Hard-Mounted EM Telemetry System for MWD Tool in Bottom Hole Assembly

Abstract

An MWD apparatus has a bottomhole assembly for supporting a tool string and an antenna. The tool string has a sensor and an electromagnetic telemetry device. The tool string affixes in a muleshoe and carrier sub of the assembly using a stinger and fastener. An antenna disposes in an emitter sub of the assembly. The antenna is attached to extend from the tool string so the antenna is in electrical communication with the telemetry device. Finally, the portions of the assembly are connected together, and the antenna is affixed in the uphole portion of the assembly using a conductive landing and one or more fasteners. In this way, the tool string and the antenna are held in tension inside the assembly. The MWD apparatus can be used with an air drilling assembly having an air hammer and a motor coupled downhole of the apparatus. Non-magnetic and regular drill collars can couple uphole of the apparatus, along with a jet sub.

What is claimed is: 
     
         1 . A measurement-while-drilling apparatus, comprising:
 a bottom hole assembly having downhole and uphole portions;   a tool string disposed in the bottom hole assembly and having a first end, the first end engaged at the downhole portion of the bottom hole assembly, the tool string having at least one sensor and having an electromagnetic telemetry device in electrical communication with the at least one sensor; and   an antenna extending in the bottom hole assembly from the tool string and in electrical communication with the electromagnetic telemetry device, the antenna having a second end engaged at the uphole portion of the bottom hole assembly,   wherein the first and second ends affix to the uphole and downhole portions respectively and hold the tool string and the antenna in tension inside the bottom hole assembly.   
     
     
         2 . The apparatus of  claim 1 , wherein the bottom hole assembly comprises a muleshoe sub at the downhole portion, a tool carrier sub coupled to the muleshoe sub, and an emitter sub at the uphole portion coupled to the tool carrier sub. 
     
     
         3 . The apparatus of  claim 2 , wherein the bottom hole assembly comprises a non-magnetic drill collar coupled uphole of the emitter sub. 
     
     
         4 . The apparatus of  claim 1 , wherein the tool string comprises a stinger disposed on the tool string and secured in a muleshoe sub at the downhole portion of the bottom hole assembly. 
     
     
         5 . The apparatus of  claim 4 , wherein a fastener secures the stinger to the muleshoe sub, and wherein the bottom hole assembly comprises a grommet composed of elastomer and engaged between the fastener and the stinger. 
     
     
         6 . The apparatus of  claim 1 , wherein the antenna comprises a conductive rod in electrical communication with the electromagnetic telemetry device. 
     
     
         7 . The apparatus of  claim 6 , wherein the antenna comprises a conductive landing disposed on the conductive rod at the second end of the antenna. 
     
     
         8 . The apparatus of  claim 7 , wherein the conductive rod comprises an uphole threaded end, the conductive landing disposed on the uphole threaded end and held in place against the second end with at least one lock-down fastener threaded on the uphole threaded end. 
     
     
         9 . The apparatus of  claim 6 , wherein the conductive rod comprises a plurality of non-conductive centralizers disposed thereon and centralizing the conductive rod inside the bottom hole assembly. 
     
     
         10 . The apparatus of  claim 6 , wherein the conductive rod comprises a plurality of non-conductive sleeves disposed thereon. 
     
     
         11 . The apparatus of  claim 7 , wherein the bottom hole assembly comprises a beveled shoulder at the second end; and wherein the conductive landing comprises a beveled end engaging the beveled shoulder and centrally holding the second end of the antenna therein. 
     
     
         12 . The apparatus of  claim 11 , wherein one or more lock-down nuts threaded on the second end of the antenna hold the conductive landing engaged with the beveled shoulder. 
     
     
         13 . The apparatus of  claim 1 , wherein the at least one sensor is selected from the group consisting of a gamma ray sensor, a pressure sensor, an inclinometer, and a directional sensor. 
     
     
         14 . The apparatus of  claim 1 , wherein the electromagnetic telemetry device comprises an electromagnetic telemetry transceiver configured to send and receive electromagnetic telemetry signals. 
     
     
         15 . The apparatus of  claim 1 , further comprising a drilling assembly coupled downhole of the bottom hole assembly and drilling an advancing borehole using flow delivered thereto through the bottom hole assembly. 
     
     
         16 . The apparatus of  claim 15 , wherein the drilling assembly comprises:
 an impact hammer operable with the flow delivered thereto; and   a motor coupled uphole of the impact hammer, the motor operable with the delivered flow and imparting rotation to the hammer.   
     
     
         17 . The apparatus of  claim 16 , wherein the motor comprises one or more of: radial bearings with increased clearances of 0.025 to 0.030-in., a ratio of ⅞ lobes for a stator and a rotor of the motor with a number of stages on the rotor being less than or equal to 3, a fit separation of −0.010 to −0.025-in. between the stator and the rotor of the motor, and a stator composed of a nitrile rubber resistant to explosive decompression. 
     
     
         18 . The apparatus of  claim 16 , further comprising a jet sub coupled uphole of the motor, the jet sub diverting at least a portion of the delivered flow to an annulus of the advancing borehole and limiting the rotation imparted by the motor to the hammer. 
     
     
         19 . The apparatus of  claim 18 , wherein the jet sub is coupled uphole of the bottom hole assembly. 
     
     
         20 . A measurement-while-drilling apparatus, comprising:
 a bottom hole assembly having downhole and uphole portions;   a tool string disposed in the bottom hole assembly and having at least one sensor, the tool string having an electromagnetic telemetry device in electrical communication with the at least one sensor;   first means disposed on the tool string for affixing the tool string to the downhole portion of the bottom hole assembly;   an antenna extending in the bottom hole assembly from the tool string and in electrical communication with the electromagnetic telemetry device; and   second means disposed on the antenna for affixing the antenna to the uphole portion of the bottom hole assembly, the first and second means holding the tool string and the antenna in tension inside the bottom hole assembly.   
     
     
         21 . A measurement-while-drilling method, comprising:
 assembling a tool string having at least one sensor and having an electromagnetic telemetry device in electrical communication with the at least one sensor;   affixing the assembled tool string in a first portion of the bottom hole assembly;   attaching an antenna to extend from the tool string;   disposing the antenna in a second portion of the bottom hole assembly;   connecting the first portion to the second portion; and   holding the tool string and the antenna in tension inside the bottom hole assembly by affixing the antenna in the second portion.   
     
     
         22 . The method of  claim 21 , wherein affixing the assembled tool string in the first portion of the bottom hole assembly comprises securing a stinger disposed on the tool string in the first portion. 
     
     
         23 . The method of  claim 21 , wherein attaching the antenna to extend from the tool string comprises attaching a conductive rod in electrical communication with the electromagnetic telemetry system. 
     
     
         24 . The method of  claim 23 , wherein affixing the antenna in the second portion comprises disposing a conductive landing on a threaded end of the antenna and holding the conductive landing against a shoulder in the bottom hole assembly with at least one fastener threaded on the threaded end. 
     
     
         25 . The method of  claim 23 , wherein affixing the antenna in the second portion comprises centralizing the conductive rod in the second portion with a plurality of non-conductive centralizers disposed on the conductive rod. 
     
     
         26 . The method of  claim 23 , wherein affixing the antenna in the second portion comprises isolating portion of the conducive rod inside the second portion with a plurality of non-conductive sleeves disposed on the conductive rod. 
     
     
         27 . The method of  claim 23 , wherein attaching the antenna to extend from the tool string comprises threading a downhole end of the conductive rod to the tool string. 
     
     
         28 . The method of  claim 21 , wherein connecting the first portion to the second portion comprises:
 connecting an emitter sub of the second portion to a carrier sub of the first portion, the emitter sub at least partially holding the antenna therein, the carrier sub at least partially holding the tool string therein.   
     
     
         29 . The method of  claim 28 , wherein the carrier sub comprises a muleshoe housing at the first end. 
     
     
         30 . The method of  claim 21 , wherein the at least one sensor is selected from the group consisting of a gamma ray sensor, a pressure sensor, an inclinometer, and a directional sensor. 
     
     
         31 . The method of  claim 21 , wherein the electromagnetic telemetry device comprises an electromagnetic telemetry transceiver configured to send and receive electromagnetic telemetry signals.