CGE 654 week 1

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Wellbore Completion Conceptsand Designs

Faculty of Chemical Engineering

CGE 654Well

Completion

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E-Books

1. Petroleum Engineering Handbook - Howard B. Bradley2. Petroleum Production Systems – Prentice Hall3. Production Operations – Volume 1 & 2 (Well Completion,

Workover & Stimulation)

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Course Learning Outcomes :

• Define well completion

• Define the objectives of well completions

• Describe the factors affecting well completions

• Recognize many types of well completions

• To identify and describe functions of well completion componentsand equipment

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Well Completion:

Definition:

Thedesign

,selection

andinstallation

of tubulars

,tools

andequipment located in the wellbore for the purpose of conveying , pumping or controlling production or injection

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Well Completion:Design and completion objectives(production and injection wells)

1. Provide communication between the reservoir & thewell

2. Provide optimum production/injection performance3. Ensure safety – safe for production oil e.g. to control

sand production. Unconsolidated?consolidated?4. Maximise the integrity and reliability of the completion

over the completed well life5. Minimise the total costs per unit volume of fluid

produces or injected

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Well Completion : Design Criteria & ProcessThe well is

drilled TOP toBOTTOM

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http://slidepdf.com/reader/full/cge-654-week-1 7/29Faculty of Chemical Engineering

The well isdrilled TOP to

BOTTOM

Well Completion : Design Criteria & Process

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BOTTOM

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BOTTOM

IDProd Casing

IDTubing

But, isdesigned

BOTTOM toTOP

Production packer

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Factor affecting well completion design

Ideal completion design – the lowest cost completion (consideringinitial and operating costs) that meets (nearly meets) the demandsplaced upon it for most of its life.

Estimate the producing characteristics during the life of the wellmust be made.

Both reservoir and mechanical considerations must be evaluated

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Elements of Well Completion Design

Elements

MechanicalConsideration

ReservoirConsideration

Method of Well

Completion

Type of WellCompletion

SpecialStudies

Requirement

Design DataRequirement

DesignProcess

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1. Reservoir considerationsinvolve the location of various fluids in the formations penetrated by thewellbore, the flow of these fluids through the reservoir rock, and thecharacteristics of the rock itself • Producing rate

- Provide maximum economic recovery- Starting point for well completion design- Determine the size of production conduit

• Multiple reservoir

- Multiple completions in one drilled hole- Possible problemsMultiple completions inside casing separated by packersCommingling of hydrocarbons from separate reservoirsdownholeDrilling several boreholes from one surface location

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1. Reservoir considerations (cont.)• Reservoir drive mechanism

determine whether completion interval will have to be adjusted as gas-oilor water-oil contacts move

- Water drive - indicate water production problems- Dissolved gas drive – indicate artificial lift- Dissolved gas and gas drive – declining productivity index and

increasing gas-oil ratio• Secondary recovery

Require a completion method conducive to selective injection orproduction- Water flooding – increase volumes of fluid to be handled- High temperature recovery process – require special casing and

casing cementing materials

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1. Reservoir considerations (cont.)• Stimulation

- Require special perforating patterns to permit zone isolation- Able to adapt with high injection rate

- High temperature stimulation require special cementing procedures,casing and casing landing practices

• Sand control- Dictate type of completion method and maximum production rates- Reservoir fluid control problems dictate that a less than desirable

type of sand control be used- Sand problem zones always dictate a payoff from careful wellcompletion practices

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1. Reservoir considerations (cont.)• Workover frequency

- Probably high due to several reservoirs must be drained through onewellbore

- Dictate a completion conducive to wireline or through-tubing typerecompletion systems

• Artificial lift- Single completions even where multiple zones exist (larger than

normal tubular)

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2. Mechanical Considerationsknown as “well hook -up”; key to being able to deplete the reservoireffectively, monitor downhole performance, and modify the well situationwhen necessary

Well completion design (mechanically) – complex engineering problemBasic philosophy – to design to specific well conditions, field conditions andarea condition

• Maximize profit

- Provide maximum economic recovery• Keep the installation simple- Multiple completions in one drilled hole

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2. Mechanical Considerations (cont.)• Overall reliability

- Provide maximum economic recovery• Anticipate all operating conditions

- Multiple completions in one drilled hole- Possible problems

• safety

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Completion Techniques

1. Open hole completionSimplest & cheapest completion (noequipment requires to be installed)Not recommended for production orinjection wellIf water/gas breakthrough or migrationinto the wellbore occurs it is difficult toisolate unless the entry (at the baseisolated with cement plug)

Drawback – all zones open to flow, nocontrol

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1. Open hole completion (cont.)Borehole may become unstable – collapseor formation @ production of sand mayoccurOpen hole only applied in consolidatedformation in a range of environment;a. Low cost / multi well developmentsb. Deep wells, consolidated with

depletion drive

c. Naturally fractured reservoird. Some horizontal and multi lateral

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2. Screen or Pre-slotted Liner CompletionsOnce drilling through is completed – wire-wrapped screen/steel pipe (hasslots)/alternative sand control screenwill be installedPrincipal purpose – to prevent anyproduced sand from migrating withproduced fluids into production flowstring

Success of completion in controllingsand production – depend on screen orslot sizes and the sand particles sizesBut slots may quickly become pluggedand impede flow resulting - loss in

productivity

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2. Screen or Pre-slotted Liner Completions(cont.)

Sometimes system used ininclined/high angle to prevent majorborehole collapse or facilitate thepassage of logging toolsLow cost technique (cost of a screen tocover the reservoir interval <cost of acasing string run to surface & cost of

cementing and perforating) Drawback – all zones open to flow, nocontrol

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2. Screen or Pre-slotted Liner Completions(cont.)

Application - control production of formation particles from weakerformations:

Reservoir with large &homogeneous sand grainsSome horizontal & multilateralwells

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3. Cemented and Perforated Casing/LinerCommon type of completionInstall either a casing string (extend backto surface) @ a liner (extend back intothe shoe of the previous casing string)Cemented in place by the displacementof a cement slurry into annular spacebetween the outside wall of casing andthe borehole wall

Casing and cement sheath will beperforated at selected locations usingexplosive charges contained in aperforating gunProvide flow paths for fluid to enter the

wellbore from formation @ vice versa

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3. Cemented and Perforated Casing/Liner(cont.)

Effective completionhydraulic seal being located in thecasing-formation annulus by thecementSuccess primary cement job – provide zonal isolation behind casing

Failure of cement – lead to fluid

migration behind casing to surface intoanother zone

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Involves greater costs and timeFull length of casing (from surface tothe base of well)Cost of perforating, cementing andadditional time to complete theboreholeUse of liner – reduce the required

length of tubular & overall cost

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Ability – Control depletion of individual zonesIsolate the inflow of undesirableproduced fluidsControl the injection of fluids intozones are essential to a largenumber of development

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Open Hole Gravel PackOpen Hole

PerforatedCasing

PerforatedLiner

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Special Study Requirement

• PVT• Core Analysis• Metallurgy• Formation Water/Crude Analysis

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Completion ProcessReservoirReservesPressure

FluidsSaturations

Characteristics

RockZonesProperties

EconomyRevenuesExpenses

FDPNb of WellsArchitectureProd Rates

+Well ConstructionWell TypeMudDrilling particularsCasingsTubing SizeCementing

Well CompletionCompletion FluidPerforationsArtificial LiftCompletionAccessories

Sand ControlStimulation

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