Downhole seismic source

Improved apparatus for generating downhole seismic signals comprising:

• an elongate hollow body arranged to be lowered into a well bore;
• a striker mass movably located in said body;
• an anvil movably located in said body relatively below said striker mass and engageable thereby, said anvil having a lower end exposed to fluid in the well bore when said body is lowered into the well bore;
• a high pressure gas chamber in said body defined by an upper surface on said striker mass and by said body, so that gas in said gas chamber propels said striker mass toward and into engagement with said anvil to generate said seismic signal;
• and
• shock means connected to the lower end of said anvil and projecting downwardly therefrom for enhancing the seismic signal;
• and
• control means in said body for releasing said striker mass to be propelled by gas in said gas chamber.

Improved apparatus for generating downhole seismic signals comprising:

• an elongate hollow body arranged to be lowered into a well bore;
• an actuator piston movably located in said body and having a lower end engaging, when lowered into the well bore, the medium into which said seismic signals are to be generated;
• a reaction mass located in said body for reducing vibration of said body, and having a cylinder formed therein for receiving said actuator piston;
• a reaction mass support member located in said body between said reaction mass and said body, said reaction mass support member being tuned to prevent movement of said reaction mass relative to said body;
• and
• control means in said body for activating said actuator piston to generate said seismic signals.

Improved apparatus for generating downhold seismic signals comprising:

• an elongate hollow body arranged to be lowered into a well bore;
• signal generating means in said body operably having a lower portion located so that, when said body is lowered into the well bore, said lower portion is in contact with a medium into which said seismic signals are to be transmitted;
• a support member connected to said lower portion;
• a plurality of wave generating shock members spaced along said support member;
• and
• control means in said body for activating said signal generating means to generate said seismic signals.

Improved apparatus for generating downhole seismic signals comprising:

• an elongate, hollow body arranged to be lowered into a well bore;
• a striker mass movably located in said body;
• an anvil movably located in said body relatively below said striker mass and engageable thereby, said anvil having an upper end and having a lower end exposed to fluid in the well bore;
• a high pressure gas chamber in said body defined by an upper surface on said striker mass and by said body, whereby said gas propels said striker mass toward and into engagement with said anvil to create said seismic signal;
• shock means connected the lower end of said anvil and projecting downwardly therefrom for enhancing the seismic signal;
• and,
• latch means in said body for releasably retaining said striker mass in a ready position out of engagement with said anvil.

Improved apparatus for generating downhole seismic signals comprising:

• an elongate, hollow body arranged to be lowered into a well bore;
• anchor means in said body for securing said bore at desired locations in a well bore, said anchor means including a plurality of resilient anchor shoes engageable with the well bore wall, and anchor drive means for moving said shoes into and out of holding engagement;
• a striker mass movably located in said body and having a retraction shoulder thereon;
• an anvil movably located in said body below said striker mass, said anvil having an upper end engageable thereby and having a lower end exposed to fluid in the well bore;
• a high pressure gas chamber in said body defined by an upper surface on said striker mass and by said body hereby said gas propels said striker mass toward and into engagement with said anvil to create said seismic signal;
• retraction means in said body for returning said striker mass to a ready position out of engagement with said anvil, said retraction means including a retraction rod movable with respect to said striker mass and having a flange on one end engageable with the retraction shoulder on said striker mass, and means for moving said retraction rod between a first position out of engagement with said retraction shoulder and a second position engaging said retraction shoulder for moving said striker mass to said ready position;
• shock means connected to the lower end of said anvil and projecting downwardly therefrom for enhancing said seismic signal, said shock means including a support member connected to said anvil and a plurality of shock members spaced along said support member;
• latch means in said body for releasably retaining said striker mass in said ready position out of engagement with said anvil;
• and
• a low pressure gas chamber in said body defined by a lower end of said striker mass, by said body, and by the upper end of said anvil.

Improved apparatus for generating downhold seismic signals comprising:

• an elongate, hollow body arranged to be lowered into a well bore;
• a reaction mass located in said body for reducing vibration of said body;
• an actuator piston movably located in said body and having a lower end which, when said body is lowered into the well bore, engages a medium into which said seismic signals are to be generated;
• a cylinder in said reaction mass for receiving said piston;
• and
• control means in said body for causing reciprocation of said actuator piston to set up vibrations in said medium.