Drilling System Pressure Loss Calculations

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Lesson 6

• Drilling System - Pressure Loss Calculations

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Drilling System - Pressure Loss Calculations

• Read MI Chapter 5
• Multimedia Program 3 4

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Drilling System - Pressure Loss Calculations

• Hydrostatics
• Buoyancy
• Flow through pipes and annuli
• Flow path
• Pressure loss calculations

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Hydrostatics

• Liquid columns
• Gas columns
• Complex Columns

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Hydrostatics in Liquid Columns

• 1 cu.ft. of water
• 62.4 lb/cuft
• Area 12x12
• 144 sq.in
• 62.4 / 144 .433 psi/ft
• .433psi/ft/8.333 ppg
• 0.051962
• 0.052 psi/ft/ppg
• HSP 0.052 x MW x TVD

1ft x 1ft x 1ft
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Hydrostatics in Liquid Columns
All are full of 10.0 ppg mud
MD 12,000 TVD 10,000
MD 14,000 TVD 10,000
MD TVD 10,000
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Hydrostatics in Gas columns
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Hydrostatics in Complex Columns
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Hydrostatics in Complex Columns
0.052 x 10.5 x 7000 3822 psi 0.052 x 8.5 x 300
133 psi 0.052 x 12.7 x 1700 1123 psi 0.052
x 16.7 x 1000 868 psi Total 5946 psi
0.052 x 9 x 10,000 4680 psi 5946 - 4680
1266 psi
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Equivalent Density Concept

• EMW Pressure/ (0.052 x TVD)
• Equivalent mud weight is the total pressure
  imposed at a given depth expressed in ppg
  equivalent
• e.g. 5946/ (0.052 x 10000) 11.43 ppg

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Buoyancy

• The net effect of hydraulic pressure acting on a
  foreign material immersed in the well fluid.

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Buoyancy

• F1 p1A 0.052 x MW x D x A Downward force
• F2 p2A 0.052 x MW (D h)A Upward Force
• The resultant buoyant force
• Fbo F2 - F1 0.052 x MW x A (Dh-D)
• 0.052 x MW x A x h

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Buoyancy

• Fbo Weight of a the fluid displaced.
• The effective weight of the submerged object is
• We W - Fbo W1-(rm/rs)

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Flow through pipes and annuli
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Flow through pipes and annuli
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Flow path
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Pressure loss calculations
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Turbulence - Newtonian

• Onset of turbulence occurs at a Reynolds number
  of 2100
• Table 4.6 gives equations for Reynolds number

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Friction Factor - Newtonian
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Turbulence -Bingham Plastic
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Turbulence - Power Law
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Velocity Flow Behavior Parameters
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Turbulence Criteria
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Laminar Flow Frictional Pressure
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Turbulent Flow Frictional Pressure
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Example 4.21

• Given
• MW 9.0 ppg Newtonian fluid
• Viscosity 15 cp
• Depth 10,000
• Hole size 7
• DP size 5
• q 80 gpm
• Required
• Static and circulating BHP (assume Laminar)

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Solution

• Static BHP
• 0.052 x 9 x 10,000 4680 psig

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Solution

• Frictional pressure

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Solution

• Circulating BHP HSP Friction
• 4680 51 4731 psig.

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Turbulence?

• Critical Reynolds number 2100
• What is the critical velocity

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Critical Velocity?