Variable Rate Mud Pulse Telemetry

Abstract

A drilling system includes a drill string and surface equipment. The drill string includes a mud pulse transmitter. The mud pulse transmitter is configured to provide a first mud pulse transmission at a first rate responsive to drilling, and provide a second mud pulse transmission at a second rate responsive to not drilling. The surface equipment is coupled to the drill string. The surface equipment includes a mud pulse receiver. The mud pulse receiver is configured to receive the first mud pulse transmission at the first rate responsive to drilling, and receive the second mud pulse transmission at the first rate responsive to drilling. The second rate is higher than the first rate.

What is claimed is: 
     
         1 . A drilling system comprising:
 a drill string comprising:
 a mud pulse transmitter configured to:
 provide a first mud pulse transmission at a first rate responsive to drilling; and 
 provide a second mud pulse transmission at a second rate responsive to not drilling; 
 
   surface equipment coupled to the drill string, the surface equipment comprising:
 a mud pulse receiver configured to:
 receive the first mud pulse transmission at the first rate responsive to drilling; and 
 receive the second mud pulse transmission at the second rate responsive to not drilling; 
 
   wherein the second rate is higher than the first rate.   
     
     
         2 . The drilling system of  claim 1 , wherein the mud pulse transmitter is configured to:
 transmit drilling data at the first rate; and   transmit survey data at the second rate.   
     
     
         3 . The drilling system of  claim 2 , wherein the mud pulse receiver is configured to:
 receive the drilling data at the first rate; and   receive the survey data at the second rate.   
     
     
         4 . The drilling system of  claim 2 , wherein the mud pulse transmitter is configured to enable transmission at the first rate responsive to an end of transmission of a frame of the survey data. 
     
     
         5 . The drilling system of  claim 2 , wherein the mud pulse receiver is configured to enable reception at the first rate responsive to reception of a complete frame of the survey data. 
     
     
         6 . The drilling system of  claim 1 , wherein the mud pulse receiver is configured to enable reception at the second rate responsive to a resumption of drilling fluid circulation in the drill string. 
     
     
         7 . The drilling system of  claim 1 , wherein the mud pulse transmitter is configured to enable transmission at the second rate responsive to detection of a resumption of drilling fluid circulation in the drill string. 
     
     
         8 . A method for downhole communication, comprising:
 providing, by a downhole mud pulse transmitter, a first mud pulse transmission at a first rate responsive to drilling;   receiving, by a surface mud pulse receiver, the first mud pulse transmission at the first rate responsive to drilling;   providing, by the downhole mud pulse transmitter, a second mud pulse transmission at a second rate responsive to not drilling; and   receiving, by the surface mud pulse receiver, the second mud pulse transmission at the second rate responsive to not drilling.   
     
     
         9 . The method of  claim 8 , further comprising:
 providing a drill frame including drilling data in the first mud pulse transmission; and   providing a survey frame including survey data in the second mud pulse transmission.   
     
     
         10 . The method of  claim 9 , further comprising enabling, by the downhole mud pulse transmitter, transmission at the first rate responsive to an end of transmission of the survey frame. 
     
     
         11 . The method of  claim 9 , further comprising enabling, by the mud pulse receiver, reception at the first rate responsive to reception of the survey frame. 
     
     
         12 . The method of  claim 8 , further comprising enabling, by the mud pulse receiver, reception at the second rate responsive to a resumption of drilling fluid circulation in a drill string including the downhole mud pulse transmitter. 
     
     
         13 . The method of  claim 8 , further comprising enabling transmission at the second rate responsive to detection of a resumption of drilling fluid circulation in a drill string. 
     
     
         14 . The method of  claim 8 , further comprising resuming drilling responsive to the receiving, by the surface mud pulse receiver, of the second mud pulse transmission. 
     
     
         15 . The method of  claim 8 , wherein the second rate is higher than the first rate. 
     
     
         16 . A downhole tool comprising:
 a mud pulse transmitter comprising:
 a pulser configured to modulate a pressure of drilling fluid flowing through the downhole tool; 
 an encoder coupled to the pulser, the encoder configured to control the pulser to:
 provide a first mud pulse transmission at a first rate responsive to a resumption of drilling fluid circulation through the downhole tool; and 
 provide a second mud pulse transmission at a second rate responsive to completion of the first mud pulse transmission. 
 
   
     
     
         17 . The downhole tool of  claim 16 , wherein the first rate is higher than the second rate. 
     
     
         18 . The downhole tool of  claim 16 , wherein the first rate is about 1.5 times the second rate. 
     
     
         19 . The downhole tool of  claim 16 , wherein the encoder is configured to:
 provide survey data for transmission at the first rate; and   provide drilling data for transmission at the second rate.   
     
     
         20 . The downhole tool of  claim 16 , wherein the encoder is configured to control the pulser to provide a synchronization pattern transmission at the first rate prior to the first mud pulse transmission.