Rheology of Drilling and Completion Fluids

1
Lesson 2

• Rheology of Drilling and Completion Fluids

2
Rheology of Drilling and Completion Fluids

• Functions of Drilling/Completion Fluids
• Fluid Types,
• Fluid Models
• Introduction to Rotary Viscometer
• Other Testing Equipment
• Objectives of Monitoring Fluids

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Rheology of Drilling and Completion Fluids

• Read MI Chapters 1, 2, 3, 5
• Watch Multimedia program 3 4

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Functions of Drilling/Completion Fluids

• Remove cuttings from the well.
• Control formation pressures.
• Suspend and release cuttings.
• Seal permeable formations.

5
Functions of Drilling/Completion Fluids

• Maintain wellbore stability.
• Minimize reservoir damage.
• Cool, lubricate, and support the bit and drilling
  assembly.
• Transmit hydraulic energy to tools and bit.

6
Functions of Drilling/Completion Fluids

• Ensure adequate formation evaluation.
• Control corrosion.
• Facilitate cementing and completion.
• Minimize impact on the environment

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Fluid Types,

• Water based
• Oil based
• Air
• Mists
• Foams

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Flow Regimes

• Plug Flow
• Flat flow profile
• Velocity at walls is almost the same as in the
  middle
• Low velocities, and high viscosities

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Flow Regimes

• Laminar flow
• Parallel layers of mud flow
• Bullet shaped flow profile
• Velocity at the wall is approximately 0
• Velocity at the middle is maximum

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Flow Regimes

• Laminar Flow
• Drillstring
• Annulus

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Flow Regimes

• Turbulent flow
• Flow pattern is eratic

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Flow Regimes
Wellbore Turbulent flow Transition flow Complete
Streamline Incomplete Streamline Plug flow No
Flow

• Summary

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Fluid Models

• Newtonian Model
• Bingham Plastic Model
• Power Law Model

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Rheology

• The study of how matter deforms and flows.
• Primarily concerned with the relationship of
  shear stress and shear rate and the impact these
  have on flow characteristics inside tubulars and
  annular spaces.

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Hydraulics

• Describes how fluid flow creates and uses
  pressures.

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Rheological Models

• In drilling fluids, the flow behavior of the
  fluid must be described using rheological models
  and equations before hydraulic equations can be
  applied.

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Viscosity????

• Funnel Viscosity Marsh Funnel
• Apparent Viscosity
• Effective Viscosity
• Plastic Viscosity
• Yield Point
• Low-shear viscosity and Low-shear-rate viscosity
• Gel Strengths

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Funnel Viscosity
Measured in Sec/quart
Marsh Funnel
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Shear Stress Shear Rate

• Shear Stress Force required to sustain the
  shear rate.
• Shear Rate Function of the fluid velocity

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Newtonian Model

• Shear Stress, t, is proportional to the Shear
  Rate, g
• Plot intersects at the origin
• t mg
• m Viscosity, centipoise f300 reading

m
t
300 rpm
g
21
Bingham Plastic Model

• Shear Stress, t, is proportional to the Shear
  Rate, g
• Plot intersects at the Yield Point (not 0)
• t mpg ty
• mp PV
• ty YP

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Power Law Model

• Shear Stress, t, is proportional to the Shear
  Rate, g
• Plot intersects at the origin

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Which is correct?
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Introduction to Rotary Viscometer

• Viscosity, PV, YP, n, K all calculated from
  viscometer readings

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Viscometer
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Rotational Viscometer
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Other Testing Equipment

• Filter Press
• Measures filter cake thickness and Fluid Loss

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Other Testing Equipment

• pH meters used to measure pH of whole mud,
  filtrate, and filter cake
• Retorts used to determine oil content, etc.
• Test for sand content
• Test for clay content

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Objectives of Monitoring Fluids

• Identify potential hole problems and to identify
  their causes
• could be poor hole cleaning
• hole erosion
• formation damage
• sensitive formations
• pressure control problems