| Formation Integrity Test (FIT) is the method to | | | | Pressure required for FIT = (14.5-9.2) x 0.052 x |
| test strength of formation and a casing shoe by | | | | 4000 = 1102 psi |
| increasing Bottom Hole Pressure (BHP) to | | | | Note: The acronyms are listed below;psi = pound |
| designed pressure. FIT is normally conducted to | | | | per square inchppg = pound per gallonft = feet |
| ensure that formation below the casing show will | | | | Formation Integrity Test (FIT) procedures are as |
| not be broken while drilling the next section with | | | | follows; |
| higher bottom hole pressure. Normally, drilling | | | | 1. Drill out new formation few feet, circulate |
| engineers in town will design how much formation | | | | bottom up and collect formation samples to |
| integrity test pressure required and a unit of FIT | | | | confirm that new formation is drilled to and then |
| is normally in pound per gallon unit. | | | | pull a drill string into the casing shoe. |
| How to Calculate Pressure Required for Formation | | | | 2. Close annular preventer or pipe rams, line up a |
| Integrity Test. | | | | cement pump, and circulate through an opened |
| Before forming formation integrity test, you | | | | choke line to ensure that surface line is fully filled |
| should know pressure required for Formation | | | | with drilling fluid. |
| Integrity Test. The formula showed below | | | | 3. Stop the pump and close a choke valve. |
| demonstrates you how to calculate required FIT | | | | 4. Gradually pump small amount of drilling fluid into |
| pressure. | | | | a well with constant pump strokes and |
| Pressure required for FIT (psi) = (Required FIT in | | | | recommended pump strokes are 5 to 10 strokes |
| ppg - Current Mud Weight in ppg) x 0.052 x True | | | | per minute. Record total pump strokes, drill pipe |
| Vertical Depth of shoe in feet | | | | pressure and casing pressure. Pump until casing |
| Example below demonstrates how to use the | | | | pressure reaches the pressure required for |
| formula to calculate pressure required for the | | | | formation integrity test. Stop pumping and hold |
| test: | | | | pressure for few minutes to confirm pressure |
| Required FIT (ppg) = 14.5 | | | | stability. |
| Current mud weight (ppg) = 9.2 | | | | 5. Bleed off pressure and open up the well. Then |
| True Vertical Depth of shoe (ft) = 4000 TVD | | | | start drilling operation. |