Oil and Gas Engineering Concepts Quiz
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Questions and Answers

What is the minimum yield strength of API grade C90?

  • 80,000 psi
  • 90,000 psi (correct)
  • 95,000 psi
  • 100,000 psi

    • How does increasing temperature affect the mechanical properties of steel?

  • Decreases ductility and toughness
  • Increases yield strength and tensile strength
  • Decreases stiffiness and increases ductility (correct)
  • Increases toughness and yield strength

    • What must be done if gases like H2S and CO2 are present in the environment?

  • Increase temperature during production
  • Use standard steel alloys
  • Conduct tensile strength tests
  • Use special alloys such as Cr3+-doped (correct)

    • Which API casing grade has the highest minimum tensile strength?

    <p>Q125</p> Signup and view all the answers

    Why is casing design particularly critical in certain situations?

    <p>Failures can have catastrophic consequences for humans and the environment.</p> Signup and view all the answers

    What is a key advantage of PDC bits over roller cone bits?

    <p>PDC bits operate without roller bearings.</p> Signup and view all the answers

    Which type of bit is particularly resistant to abrasion and erosion?

    <p>Matrix bits</p> Signup and view all the answers

    What is a disadvantage of steel-PDC bits?

    <p>They require hardfacing for protection.</p> Signup and view all the answers

    For very soft formations with unconfined compressive strength less than 4,000 psi, which bit type is suitable?

    <p>PDC</p> Signup and view all the answers

    What is a characteristic of impregnated diamond bits?

    <p>They have a matrix body for added strength.</p> Signup and view all the answers

    What is true regarding the strength of formations and the type of bits suitable?

    <p>Medium formations can use PDC and Diamond bits.</p> Signup and view all the answers

    In what situation is a matrix bit preferred?

    <p>When a bit is likely to fail due to its body.</p> Signup and view all the answers

    What does the structural design of PDC bits allow regarding rock failure?

    <p>It enhances shear failure of rock.</p> Signup and view all the answers

    What is the primary purpose of the surface casing in a well?

    <p>Isolation of ground water and pressure control</p> Signup and view all the answers

    Which type of casing is primarily used for borehole stability and isolating low pressured or producing zones?

    <p>Intermediate Casing</p> Signup and view all the answers

    What does the production casing aim to achieve in a drilling operation?

    <p>Isolate the producing zone and protect against tubing leaks</p> Signup and view all the answers

    What is a notable characteristic of tiebacks in well construction?

    <p>Converts liners into full strings for wellhead</p> Signup and view all the answers

    Which casing type is important for structural support during the initial phase of drilling?

    <p>Foundation Pile</p> Signup and view all the answers

    What is one of the main utilities of casing in well construction?

    <p>To control formation pressures during production</p> Signup and view all the answers

    What is the purpose of drilling liners in a well?

    <p>To ensure borehole stability and local isolation</p> Signup and view all the answers

    What is the main purpose of using conductors in a drilling operation?

    <p>To provide structural support and protect against shallow gas</p> Signup and view all the answers

    What is the primary purpose of a near bit inclinometer in a drilling system?

    <p>To enable quick response to inclination changes</p> Signup and view all the answers

    Which of the following statements is true regarding slide drilling?

    <p>It can lead to micro-doglegs in the drilled hole.</p> Signup and view all the answers

    What are dual azimuthal gamma ray sensors used for in directional drilling?

    <p>To provide high and low side measurements in different azimuths</p> Signup and view all the answers

    What is a significant advantage of integrated slide drilling controls in comparison to traditional methods?

    <p>Ability to outperform competing systems</p> Signup and view all the answers

    What is the effect of the bent housing in slide drilling?

    <p>It enables changes to inclination and azimuth.</p> Signup and view all the answers

    Which challenge is associated with slide drilling compared to rotary drilling?

    <p>Risk of differential sticking</p> Signup and view all the answers

    What is the maximum build rate achievable using a steerable motor system?

    <p>$15°/100 ft$</p> Signup and view all the answers

    What is a disadvantage of rotating during drilling with a bent housing?

    <p>Averaging out the directional effect of the bent housing</p> Signup and view all the answers

    What is the primary function of the drill string?

    <p>Transmit rotary power and provide weight-on-bit</p> Signup and view all the answers

    Which method allows for monitoring while drilling?

    <p>Mud pulse telemetry</p> Signup and view all the answers

    What technology is expected to improve monitoring in near-future drilling?

    <p>Wired intelligent drillpipe</p> Signup and view all the answers

    Which component is NOT involved in the movement of the drill string?

    <p>Drill bit thread</p> Signup and view all the answers

    What is the primary function of the stator in a motor?

    <p>To create torque on the rotor</p> Signup and view all the answers

    How does a rotary steerable system (RSS) primarily steer the bit's orientation?

    <p>Through push-the-bit or point-the-bit technologies</p> Signup and view all the answers

    What determines the number of lobes on the stator compared to the rotor?

    <p>The rotor always has one less lobe than the stator</p> Signup and view all the answers

    What factor is NOT considered when determining bit economics?

    <p>Type of drilling fluid</p> Signup and view all the answers

    What is one of the key advantages of using a top drive compared to a rotary table?

    <p>Top drive rotates the drill string directly</p> Signup and view all the answers

    What is the typical bend angle range for a bent sub motor housing?

    <p>1 to 3 degrees</p> Signup and view all the answers

    What effect does drilling fluid have on a mud motor?

    <p>It is forced through the mud motor to rotate the bit</p> Signup and view all the answers

    If a motor is 30 feet long and has a 1.5-degree bent sub, what is the maximum build rate?

    <p>5 degrees</p> Signup and view all the answers

    What role does the polished stainless steel rotor play in the motor?

    <p>It allows mud flow to push the motor</p> Signup and view all the answers

    How does moving the bend closer to the bit affect the build rate?

    <p>It increases the theoretical build rate</p> Signup and view all the answers

    Which component is used to measure downhole orientation in steerable motors?

    <p>MWD-unit sensor</p> Signup and view all the answers

    What effect does the eccentricity of the rotor and stator have during operation?

    <p>It contributes to the torque generation on the rotor</p> Signup and view all the answers

    Study Notes

    Final Exam Material

    • Key points for the final exam include increasing pressure bursts and listening to and understanding audio information.
    • Additional topics cover bit types, drilling action, and formation strength.
    • Roller-cone/rock bits have milled teeth or tungsten carbide inserts (TCI).
    • Milled tooth bits have cutting structures made of milled steel.
    • TCI bits have cutting structures made of hard inserts pressed into a cone.
    • These bits are suitable for various formation types and applications.
    • The shape of the teeth on the cutting structure affects drilling action.
    • Larger teeth result in more aggressive cutting structures for softer formations.

    Bit Types: Roller-Cone / Rock Bits

    • Two types exist: milled tooth or tungsten carbide insert (TCI)
    • Milled tooth bits - cutting structure milled from steel
    • TCI bits - cutting structure made of hard inserts pressed into a cone
    • Suitable for many formation types and applications
    • Cutting action causes rock crushing and scraping
    • Teeth shape affects drilling
    • Larger teeth mean more aggressive cutting, used in softer formations

    Formation Strength & Bit Properties

    • Formation strength is linked to insert/tooth spacing and properties.
    • Soft formations use wide spacing with long, sharp inserts/teeth; high ROP and high cleaning flow rate.
    • Medium formations have relatively wide spacing with shorter & stubbier inserts/teeth; relatively high ROP and relatively high cleaning flow rate.
    • Hard formations use close spacing with short, rounded inserts/teeth; relatively low ROP and relatively low cleaning flow rate.

    Fixed Cutter/Drag Bit - PDC

    • PDC bits have no moving parts, a key advantage over roller-cone bits
    • Rock failure is by shear rather than crushing in PDC bits, requiring less energy
    • Steel-PDC bits are made of high-performance alloy steel
    • Structurally stronger than matrix bits
    • Easier to manufacture
    • Dimensionally more accurate and repeatable
    • Matrix bits are cast from tungsten carbide grains with a metallic binder.
    • More resistant to abrasion and erosion than steel bits
    • Preferred for smaller diameter holes where the body of the bit is likely to cause failure

    Fixed Cutter Bit - Impreg & Diamond Bits

    • Matrix PDC body (made from materials like tungsten carbide)
    • Matrix is impregnated with embedded diamonds to prevent breakage
    • Diamonds are small, leading to smaller depth of cuts
    • Used with turbodrills or high-speed PDMs
    • Sensitive to shocks and vibrations

    Bit Selection

    • Bit selection is based on formation description and unconfined compressive strength
    • Suitable bit types are chosen based on formation hardness
    • Bit selection considers economic factors, time savings, rig costs, and bit prices (next slide)
    • The criteria also includes directional requirements and that the operating envelope for PDC's continues to expand

    Drill String - DS

    • The drill string (DS) transmits rotary power (torque) to the bit, provides weight-on-bit (WOB), and controls well trajectory, transporting drilling fluid to the bit.
    • Monitoring and logging while drilling (MWD/LWD) are enabled through mud pulse telemetry
    • Future monitoring will be done with wired/intelligent drillpipe

    Drill String Components

    • The drill string includes various components like the Kelly, Rotary Table, Top Drive, Mud Motor, Drill Collars, Stabilizers, and Bottom-Hole Assembly (BHA).

    Drill Pipe

    • Lengths range from 18-22 ft (now obsolete), 27-30 ft, and 38-45 ft
    • Common sizes are: 3 ½", 4 ½", 5", in addition to others
    • Larger drill pipe is selected for larger diameter hole sizes, lower frictional losses, and increased torsional strength
    • API standards classify and indicate grades and strengths.

    Drill Collars

    • Large diameter, thick and heavy-duty tubes
    • Connected by threading similar to the drill pipe
    • Provide weight at the bottom of the well and are designed for compressive loads.
    • It is common to avoid exceeding 80% of the buoyed drill collar weight.

    Heavy-Wall Drill Pipe (HWDP)

    • Lies in between drill collars and regular drill pipe in terms of weight
    • Special tubes with wear pads in the middle (central wear pad) and long tool joints
    • More resilient to fatigue and compression
    • Used in slim-hole and high deviation drilling applications, due to less friction and reduced differential sticking risk

    Stabilizers

    • Centralize the drill string in the hole
    • The location of stabilizers along the string, their size, and hole size all impact their effectiveness
    • They act as a fulcrum in directional drilling operations

    Miscellaneous String Components

    • Subs, floats subs, circulators, bent subs, and more are included here as necessary components.

    Rotary Steerable Systems (RSS)

    • Steers by applying side load at the bit
    • Active cutting structuring and gauge used to cut sideways into the formation
    • The design uses short gauge bits as an advantage for quick responses.
    • Active/responsive steering is a benefit but can lead to hole spiraling
    • Alternatively, Point-the-bit steers by pointing or tilting the bit in the preferred wellpath without need for side loading
    • Longer gauge bits are used to prevent hole spiraling

    Downhole Motors (PDMs)

    • Positive displacement motors (PDM's) consist of various components: Dump or Bypass valve, Power Assembly (rotor - stator), Connecting Rod / Universal Joint, Bearing in Drive Shaft / Sub, and Bit Sub.
    • Types of PDMs include Mono Lobe and Multi Lobe types

    Well Path Design

    • Special case one and two discuss well path design in vertical and horizontal situations
    • Formulas are used to calculate axial, horizontal, and vertical changes

    Typical 2-D Well Profiles

    • Three major types are shown: Type 1 is a vertical well, Type 2 is a well with a build section, and Type 3 is a continuous build well, used for directional drilling

    Unconventional Wells / Casing Schemes

    • Surface + production, with multiple surface casing options, depending on the specifics of the formation
    • Multiple surface casing possible, often in normally pressured formations
    • In geo-pressured formations, intermediate casings are also part of the design

    Casing Design / Barrier Design

    • Different types include conventional, secondary barriers, and cemented completion casing

    API Casing Grades

    • Standardized casing grades with minimum yield strengths, maximum yield strengths, and minimum tensile strengths provided

    Effect of Environment

    • Temperatures have a significant impact on mechanical properties in casing
    • Yield strength decreases while toughness increases with higher temperature.
    • Presence of gases like CO2 and H2S reduces steel's toughness

    Casing Design Considerations

    • Human lives and the environment are critical factors for consideration during design
    • The system's behavior under different loads must be modeled and controlled considering Mechanical equipment properties
    • Operational limits and safety margins need to be set and communicated

    Design Philosophy/ Working Stress

    • Explains the concept of maximum load and minimum resistance, with built-in safety factors when considering working stress

    Loads and Force on Casing

    • Loads acting upon the casing/strings during periods such as drilling, completions, stimulation, workovers, production, abandonments, and decommissions

    Casing Failure Example

    • Various load cases exist including uniaxial tension, compression, burst, collapse (with and without internal pressure), and biaxial collapse

    Types of Casing Failures: Burst

    • Pipe burst occurs when the internal pressure (P₁) exceeds external pressures (P₂) such that the pipe exceeds its API yield stress
    • Pressure testing and shut-in operations need careful consideration and documentation

    Casing Point Selection

    • Regulatory issues like shallow aquifers and production zone coverage need consideration
    • Geologic considerations, like unusual formations, pore pressures, and unstable ground conditions, impact casing point
    • Pressure tolerance, for handling kicks, also guides casing point selection

    "Top-Down" Casing Point Selection

    • Hydrostatic pressure needs to be greater than pore pressure to prevent influx and less than “formation strength” to avoid fractures
    • Maintaining margin on limiting values, for safety, is discussed

    Well Path Design – Special Cases

    • Special case one and two provide formulas calculating axial, horizontal, and vertical changes and considering constant azimuth and 90° deviation respectively

    Typical 2-D Well Profiles

    • Type 1, 2, and 3 provide graphical representation for vertical, build/hold, and continuous build directional drilling schemes

    Cementing Optimization

    • Four possible means of optimizing cementing, with respect to displacement efficiency, are mud conditioning, pipe rotation, standoff, and turbulent flow
    • Mud conditioning, pipe rotation, standoff, and turbulent flow techniques are used in different ways, depending on the need

    Cement Composition

    • The mineral makeup and composition of cement are noted

    Cement Grades and Chemistry

    • Categorizes cement grades based on ASTM standards in terms of contents of C3S, C2S, C3A, C4AF, and fineness(cm2/g)
    • Describes methods of obtaining particular properties, such as high early strength, better retardation, low heat of hydration, and resistance to sulfate attack

    Other Reasons for Cementing

    • Well tubular support
    • Preventing wellbore/tubular collapse, borehole instability, and mud losses
    • Corrosion protection and kick-off plugs
    • Well abandonment

    Cement Water Requirements

    • Water requirements by weight of cement for different API classes (A & B, C, D, E, F, H & G) are noted

    Schematic of Heat Evolution for Portland

    • Stages 1, 2, 3, 4, and 5 discuss pre-induction, dormant induction, acceleration, deceleration, and steady state, respectively.
    • Chemical action, including hydration and gel formation (exothermic), slow gel formation, grain hydration and water filling spaces (exothermic), setting phase and gel hydrate intergrowth, and hardening via further C3S hydration
    • Time scales are noted

    Cement Additives and Roles

    • Different additives, their use, chemicals, and benefits are listed

    Casing Centralization

    • Different percentages of casing centralization in relation to mud and cement are noted

    Wellpath Design: Special Cases

    • Provides equations and methods to design well paths considering both vertical and horizontal situations, 90° deviation and constant azimuth

    Typical 2-D Well Profiles

    • Describes and displays graphical representation of the major types of directional drilling schemes including vertical, build section, tangent section and drop off section and continuous build well

    Example 3/4 Solutions

    • Solutions to a couple of casing design examples are demonstrated, that is applicable to both "Top-Down" & "Bottom-Up" methods of design

    Design Process: Conventional Casing OD Selection

    • Explains the conventional design process graphically exhibiting relationships between casing selection and Bit and hole sizes.

    The Value of Cementing

    • Expounds on the importance of cementing during well operations
    • Discusses some of the reasons relating to completion, productivity, environment and cost over the entire life of the well.

    Casing/Liner Cementation

    • Illustrates the use of cementing during the placement of casing and liner pipes

    Cement Evaluation: Bond Logging

    • Describes the methods and concepts of bond logging to evaluate cement quality and its bonding to surround formations.

    Cementing Problems

    • Highlights some of the potential issues relating to cementation operations, including problems with casing centralization, and other similar scenarios

    Additional Topics

    • Further topics include slide steering processes both I and II, different types of directional drilling systems, and definitions of terms like dog leg severity (DLS), and others which may prove relevant to the specifics required for the final exam.

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    What is Important for the Final Exam PDF

    Description

    Test your knowledge on important concepts in oil and gas engineering, including casing grades, bit types, and mechanical properties of steel. This quiz covers key topics essential for professionals in the field and aims to enhance your understanding of drilling and casing design. Challenge yourself with questions about yield strength, temperature effects, and bit advantages.

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