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Average Specific Weight of Formation - Hydraulic Fracturing Formula

γformation=(1ϕ)γmin+ϕγliq\gamma_{formation}=(1-\phi)\gamma_{min}+\phi\gamma_{liq}

Average Specific Weight of Formation - Hydraulic Fracturing calculates average specific weight of formation for hydraulic fracturing workflows in production engineering.

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How engineers use this formula

Use this formula when the listed inputs (gamma_min, gamma_liq, phi) are known and the assumptions behind the cited hydraulic fracturing 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, gamma_formation equals 2.32 p/cm^3.

gamma_minp/cm^3

2.65

gamma_liqp/cm^3

1

phifraction

0.2

Inputs

gamma_min

p/cm^3

Specific Weight of Minerals

gamma_liq

p/cm^3

Specific Weight of Liquid Phase

phi

fraction

Porosity

Outputs

gamma_formation

p/cm^3

Average Specific Weight of Formation

gamma_min

p/cm^3

Specific Weight of Minerals

gamma_liq

p/cm^3

Specific Weight of Liquid Phase

phi

fraction

Porosity

Source and review

reviewed

Saydam, T. 1967. Principles of Hydraulic Fracturing. ARI Publishing Co., Page 5.

Source

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