Acoustic methods and devices for determining the value of formation overpressure during drilling and for detecting gas packs containing hydrogen sulfide gas
A method for determining formation pressure during exploratory drilling for oil includes generating a series of negative pressure shock waves at successively increasing well pressures to characterize gas kick forming at the bottom of a well. Once the lower end of the gas kick has been formed, the well pressure level as detected by a pressure sensor near the surface of the well is used to calculate the formation pressure along with the weight of the fluid column located in the well.