Intelligent drilling riser telemetry system

Abstract

An intelligent drilling riser telemetry system includes a mud pulse telemetry transmitter deployed in a drill string. At least one annular pressure sensor is deployed on a drilling riser and is configured to sense mud pulse telemetry signals in an annular region thereof. A surface processor is in electronic communication with the annular pressure sensor via an electrical transmission line that extends along a length of the drilling riser from the annular pressure sensor to the drilling rig. The processor is configured to decode a transmitted mud pulse telemetry signal.

What is claimed is: 
     
         1 . A mud pulse telemetry method comprising:
 (a) deploying a drill string in an offshore drilling riser, the drill string including a mud pulse telemetry transmitter, the drilling riser including an annular pressure sensor in electronic communication with a surface processor via an electrical transmission line;   (b) causing the mud pulse telemetry transmitter to transmit a series of pressure pulses in the drill string;   (c) detecting the pressure pulses in an annular region of the drilling riser via the annular pressure sensor;   (d) transmitting the detected pressure pulses to the surface processor via the electrical transmission line; and   (e) causing the surface processor to decode the pressure pulses.   
     
     
         2 . The method of  claim 1 , wherein (d) further comprises (i) digitizing the detected pressure pulses and (ii) transmitting said digitized pressure pulses to the surface processor via the electrical transmission line. 
     
     
         3 . The method of  claim 1 , wherein the annular pressure sensor is deployed at a lower end of the drilling riser. 
     
     
         4 . The method of  claim 1 , wherein:
 the drilling riser comprises a plurality of axially spaced annular pressure sensor in electronic communication with the surface processor; and   (c) further comprises detecting the pressure pulses at each of the plurality of annular pressure sensors.   
     
     
         5 . The method of  claim 4 , further comprising velocity filtering the pressure pulses received at the plurality of axially spaced annular pressure sensors to separate upwardly travelling acoustic waves from downwardly travelling acoustic waves. 
     
     
         6 . The method of  claim 5 , wherein the velocity filtering comprises transforming the pressure pulses received at the plurality of axially spaced annular pressure sensors to an FK plane. 
     
     
         7 . The method of  claim 6 , wherein the velocity filtering further comprises applying a frequency band filter to a wedge of data in the FK plane. 
     
     
         8 . The method of  claim 4 , further comprising stacking the pressure pulses received at the plurality of axially spaced annular pressure sensors to reduce random noise. 
     
     
         9 . The method of  claim 1 , wherein the pressure pulses transmitted in (b) encode data via phase modulation and the surface processor uses a quadrature phase shift keying algorithm to decode the pressure pulses in (e). 
     
     
         10 . A mud pulse telemetry system comprising:
 a mud pulse telemetry transmitter deployed in a drill string, the drill string deployed in a drilling riser coupled to an offshore drilling rig.   at least one annular pressure sensor deployed on the drilling riser, the pressure sensor configured to sense mud pulse telemetry signals in an annular region of the drilling riser; and   a surface processor in electronic communication with the annular pressure sensor via an electrical transmission line that extends along a length of the drilling riser from the annular pressure sensor to the drilling rig, the processor configured to decode mud pulse telemetry signals transmitted by the mud pulse telemetry transmitter.   
     
     
         11 . The system of  claim 10 , wherein:
 the drilling riser comprises a plurality of elongated riser sections connected end to end; and   the electrical transmission line comprises a plurality of electrically conductive segments inductively coupled to one another.   
     
     
         12 . The system of  claim 10 , wherein the at least one annular pressure sensor is coupled to an outer surface of a riser body and is in hydraulic communication with a riser annulus via a hole in the riser body. 
     
     
         13 . The system of  claim 10 , comprising a plurality of axially spaced annular pressure sensors. 
     
     
         14 . The system of  claim 13 , comprising at least four equi-spaced annular pressure sensors. 
     
     
         15 . The system of  claim 14 , wherein the annular pressure sensors are axially spaced apart from one another less than about one quarter of a wavelength of a transmitted mud pulse telemetry carrier signal.