Select the pressure to solve for and enter the other three values for a static shut-in annular pressure balance. Use gauge pressures with the same reference. This educational estimate does not replace trained well-control assessment.

undefined

Static shut-in annular pressure balance. Use gauge pressures with the same reference. Educational estimate; not a well-control procedure.

Formation Pressure Formula

The following formula is used to calculate the Formation Pressure. Here, HSPM and HSPI are hydrostatic pressure contributions from the mud segment and influx segment of the annular fluid column, respectively (so the total annular hydrostatic contribution is HSPM + HSPI). 

FP = HSPM + HSPI + SICP

Variables:

  • FP is the Formation Pressure (psi)
  • HSPM is the hydrostatic pressure contribution from the mud column in the annulus (psi) 
  • HSPI is the hydrostatic pressure contribution from the influx column in the annulus (psi) 
  • SICP is the shut-in casing pressure (psi) 

How to Calculate Formation Pressure?

The following steps outline how to calculate the Formation Pressure.

  1. First, determine the hydrostatic pressure contribution from the mud column in the annulus (psi).
  2. Next, determine the hydrostatic pressure contribution from the influx column in the annulus (psi). 
  3. Next, determine the shut-in casing pressure (psi). 
  4. Next, gather the formula from above = FP = HSPM + HSPI + SICP.
  5. Finally, calculate the Formation Pressure.
  6. After inserting the variables and calculating the result, check your answer with the calculator above. 

Example Problem:

Use the following variables as an example problem to test your knowledge.

hydrostatic pressure contribution from the mud column in the annulus (psi) = 100

hydrostatic pressure contribution from the influx column in the annulus (psi) = 230

shut-in casing pressure (psi) = 10

FP = HSPM + HSPI + SICP = 100 + 230 + 10 = 340 psi