What is a fit test in drilling?

A Formation Integrity Test (FIT) is a test of the strength and integrity of a new formation and it is the first step after drilling a casing shoe track. An accurate evaluation of a casing cement job and of the formation is extremely important during the drilling of a well and for subsequent work.

What does leak off test determine?

A leak-off test is one of the most common procedures to test the fracture pressure of the exposed formations. After cementing and drilling out of the casing shoe, the LOT is run to verify that the casing, cement, and formation can withstand the pressure needed to safely drill the next section of the well.

How do you calculate casing pressure?

The shut-in casing pressure (SICP) is a measure of the difference between the formation pressure and the HSP in the annulus when a kick occurs. The pressures encountered in the annulus can be estimated using the following mathematical equation: FP = HSPmud + HSPinflux + SICP.

What are leak off and Formation Integrity tests?

Leak Off Test and Formation Integrity Test(FIT), also termed the Limit Test, are for formation strength pressure tests made just below the casing seatprior to drilling ahead. These tests are carried out to: Investigate the cement seal around the casing shoe which should be at least as high as the predicted fracture pressure for the area.

What kind of test is leak off Test?

LOTs are also recommended to be carried out on both appraisal and development wells. Leak Off Test and Formation Integrity Test(FIT), also termed the Limit Test, are for formation strength pressure tests made just below the casing seatprior to drilling ahead.

When to use the formation integrity test ( fit )?

The Information resulting from Formation Integrity Tests (FIT) is used throughout the life of the well and also for nearby wells. Casing depths, well control options, formation fracture pressures, and limiting fluid weights may be based on this information.

Is the NPT required for the formation integrity test?

However, resistance to conducting FITs is typical because of the NPT required. In contrast, a LOT is comparable to testing a pressure vessel to leak, rupture, or become permanently deformed. The pressure is raised until the last casing shoe or formation is fractured as indicated by leak-off.