4.drilling equipment firstpart

Instituto Superior TécnicoUniversidade de Lisboa

Masters in Petroleum Engineering 2014-2015

Drilling Engineering Course

José Pedro Santos Baptista

Mining and Geological Engineering Msc.Petroleum Engineering Msc.

Drilling Engineering Course

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4. Drilling Equipment

Casing

Tubulars, Mud, and Cement

Drill Bit

Characteristics and Types

Drill String

Components, BHA Design

Drilling Engineering Course 2014-2015 Masters in Petroleum Engineering


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Mechanics (Steel)


Stress and Strength

Stress = Load divided by the cross-sectional area where the load is applied

Strain and Stretch

Strain = Stretch divided by original Length

Young Modulus

E = Stress divided by Strain


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Mechanics (Steel)


Elastic limit

Limit beyond which, when stress is removed, the steel will have acquired a permanent stretchMinimum Yield Stress

The stress which gives a strain of 0.5%. When stress is removed, the steel will have acquired 0.2%of permanent deformationUltimate Tensile Stress

The maximum stress on the curve, very close to the stress which will cause steel failure


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Steel Properties


Yield Strength

The level at which the material changes from predominantly elastic to predominantly plasticstrain behaviour (psi)

Tensile Strength

The highest stress level a material achieves before it fails (breaks) (Lbs)


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Casing


Functions of Casing

Provide structural integrity to the well

Control troublesome zones (over-pressured, weak and fractured formations,unconsolidated, etc…)Prevent cave-ins

Isolate porous formations (different fluid pressure regimes) allowing drilling and production

Allow selective communication between the formations and the well

Cover up problems in existing casing


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Casing


Functions of Casing (Cont.)

Serve as a high-strength flow conduit from reservoir to surface both for drilling and productionfluids

Prevent near surface fresh water zones from contamination (reservoir fluids and drilling fluids)

Provide connection and support of the wellhead equipment and blow out preventers

Provide exact dimensions for running testing, completions and production subsurface equipment


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Casing


Functions of Casing (Cont.)

All Casing shall be designed to withstand all loads that can be imposed on them during installation and the lifetime of the well

No well construction program should be put forward without an approved casing design


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Casing


Casing Types

Cassion Pipe

(not mandatory)

(Offshore) Driven into the sea bed

Tied Back to the conductor or surface casing and does not carryany load

Prevents washouts of near surface unconsolidated formations

Ensures the stability of the ground upon which the rig is seated

Serves as a flow conduit for the drilling mud to the surface


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Casing


Casing Types

Conductor Pipe

Conductors can be driven, jetted in or drilled and cemented in place

Outermost casing string

Between 40-500ft in length onshore and up to 1000ftoffshore

Isolates weak formations

Prevents erosion of the ground below the rig

Provides a mud return path

Supports the weight of the subsequent casing stringsand the wellhead equipment


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Casing


Casing Types

Surface Casing

Depths vary from 300 to 5000ft

Setting depth is often determined by regulators orcompany policy rather than technical reasoning

Provides a base (means to nipple up) for the BOP

Provides a casing seat strong enough to safely shut-inthe well

Provides protection for shallow aquifers

Provides wellbore stabilisation


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Casing


Casing Types

Intermediate Casing

This casing type should be set within more competent formations than thesurface casing, thus allowing higher blow out protection for drilling deeper

Purely technical casing (a.k.a. protective casing)

Length varies from 7000 to 15000ft

Provides isolation of potentially troublesome zones

(abnormal pressures, unstable shales, lost circulationzones, salt sections, etc.)

Provides integrity to withstand the high mud weightsto reach TD or the next casing string


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Casing


Casing Types

Production Casing

This type of casing is often not cemented to surface

Set through the productive zone(s)

Designed to hold the maximum shut-in pressure

Designed to withstand the stimulating pressuresduring completions and workover operations

Provides zonal isolation (prevents fluid migration)

Confines production to wellbore

Provides the possibility to install subsurfacecompletion equipment

Provides protection in case of tubing failure


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Casing


Casing Types – Liners

Casing strings that don’t run all the way to the surface, beinghung in the previous casing shoe or even overlapping theprevious casing

Drilling Liner

Production Liner

Scab Liner

Scab Tie-Back Liner

Mainly run for economic reasons but also mechanical


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Casing


Casing Classification

API Standardisation is the most commonly used method of classifying casing

Outside Diameter (OD)

Inside Diameter (ID)

Length (range)

Weight

Type of Connection

Grade

API: 5C3, 5CT, 5L, 5B

Size


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Casing


Casing Size

(OD-ID)/2 = Wall Thickness

Manufacturers often produce casing slightlylarger than specified, nonetheless, there isan approved OD tolerance: -0.5% to +1%

ID is specified in terms of wall thickness anddrift diameter (size of a drift mandrel)

Minimum wall thickness is 87.5% of thenominal wall thickness


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Casing


Casing Length – Range

API 5CT

Casing Weight

Determined by nominal pipe body wall thickness expressed as weight per unit length

Nominal Weight, Plain-end Weight or Threaded and Coupled Weight (Average)

Tolerance: -12.5% to 0%

Range Length (ft) Average Length (ft)

1 16-25 22

2 25-34 31

3 Over 34 42


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Casing


Type of Connection

Mechanical device used to join pipe together (>90% of string failures occur in the connection)

Should be as strong as the pipe it connects and have similar geometry

Structural elements (properties)

Threads

Shoulders

Seal

Body


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Casing


Grade

The steel grade of the casing relates to the tensile strength of the steel

The steel grade is expressed as a code number which consist of a letter and a number

Letter Arbitrarily selected to provide a unique designation for each grade of casing

Number Designates the minimal yield strength of the steel (in thousand psi)

Example: K-55 Yield Strength of 55000psi


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Casing


Mechanical Properties

Casing is subjected to different loads during running, landing, cementing, drilling andproduction operations

Tensile LoadsBurstCollapseWear (erosion)

VibrationShock (pounding)Gun perforatingCorrosion


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Casing


Mechanical Properties


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Casing


How do we select it?

It usually depends on four considerations

1) Physical Strength (tension, burst, collapse, torsion, compression or combined tri-axial loads

2) Chemical Properties (resistance to H2S, CO2, water, etc…)

3) Availability

4) Cost


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Casing


How do we select it? – Physical Strength

Pressure – Burst

Pressure – Collapse

Axial – Tension

Maximum Load Case Condition for Burst

Calculate resulting loads (Load Line)

Multiply Load Line by Design factor (Design

Line)

Select Casing String with load capacity

equal or bigger than Design Line

Maximum Load Case Condition for Collapse



Line)

For casing selected in burst design, check that load capacity

equal or bigger then Design line

Maximum Load Case Condition for Tension



Line)

For casing selected in Collapse design, check

that load capacity equal or bigger then

Design line


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Casing


Casing Grade is selected! How long is each string and how many strings?

Casing Shoe/Seat Placement

Initial selection of casing setting depth is based on the pore and fracture pressure gradients forthe well

Lithological Column (problem zones, salt zones, fractured formations, etc…)

Minimum Hole Size in the reservoir

Temperature Profile

Fluids encountered (Water,oil, gas, H2S and CO2)

Well objectives (exploration – cost is secondary; or development – minimise cost)


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Casing


Casing Grade is selected! How long is each string and how many strings?

Casing Shoe/Seat Placement

Should Be designed from bottom upwards

After the preliminary shoe depth selection, hole sizes and mud weights has been done a study of kick tolerance should be carried out at each shoe

The hole section shouldn’t be drilled deeper than is possible to safely circulate out a kick!


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Casing


Casing Shoe/Seat Placement – Pore & Frac


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Drilling Fluids – Mud


Functions of Mud

Remove cuttings from the well

Control formation pressure

Suspend and release cuttings

Seal permeable formations (mud cake)

Maintain wellbore stability

Minimise reservoir damage

Cool, lubricate and support the bit and drilling assembly

Transmit hydraulic energy to the tools and bit

Ensure adequate formation evaluation

Control corrosion

Facilitate cementing and completion

Minimize impact on environment

Prevent gas hydrate formation


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Functions of Mud – Remove cuttings from the well

Function of

Mud Loggers determine the depth where the cuttings originated and analyse at their properties at the well site

Mud properties are critical are the primary cause of non productive time in drilling

operations

Strongly influence bit performance

Cutting size, shape and density

ROP

RPM

Flow rate and profile (annular velocity)

Wellbore orientation (inclination)

Mud Properties (density and viscosity)


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Functions of Mud – Control Formation Pressure

Avoid losses, kicks and formation instability


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Functions of Mud – Formation Damage (Skin)

The drilling muds selected in the drilling program need to minimise the formation damage,especially in the reservoir

Formation damage

Specially designed fluids are used for workover and completions

Reduction of the natural

porosity/permeability/

Wettability

Mud or drilling solids invade the formation matrix

Swelling of formation clays within the reservoir

Solids precipitation with the fluid mix (insoluble salts)

Mud filtrate and formation fluid form an emulsion


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Types of Mud

Water Based Mud

Water base with clays (bentonite) and other chemicalsLowest Cost but can react with some formations

Oil Based Mud

Base petroleum product (e.g. diesel); ToxicVery good drilling/formation propertiesMid Cost; use might be restricted

Synthetic Based Mud

Base synthetic oil (less toxic)Very good drilling/formation propertiesHighest cost

Thin and free flowing while pumped

Thick when pumping stops (gelling)

Non damaging to the reservoir (low reactivity)


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Mud Additives

Alkalinity and PH Control

Bactericides

Calcium Reducers

Corrosion inhibitors

Defoamers

Emulsifiers

Filtrate reducers

Flocculants

Lime, caustic soda and bicarbonate of soda

Paraformaldehyde caustic soda, lime and starch preservatives

Caustic soda, soda ash, bicarbonate of soda, some polyphosphates. Prevent contamination effects

Hydrated lime and amine salts. Prevent effects of oxygen and hydrogen sulphide (OBMs excellent anti-corrosion)

Reduce surface tension. Reduce foaming action in salt/saltwater mud based systems

Create an homogeneous mixture of two liquids. Fatty acids, amine derivatives and modified lignosulfonates

Reduce the amount of water lost to the formations. Bentonite clays, CMC and pre-gelatinized starch

Salt, hydrated lime, gypsum and sodium tetraphosphates


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Mud Additives

Foaming Agents

Lost Circulation Materials

Lubricants

Pipe-Freeing Agents

Shale-Control Inhibitors

Surfactants

Weighting agents

Used in air drilling. Create foam in the presence of water

Plug large openings preventing loss of whole drilling fluid. Nut shells (nut plug) and mica flakes

Used to reduce torque at the bit by reducing friction. Soaps, and some oils

Spotting fluids in areas of stuck pipe, reduce friction increase lubricity and inhibit formation hydration. Soaps, detergents, oils, surfactants

Control hydration, caving and disintegration of shale/clay formations. Gypsum, sodium silicate and calcium lignosulfonates

Reduce the interfacial tension between fluids (oil/water, water/solids, water/air, etc..)

Provide weight to the mud beyond its specific gravity. Barite, hematite, calcium carbonate and galena

4.drilling equipment firstpart

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