Introduction to Petroleum Production and Optimisation

8/9/2019 Introduction to Petroleum Production and Optimisation

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Semester January 2015, Credit hour 3Duration 14 weeks Lecture + 2 Weeks Study & Exam

Lecture 30 hours + Lab/Tutorial 24 hours

InstructorDr. Mohammed MahbuburRahman

1. Beggs H.(2003), Production Optimization Using NODAL Analysis, Second Edition, OGCI2. Economides M. et al. (1994), Petroleum Production Systems, Prentice-Hall Inc.3. Michael Golan and Curtis H. Whitson (1991), Well Performance, 2nd Edition, Prentice-Hall

Course ContentReservoir Performance

Well Performance Equations, Darcy’s Law Factors affecting productivity indexIPR for oil and gas wellsBack pressure equations

Well Completion effectsFlow in Pipes and Restrictions

Energy equation, single and multi-phase flowsFluid Property calculations

Well flow correlations:Hagedorn and BrownPoettmann and CarpenterDuns and RosOrkiszewski

Aziz, Govier and FogarasiPipe flow correlationsPressure drop through restrictions

Total System AnalysisTubing and Flow line size selectionSystem analysis for wells with restrictionsEvaluating Completion effectsNodal analysis of injection wellsEffect of depletionRelating performance to time

Analyzing multiwell systems Artificial Lift Design

Continuous Flow Gas liftElectrical Submersible Pump (ESP) selectionSucker rod / beam pumpingHydraulic pumping


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Learning Outcome At the end of the course, students should be able to:

1. Apply fundamentals of production optimization usingcommercial software.

2. Analyze the performance of the petroleum productionsystem.

3. Understand the interaction of the reservoir system and

its effect on the overall production system.4. Design optimum petroleum production systems.

Lecture OutlineDefinition of OPTIMIZATIONOPTIMIZATION vs MAXIMIZING/MINIMIZINGOptimization in Oil Production ContextProduction System Design ChallengesLecture Summary


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an act, process, or methodology of making something (as a design, system, or decision) as fullyperfect, functional, or effective as possible; specifically : the mathematical procedures (as findingthe maximum of a function) involved in this (Webster)

Definition of OPTIMIZATION

• Finding an alternative with the most cost effective or highest achievable performance underthe given constraints, by maximizing desired factors and minimizing undesired ones.

• In comparison, maximization means trying to attain the highest or maximum result oroutcome without regard to cost or expense .

• Practice of optimization is restricted by the lack of full information, and the lack of time toevaluate what information is available

• In computer simulation(modeling) of business problems, optimization is achieved usually

by using linear programming techniques of operations research.• to find the best compromise among several often conflicting requirements, as in engineering

design

OPTIMIZATION vs MAXIMIZING/MINIMIZINGOPTIMIZATION does not mean MAXIMIZINGThe goal of optimization may be Maximizing or MinimizingSuppose we want to MAXIMIZE something (such as production, or revenue, or profit, -any one of these, some times refered to as the object fuction )That ’ something ’ may depend on any number of variables

We adjust these variables in a manner so that ’something ’ is maximized

This process is called OPTIMIZATIONOPTIMIZATION may be performed to MINIMIZE something as well (such asminimizing noise, vibration, friction losses, flaring, water cut, etc.)

The related variables cannot be adjusted at will, however. They are subject to variousconstraints.


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Example: Optimal Design of a CanStep 1: Project/Problem Statement The purpose of thisproject is to design a can to hold at least 400 ml of liquid,as well as to meet other design requirements (1 ml = 1cm3).The cans will be produced in the billions so it is desirableto minimize manufacturing costs. Since cost can bedirectly related to the surface area of the sheet metal, it isreasonable to minimize the amount of sheet metalrequired to fabricate the can. Fabrication, handling,aesthetics, and shipping considerations impose thefollowing restrictions on the size of the can:the diameter should be no more than 8 cm and no lessthan 3.5 cm, whereas the height should be no more than 18cm and no less than 8 cm.Step 2: Data and Information Collection Given in the projectstatement.Step 3: Identification/Definition of Design Variables Thetwo design variables are definedD = diameter of the can, cmH = height of the can, cm

Step 4: Identification of a Criterion to Be Optimized Thedesign objective is to minimize the total surface area S ofthe sheet metal for the three parts of the cylindrical can:the surface area of the cylinder (circumference X height)and the surface area of the two ends.Therefore, the optimization criterion or cost function (thetotal area of sheet metal), is written as:

Step 5: Identification of Constraints The first constraint isthat the can must hold at least 400cm3 of fluid, which is

written as:

Goal of the optimization exercise here is to find which values of D and H will yield the MINIMUM value of S, while meeting this criteria

Optimization in Oil Production ContextLet us consider a single well.production invloves many factors such as:

Ability of reservoir to flow (Reservoir pressure, permeability, bottomhole pressure etc)Capacity of production string or tubingCapacity of seperator, and process plant

Water cut, Water handling facility Oil price, etc

What are we trying to Maximize?Let us say, we want to maximize oil production rate.This is our objective function.

All other related parameters (such as tubing size, bottom hole and well head pressure,flow line, separator, etc.,) should be adjusted in a way so that we obtain maximum oilrate. This process is OPTIMIZATION.


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Optimization in Oil Production Context..Therefore, we need a sound understanding of the petroleumproduction system, and how each component of the system interact with one another, and ultimately affect the production rate.The functions of each major component, and its effect on the overallproduction, will be studied throughout the course. After learning about individual components, we will look at the entiresystem, and familiarize with the «Total System» conceptSince optimization involves working with many components/variables,it requires computer programingCommercial software for production optimization will be introduced

• Major segments of theproduction system

• Reservoir (InflowPerformance Relationship)

• Wellbore (Completions,Tubing etc)

• Surface Facilities (Flowlines, Separator, Pipelines

etc)

• Any one of these canadversely affect our target – to’maximize oil rate’

Next, let us look at the simplified production system


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Production System Design ChallengesSuppose a discovery is made, and initial studiesindicate high potential for oil/gas production

Some common questions/challenges to theengineer(s):

What is the behavior of the reservoir andfluid(s)

Kh, k, s, average reservoir pressureFluid properties, GOR, WOR, GLR, Bubble pointpressure, etcIPR, factors affecting IPR Is stimulation necessary?

What type of completion should be usedSingle/duel/slotted liner/open hole/gravel pack/perfetc

What should be the tubing sizeToo large tubing may cause liquid loading andinterrupted productionToo small tubing will incur high energy loss andrestrict production

Will phase separation occur along the tubing?

What should be the tubing head/bottom

hole pressuresHigh PI is desirabletoo much draw down is not good- sanding, coningetc may take place

What should be the separator size andpressure

Single stage vs multi stage, separator capacity- largeseparator may be under-utilized for most part of welllife

What should be the flow line size andconfiguration Water and gas handling facilities What will be the role and effect of valvesand chokes setting? Will any artificial lift be necessary (if not atthe outset, but at later life of the well)

Now, relate these questions to our course content. Make sense?

Lecture Summary Optimization does not mean MaximizingOptimization involves working with mutiple variablesGoal of optimization is to maximize/minimize a pre-determinedobjectiveProduction system consists of many componentProduction optimization therefore is the process of studying theeffect of each component and adjusting them to achieve adesired effect, such as

Maximizing production rate/revenue/profit/life of well/PI, etc.Minimizing pressure losses, f laring, etc.

Introduction to Petroleum Production and Optimisation

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