Torsional wave generator

A torsion wave generator for connection to a rotatable drill string, for propagating torsional waves along the string, said torsional wave generator comprising:

• a body, rigidly connected to the drill string, and capable of receiving and passing a flow of drilling mud supplied down the drill string;
• a reaction mass rotatably connected to said body;
• and
• torque producing means utilizing the flow of drilling mud to produce a torque between said body and said reaction mass, thereby producing a torsional wave in the drill string, regardless of the speed of rotation of the drill string.

Apparatus for producing torsional acoustic waves in a drill string in accordance with information signals derived from sensors in a borehole, said apparatus comprising:

• (a) a wave generator housing rigidly connected between sections of a drill string near the lower end thereof;
• (b) a reaction mass mounted for a limited degree of rotation with respect to said housing;
• (c) a plurality of fluid chambers rigidly connected to one of said elements (a) and (b);
• (d) a plurality of radial vanes rigidly connected to the other of said elements (a) and (b), and dimensioned to provide an essentially fluid-tight seal between said vanes and said chambers;
• (e) a mud directing valve disposed in said housing and having a fluid input path for receiving a flow of drilling mud down the drill string, and three alternate fluid output paths;
• (f) first, second and third sets of mud ducts coupled to said mud directing valve to receive mud along said three alternate fluid output paths, respectively, said first set of mud ducts communicating directly with the drill string below said housing, and said second and third sets of mud ducts communicating with said chambers on opposite sides of said vanes;
• (g) means for controlling said mud directing valve to direct mud into one of said first, second and third sets of mud ducts, in accordance with information signals to be transmitted as acoustic waves;
• (h) an exhaust port in each of said chambers, said ports being uncovered upon sufficient movement of said vanes, and said ports communicating with the drill string to provide a continuous path for the mud;
• and
• (i) means for biasing said vanes into a central position with respect to said chambers, to ready said apparatus for generation of another torsional wave when the mud is flowing through said first set of mud ducts;
• whereby flow of mud into said chambers produces a torque between said reaction mass and said generator body, and produces relative motion between said reaction mass and the drill string, resulting in the propagation of a torsional wave in the drill string.

A method for generating torsional acoustic waves in a drill string, for the transmission of telemetry data, said method comprising the steps of:

• generating a torque between a reaction mass mounted for limited rotation about a drill string and a generator housing rigidly connected into the drill string;
• rotating said generator housing and the drill string with respect to said reaction mass, as a result of the generated torque;
• and
• thereby propagating a torsional wave along the drill string, independently of the drill string angular velocity.

A torsional wave generator capable of propagating torsional waves along a drill string for the purpose of transmitting information signals, said torsional wave generator comprising:

• reaction mass means rotatably coupled to the drill string;
• and
• means effective independently of drill-string angular velocity, for producing a torque between said reaction mass means and the drill string, whereby a torsional wave is generated for propagation along the drill string;
• and wherein said means for producing a torque includes
• first fluid coupling means rigidly connected to the drill string and having a plurality of vanes,
• second fluid coupling means rigidly connected to said reaction mass means and having a like plurality of chambers into which said vanes extend, and
• valve means for selectively controlling the flow of drilling mud to produce a relative torque between said first and second fluid coupling means, said valve means being operative to direct drilling mud into said chambers to effect relative motion in a selected direction between said vanes and said chambers.

A torsion wave generator for connection to a rotatable drill string, for propagating torsional waves along the string, said torsional wave generator comprising:

• a body, rigidly connected to the drill string, and capable of receiving and passing a flow of drilling mud supplied down the drill string;
• a reaction mass rotatably connected to said body;
• and
• torque producing means utilizing the flow of drilling mud to produce a torque between said body and said reaction mass, thereby producing a torsional wave in the drill string, regardless of the speed of rotation of the drill string;
• and wherein said torque producing means includes
• a plurality of chambers within said reaction mass, into which the flow of drilling mud can be directed,
• a plurality of vanes rigidly attached to the drill string and extending into said chambers, and
• means for selectively directing a flow of mud into said chambers on a selected side of said vanes, to produce a torque between said vanes and said chambers.

A method for generating torsional acoustic waves in a drill string, for the transmission of telemetary data, said method comprising the steps of:

• generating a torque between a reaction mass mounted for limited rotation about a drill string and a generator housing rigidly connected into the drill string, wherein said generating step includes selectively directing drilling mud through fluid coupling means between said reaction mass and said generator housing, to provide a torque between said reaction mass and said generator housing in a desired rotational direction;
• rotating said generator housing and the drill string with respect to said reaction mass, as a result of the generated torque;
• thereby propagating a torsional wave along the drill string, independently of the drill string angular velocity;
• and
• biasing said reaction mass into a neutral position with respect to said generator body, whereby said reaction mass rotates synchronously with said drill string when mud is not being directed through the fluid coupling means.