Dynamic testing of formation pressure bearing capacity before cementation

Abstract:

It is very important to the cementation design and safety to obtain the actual pressure bearing capacity of formation before cementing. The conventional formation integrity test(FIT) can not meet the cementing requirements due to limits of the formation fracture pressure at the upper casing shoe or the upper casing resistance to internal pressure. An innovative dynamic testing method was proposed in this paper to eliminate this issue and used in the field. This method operates as: increase flowrates at different levels after casing RIH and circulation, record the corresponding pump pressures, drilling fluid properties and amounts of leakage; then use rheology to calculate the formation bearing capacity at critical depths. Study indicates that the dynamic pressure testing method is effective for low pressure leaking wells, and very practical, meeting the FIT requirements for well cementation. The formation pressure testing results provide the basis and guarantee for the cementing design and safety.

Key words:cementing; dynamic test; pressure bearing capacity of strata; rheology