Methods and apparatus for improved acoustic data acquisition

摘要

A technique is designed to facilitate obtaining of acoustic data. The technique comprises traversing a tool through a subterranean formation from a first depth to subsequent depths. The tool receives a seismic signal during predetermined time windows. The seismic signal is generated by a seismic source which is activated at varying times relative to the predetermined time windows based on the depth of the tool.

主权项

1. A method of obtaining acoustic data, comprising:
traversing a tool through a subterranean formation on a drill string to a first depth during a drilling operation; stopping drilling for a first length of time at the first depth; activating an acoustic source at or near a surface location at a specific first instant in time relative to a beginning of the first length of time; recording a signal, produced via the source, with the tool during a predetermined recording period occurring during the first length of time; traversing the tool to a second depth deeper than the first depth during the drilling operation; stopping drilling for a second length of time at the second depth; activating an acoustic source at or near the surface location at a specific second instant in time relative to a beginning of the second length of time; and recording a signal, produced via the source, with the tool during a predetermined recording period occurring during the second length of time, the specific second instant in time being relatively earlier with respect to the beginning of the second length of time compared to the first instant in time with respect to the beginning of the first length of time; wherein a consistent downhole recording scheme is used such that the signals are received at a same desired time in the corresponding recording periods of the first length of time and the second length of time; and wherein the predetermined recording periods occur at a same predetermined time within the corresponding first length of time and the second length of time.