This invention relates to determining when drilling has been stopped during a drilling operation. More specifically, the invention relates to measuring noise downhole to determine when the mud pumps have been turned off.
Drilling for oil and other deposits within the Earth involves the drilling of wellbores into the Earth. To create the wellbore, a downhole drilling tool is suspended from a drilling rig and advanced into the earth via a drill string. During the drilling operation, it is desirable know the position and orientation of the bottom hole assembly and the drill bit. Typically, these measurements are made during brief pauses of the drilling operations. Such a pause may be for the purpose of adding a section of drill pipe to the drill string or for making a measurement or taking a sample of the formation and the fluids it contains. In some cases, a pause in drilling operations serves more than one purpose.
During such a pause, the drill bit is not being rotated and the mud pumps are often shut down. This is often the best time to make measurements related to the direction and inclination of the drill bit, called “taking a stationary survey.”