An apparatus, system and method for actuating downhole tools in subsea drilling applications

Abstract

A downhole logging tool and method of use for analysing portions of a seafloor borehole in seafloor drilling operations are provided. The downhole logging tool h an underwater chassis housing a power system and sensors including at least a conductivity sensor and a magnetic susceptibility sensor which, preferably, analyse the walls of the borehole. An automatically actuated switch, preferably actuated magnetically, provides power to the sensors from the power system when the downhole logging tool is not located in a designated portion of a seafloor drilling rig (e.g. when the tool is in use traversing a borehole) and removes power when the downhole logging tool is located in the designated portion of the seafloor drilling rig (e.g. when the downhole tool is not in use).

1 . A downhole logging tool for use in a seafloor borehole of seafloor drilling operations, the downhole logging tool comprising:
 an underwater chassis comprising electronic components and a power system, the electronic components including sensors; and   an automatically actuated switch that selectively provides power from the power system to the electronic components;   wherein the sensors include at least a conductivity sensor and a magnetic susceptibility sensor, and the automatically actuated switch is actuated to remove power from the electronic components when the downhole logging tool is located in a designated portion of a seafloor drilling rig of seafloor drilling operations and to provide power to the electronic components when the downhole logging tool is not located in the designated portion of a seafloor drilling rig.   
     
     
         2 . The downhole logging tool of  claim 1 , wherein the automatically actuated switch includes a magnetic switch that is actuated by proximity to a magnetic source. 
     
     
         3 . The downhole logging tool of  claim 2 , wherein the magnetic source is located in the designated portion of the seafloor drilling rig. 
     
     
         4 . The downhole logging tool of  claim 2 , wherein the magnetic source is located adjacent a downhole logging tool storage rack of the drilling rig. 
     
     
         5 . The downhole logging tool of  claim 2 , wherein the magnetic switch is normally open and is closed by the magnetic field of the magnetic source. 
     
     
         6 . The downhole logging tool of  claim 2 , wherein the magnetic switch is a reed sensor that is part of an automatically actuated switch circuit that includes at least one transistor. 
     
     
         7 . The downhole logging tool of  claim 6 , wherein the transistor is electrically connected to the power source and the reed sensor switches the transistor to selectively provide power to the electronic components. 
     
     
         8 . The downhole logging tool of  claim 1 , wherein the electronic components include a data transfer system in communication with the sensors. 
     
     
         9 . The downhole logging tool of  claim 1 , wherein the sensors comprise radial measurement sensors that conduct measurements of the walls of the borehole. 
     
     
         10 . The downhole logging tool of  claim 1 , wherein the sensors of the downhole logging tool further comprise a temperature sensor, a resistivity sensor, and/or a natural gamma sensor. 
     
     
         11 . The downhole logging tool of  claim 10 , wherein the resistivity sensor is an inductive conductivity sensor. 
     
     
         12 . The downhole logging tool of  claim 11 , wherein the inductive conductivity sensor is a dual coil inductive conductivity sensor or a coil-focused inductive conductivity sensor. 
     
     
         13 . The downhole logging tool of  claim 1 , wherein the underwater chassis comprises a mating portion that releasably secures to a corresponding mating portion of the seafloor drilling rig. 
     
     
         14 . The downhole logging tool of  claim 13 , wherein the mating portion includes a latch head to mate the downhole logging tool to a wireline system. 
     
     
         15 . The downhole logging tool of  claim 13 , wherein the mating portion includes an adapter to mate the downhole logging tool to a drill string. 
     
     
         16 . The downhole logging tool of  claim 1 , wherein the power system comprises a battery. 
     
     
         17 . The downhole logging tool of  claim 16 , wherein the battery is rechargeable and the power system further comprise a battery charging system. 
     
     
         18 . The downhole logging tool of  claim 17 , wherein the battery charging system charges the batteries inductively from the seafloor drilling rig. 
     
     
         19 . A seafloor drilling rig comprising a downhole logging tool as claimed in  claim 1 . 
     
     
         20 . A system of utilising a downhole logging tool in seafloor drilling operations comprising:
 a downhole logging tool, for traversing a seafloor borehole, with a power system, sensors, and an automatically actuated switch, wherein the sensors include at least a conductivity sensor and a magnetic susceptibility sensor and wherein the automatically actuated switch selectively provides power from the power system to sensors of the downhole logging tool;   the automatically actuated switch being configured to activate the downhole logging tool when leaving a designated portion of a seafloor drilling rig and deactivate the downhole logging tool when entering the designated portion of the seafloor drilling rig.   
     
     
         21 . A method of utilising a downhole logging tool in seafloor drilling operations comprising the steps of:
 selecting a downhole logging tool to traverse a seafloor borehole;   manoeuvring the selected downhole logging tool from a designated portion of a seafloor drilling rig; and   automatically actuating an automatically actuated switch of the downhole logging tool to activate the downhole logging tool when leaving the designated portion of a drilling rig and to deactivate the downhole logging tool when entering the designated portion of the seafloor drilling rig.   
     
     
         22 . The method of  claim 21 , wherein the method further comprises the steps of:
 connecting the downhole logging tool to a wireline;   lowering the downhole logging tool down the seafloor borehole through a drill string;   seating the downhole logging tool in a receiving portion of the lowermost drill string;   disconnecting and retracting the wireline; and   conducting measurements on the downhole tool as the drill string is removed from the borehole.   
     
     
         23 . The method of  claim 21 , wherein the downhole logging tool has sensors including at least a conductivity sensor and a magnetic susceptibility sensor. 
     
     
         24 . The method of  claim 21 , wherein the downhole logging tool conducts radial measurements of walls of the borehole. 
     
     
         25 . The method of  claim 21 , wherein the downhole logging tool is a downhole logging tool as claimed in  claim 1 .