Understand About Formation Pressure

Formation pressure is the pressure of fluid contained in pore space of rock and there are 3 categories of the formation pressure which are normal pressure, abnormal pressure and subnormal pressure.

1. Normal Pressure: Normal pressure is the hydrostatic of water column from the surface to the subsurface formation. The concentration of salt in water affects the normal pressure. Higher salt concentration in water, higher specific gravity of water will be. Therefore, the normal pressure can vary from slightly salt 0.433 psi/ft (8.33 PPG) to highly concentrated salt 0.478 psi/ft (9.2 PPG) based on salt concentration in water.

2. Abnormal Pressure: The abnormal pressure is the pressure greater than the pressure column of water. Generally, the abnormal pressure zones are good reservoir which oil companies are looking for. This kind of pressure can create well control problem.

3. Subnormal Pressure: The subnormal pressure is the pressure that is less than normal pressure and it  possibly causes lost circulation problems.

Looking at the drawing below, it demonstrates the comparison of formation pressure when drilling into each pressure regime. At the same True Vertical Depth (TVD), subnormal pressure shows least pressure in comparison to others. However, abnormal pressure gives the highest pressure at the same level of TVD.

3 normal abnormal subnormal pressure

Reference book: Well Control Books

Related Post

Slow Circulation Rate (SCR) Slow Circulation Rate is a circulation rate which will be used in well kill operation. Typically, slow circulation rate pressure (SCR) is recorded fro...
Boyle’s Gas Law and Its Application in Drilling Understand Boyle’s Gas Law Boyle’s law states that at constant temperature, the absolute pressure and the volume of a gas are inversely proportiona...
Well Control Formulas Part 2 These are some formulas used in well control operation. I will spit all content into several parts ^_^ Equivalent Circulating Density (ECD) , ppg ...
Post Shut-In Procedures While Tripping -What data ... After you complete shut in procedure while tripping, there is following information that must be recorded before making any decision on how to kill th...
Share the joy
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  •  

About DrillingFormulas.Com

Working in the oil field and loving to share knowledge.
Tagged . Bookmark the permalink.

2 Responses to Understand About Formation Pressure

  1. kresimer zubac says:

    is there any sheet or software good for pore pressure prediction while drilling?
    thanks.

Leave a Reply

Your email address will not be published. Required fields are marked *