Enter the hydrostatic pressure contribution from the mud column in the annulus (psi), the hydrostatic pressure contribution from the influx column (psi), and the shut-in casing pressure (psi) into the Formation Pressure Calculator. The calculator will evaluate the Formation Pressure at the depth of interest. (If there is no influx in the annulus, the influx hydrostatic contribution is 0.) 

Formation Pressure Calculator

Enter any 3 values to calculate the missing variable

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