Dual rotor pulser for transmitting information in a drilling system

Abstract

A rotary pulser for transmitting information in a mud pulse telemetry system of a drilling operation. The pulser has two rotors mounted adjacent each other so that obstruction of the passages formed between the blades in one pulser by the blades of the other pulser creates pressure pulses in the drilling fluid. Each rotor is separately controlled and can be rotated continuously in one direction or oscillated. The ability to rotate each rotor separately provides flexibility in the pulser's operating mode, so as to allow more efficient generation of pulses, and also enhances the ability of the pulser to clear debris that would otherwise jam or obstruct the pulser.

What is claimed: 
     
         1 . A pulser configured to transmit information from a portion of a drill string operating at a down hole location in a well bore toward a location proximate the surface of an earthen formation, the pulser comprising:
 an outer housing assembly;   a first stator mounted to the outer housing assembly, the first stator including a first stator passage through which drilling fluid can flow;   a first rotating element adjacent to the first stator, the first rotating element including a first passage through which the drilling fluid can flow, wherein the first rotating element is rotatable with respect to the first stator and the outer housing assembly to at least partially block the first stator passage;   a second stator mounted to the outer housing assembly, the second stator including a second stator passage through which drilling fluid can flow;   a second rotating element adjacent to the second stator, the second rotating element including a second passage through which the drilling fluid can flow, wherein the second rotating element is rotatable with respect to second stator and the outer housing assembly to at least partially block the second stator passage; and   a motor assembly coupled to the first rotating element and the second rotating element to drive rotation of the first rotating element and the second rotating element, such that, 1) rotation of the first rotating element relative to the first stator creates first pressure pulses in the drilling fluid when the drilling fluid is flowing through the first passage and the first stator passage, and 2) rotation of the second rotating element relative to the second stator creates second pressure pulses in the drilling fluid when the drilling fluid is flowing through the second passage and the second stator passage, wherein the information is encoded in the first and second pressure pulses.   
     
     
         2 . The pulser according to  claim 1 , further comprising a controller configured to operate a first motor and a second motor. 
     
     
         3 . The pulser according to  claim 2 , wherein the controller is configured to operate the first and second motors so as to selectively rotate one of the first motor and the second motor while inhibiting rotation of the other of the first motor and the second motor. 
     
     
         4 . The pulser according to  claim 2 , wherein the controller is configured to cause the first motor and the second motor to continuously rotate the first rotating element and the second rotating element, respectively, in a similar rotational direction. 
     
     
         5 . The pulser according to  claim 2 , wherein the controller is configured to cause the first motor and the second motor to continuously rotate the first rotating element and second rotating element, respectively, in different rotational directions. 
     
     
         6 . The pulser according to  claim 2 , wherein the first rotating element and the second rotating element rotate at different rotational speeds. 
     
     
         7 . The pulser according to  claim 2 , wherein the controller is configured to cause the first motor and the second motor to oscillate the first rotating element and second rotating element, respectively. 
     
     
         8 . The pulser according to  claim 7 , wherein the first rotating element and the second rotating element oscillate at different speeds.