Mud operated pulser

A transmitter assembly for a mud pulse telemetry MWD system, comprising;

• an outer housing;
• an orifice fixedly positioned within said housing;
• a poppet movably positioned within said housing to affect mud flow through said orifice, said poppet having a face with a surface area A.sub.1 ;
• and
• a piston assembly connected to said poppet for controlling the position of said poppet relative to said orifice, said piston assembly including a piston having a surface area A.sub.2 ;
• a by-pass conduit defining a mud flow path by-passing said orifice and through said piston assembly;
• a pilot valve for enabling and disabling mud flow through said by-pass conduit;
• wherein mud flow through said by-pass conduit creates a force on said piston which is greater than the force on said poppet, causing said poppet to shut with respect to said orifice.

A mud pulser for an MWD system, comprising;

• an orifice;
• a poppet movably positioned with respect to said orifice, said poppet having a face with a surface area A.sub.1 ;
• and
• a piston assembly connected to said poppet for controlling the position of said poppet relative to said orifice, said piston assembly including a piston having a surface area A.sub.2 ;
• a by-pass conduit defining a mud flow path by-passing said orifice and through said piston assembly;
• a pilot valve for enabling and disabling mud flow through said by-pass conduit;
• and
• a plurality of pressure relief valves in said by-pass conduit;
• wherein each of said pressure relief valves is set with a different relief pressure to enable said mud pulser to generate an acoustic signal with more than two amplitude levels.

A mud pulser for an MWD system, comprising;

• an orifice;
• a poppet movably positioned with respect to said orifice, said poppet having a face with a surface area A.sub.1 ;
• and
• a piston assembly connected to said poppet for controlling the position of said poppet relative to said orifice, said piston assembly including a piston having a surface area A.sub.2 ;
• a by-pass conduit defining a mud flow path by-passing said orifice and through said piston assembly;
• a pilot valve for enabling and disabling mud flow through said by-pass conduit;
• and
• a motor operated pressure relief valve in said by-pass conduit;
• wherein said motor operated pressure relief valve is capable of being set with a variety of different relief pressure values to enable said mud pulser to generate an acoustic signal with more than two amplitude levels.

A transmitter assembly for a mud pulse telemetry system, comprising:

• an outer housing;
• an orifice positioned within said housing;
• a poppet movably positioned within said housing with respect to said orifice to affect mud flow through said orifice;
• a piston assembly connected to said poppet for controlling the position of said popper relative to said orifice;
• a by-pass conduit defining a mud flow path by-passing said orifice, said by-pass conduit including a passage through said piston assembly;
• a pilot valve for enabling and disabling mud flow through said by-pass conduit;
• and
• a pressure control valve connected in said by-pass conduit for defining the maximum mud pressure generated by said transmitter assembly.