| 摘要 |
<p>A bottom hole assembly is configured with a drill bit section connected to a pulse generation section. The pulse generation section includes a relatively long external housing, the particular housing length being selected for the particular drilling location. The long external housing is positioned. closely adjacent to the borehole sidewalls to thereby create a high speed flow course between the external walls of the housing and the borehole sidewalls. The long external housing includes a valve cartridge assembly and optionally a shock sub decoupler. While in operation, the valve cartridge assembly continuously cycles and uses downhole pressure to thereby generate seismic signal pulses that propagate to geophones or other similar sensors on the surface. The amount of bypass allowed through the valve assembly is selectable in combination with the long external housing length and width to achieve the desired pulse characteristics.</p> |
