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Reservoir EngineeringWell Performance

Critical Rate for Horizontal Wells in Edge-Water Drive Reservoirs Formula

qo=(4.888×104)ΔρhkhkvLqcμoq_o = (4.888 \times 10^{-4}) \cdot \Delta\rho \cdot h \cdot \sqrt{k_h \cdot k_v} \cdot L \cdot \frac{q_c}{\mu_o}

Critical Rate for Horizontal Wells in Edge-Water Drive Reservoirs calculates critical oil rate for well performance workflows in reservoir engineering.

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How engineers use this formula

Use this formula when the listed inputs (e1, e2, e3, e4, Delta_rho, h, L, x_e, k_h, k_v, mu_o) are known and the assumptions behind the cited well performance relationship match the engineering case being checked.

Assumptions

  • Input values are representative for the well, reservoir, fluid, or equipment case being evaluated.
  • The declared units match the field-unit constants used in the formula.
  • The cited formula applies to the selected petroleum engineering workflow.

Limitations

  • The calculation does not replace a full engineering model or operating procedure.
  • Accuracy depends on the source correlation, assumptions, input quality, and unit consistency.

Common mistakes

  • Mixing unit systems without converting the inputs.
  • Using default example values as field recommendations.
  • Applying the formula outside the source assumptions.

Default example

Using the default inputs, q_o equals 8.015066 STB/day.

e1dimensionless

0.023

e2dimensionless

0.0013

e3dimensionless

0.022

e4dimensionless

0.0013

Delta_rhog/cc

0.2

hft

50

Lft

1000

x_eft

500

k_hmD

10

k_vmD

5

mu_ocP

1

Inputs

e1

dimensionless

Empirical Constant for c₁

e2

dimensionless

Empirical Constant for c₂

e3

dimensionless

Empirical Constant for c₃

e4

dimensionless

Empirical Constant for c₄

Delta_rho

g/cc

Density Difference Between Water and Oil

h

ft

Pay Zone Thickness

L

ft

Length of Horizontal Well

x_e

ft

Distance to Constant Pressure Boundary

k_h

mD

Horizontal Permeability

k_v

mD

Vertical Permeability

mu_o

cP

Oil Viscosity

Outputs

c_1

intermediatedimensionless

Dimensionless Constant c₁

c_2

intermediatedimensionless

Dimensionless Constant c₂

c_3

intermediatedimensionless

Dimensionless Constant c₃

c_4

intermediatedimensionless

Dimensionless Constant c₄

q_c

intermediatedimensionless

Critical Rate Component

q_o

STB/day

Critical Oil Rate

z_c

ft

Critical Coning Height

Source and review

reviewed

Ahmed, T., McKinney, P.D. Advanced Reservoir Engineering, Gulf Publishing House, Burlington, MA, 2015.

Source

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