift injection• Activation constraints



Objective Function

• N: number of wells

• po, pg: profit per produced barrel of oil and gas

• pw,pi: water treatment and gas compression cost

• γon, γg

n, γwn: fractions of oil, gas and water produced by well n

• qpn: production rate of well n

• qin: gas injection rate for well n

N

n

nii

np

nww

ngg

noo qpqpppf

1

max



Facility Constraints

N

ni

ni qq

1

max Available gas injection rate

• Compressor capacity



Facility Constraints

N

nsep

np qq

1

max

N

noil

np

no qq

1

max

N

nwater

np

nw qq

1

max

N

ngas

np

ng qq

1

max

Total separation capacity

Oil handling limit

Water handling limit

Gas handling limit

• Separator capacity

1 nnn

wgo



Precedence Constraint

)(,, GEjiyy ji

1

2

4 5

3

6

7

8 9



Our Contribution

P5(G)

Objective

Multiple facilityconstraints

Precedenceconstraint



Our Contribution

P5(G)

P5(ø)MILP

• Multiple facility constraints• No precedence



Our Contribution

P5(G)

P1(G) P5(ø)MILP

• Compressor capacity constraint• Precedence constraint



Our Contribution

P5(G)

P1(G)

P(ø)DP

MILP

P(F)DP

MILP

P(G)DP

MILP

P5(ø)MILP

currentresearch



Web Based Interface

• Interface that allows user to specify information about the well field and run optimization algorithms

• Need of an environment to call optimization algorithms– Friendly– Transparent– Expansible



Interface Structure

User localinterface

User localinterface

Optimizationserver

Optimizationserver

local remote

WebWeb



Local

• Well field specification

• Automatically converts optimization models

• Operational System free

User localinterface

User localinterface

local



Remote

• Run optimization algorithms

• Heavy algorithms requires high memory and processing capacity

• Usage of non freeware optimization tools

Optimizationserver

Optimizationserver

remote



Interface



Bibliography

• G. A. Alarcón, et al.: “Global Optimization of Gas Allocation to a Group of Wells in Artificial Lift Using Nonlinear Constrained Programming”, ASME Journal of Energy Resources Technology, 2002

• P. Nakashima, et al. “Optimization of Lift-Gas Allocation Using Dynamic Programming”, Accepted to appear in IEEE Transactions on Systems, Man and Cybernetics, Part A, 2005



A Web-Based Platform for Solution of Generalized Gas-Lift Optimization Problems

Augusto M. de Conto

Thank you!

A Web-Based Platform for Solution of Generalized Gas-Lift Optimization Problems

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