Translations:Velocity analysis - book/5/en

Velocity estimation refers to finding empirical values for the velocity function. One method of measuring the velocity function v(z) is to conduct measurements in an existing oil well or borehole. An instrument consisting of a seismic pulse generator with two attached detectors separated by a fixed distance is lowered into the hole. This fixed distance is of the order of a few meters or less. As the instrument gradually is pulled back up the borehole, changes in the transit time across the fixed distance between the two detectors are recorded as a continuous curve. This curve is known as either a continuous velocity log (CVL) or a sonic log. The seismic wave velocity is the reciprocal of the interval transit time.