Borehole surveying tool deployment

Abstract

An apparatus for use in a downhole survey in conjunction with core sampling comprises a body adapted to receive a downhole surveying instrument, whereby the downhole surveying instrument can be conveyed along a borehole with the apparatus and operated in the borehole.

1 . Apparatus for use in a downhole survey in conjunction with core sampling, the apparatus comprising a body adapted to receive a downhole surveying instrument, whereby the downhole surveying instrument can be conveyed along a borehole with the apparatus and operated in the borehole. 
     
     
         2 . The apparatus defined by  claim 1 , wherein the downhole surveying instrument comprises a downhole survey tool or a component thereof. 
     
     
         3 . The apparatus defined by  claim 2 , wherein the downhole tool comprises one or more sensor devices selected from a group of sensor devices comprising an: orthogonal accelerometer; magnetometer; gyroscope; and a MEMS (microelectromechanical) gyro sensor. 
     
     
         4 . The apparatus defined by any one of the preceding claims, wherein the body, or at least relevant parts thereof, are made of material or materials which do not interfere magnetically with downhole surveying instrument. 
     
     
         5 . The apparatus defined by  claim 4 , wherein the body, or at least relevant parts thereof, are made of material which is non-magnetic. 
     
     
         6 . The apparatus defined by any one of the preceding claims, wherein the body incorporates a cavity for accommodating the downhole surveying instrument. 
     
     
         7 . The apparatus defined by any one of the preceding claims, wherein the body is configured to facilitate installation of the downhole surveying instrument in the cavity. 
     
     
         8 . The apparatus defined by  claim 7 , wherein the body is constructed in two or more parts, with one part being selectively separable from another part to provide access to the cavity. 
     
     
         9 . The apparatus defined by any one of the preceding claims, wherein the body is adapted to provide cushioning to afford some impact protection for the surveying instrument. 
     
     
         10 . The apparatus defined by  claim 9 , wherein the body is configured to cushion impact forces following descent into a borehole. 
     
     
         11 . The apparatus defined by  claim 9  or  10 , wherein the cushioning is provided by a cushioning mechanism incorporated in the body. 
     
     
         12 . The apparatus defined by  claim 11 , wherein the cushioning mechanism comprises an elastic structure for absorbing a shock impact. 
     
     
         13 . The apparatus defined by  claim 12 , wherein the elastic structure comprises a spring. 
     
     
         14 . The apparatus defined by  claim 12  or  13 , wherein the cushioning mechanism further comprises a shock absorber for damping the spring oscillations. 
     
     
         15 . The apparatus defined by any one of the preceding claims, wherein the apparatus further comprises at least a portion of a magnetic braking system. 
     
     
         16 . The apparatus defined by any one of the preceding claims, wherein the apparatus further comprises provision for controlled positioning thereof within the borehole for operation of the surveying instrument. 
     
     
         17 . The apparatus defined by  claim 16 , wherein the provision for controlled positioning within the borehole for operation of the surveying instrument comprises means for engaging the surrounding portion of a drill string to provide stabilization with respect to the drill string. 
     
     
         18 . The apparatus defined by  claim 17 , wherein the engaging means may be adapted to support the apparatus within the surrounding portion of the drill string in a circumferentially centred manner. 
     
     
         19 . The apparatus defined by  18 , wherein the engaging means comprises radially disposed arms biased outwardly to contact sides of the drill string, thus centrally positioning the apparatus within the surrounding portion of the drill string. 
     
     
         20 . The apparatus defined by  claim 19 , wherein the arms each include an outer contact portion configured for contact with the inner wall of the surrounding portion of the drill string. 
     
     
         21 . The apparatus defined by any one of  claims 17  to  20 , wherein the engaging means is configured to engage the drill string for movement therealong as the apparatus is raised or lowered within the borehole. 
     
     
         22 . The apparatus defined by any one of  claims 17  to  20 , wherein the engaging means is adapted for movement between collapsed and extended conditions, whereby in the collapsed condition it is clear of the internal wall of the drill string for movement therealong and in the extended condition it is in engagement with the drill string for controlled positioning of the apparatus within the borehole to provide stable support for operation of the surveying instrument. 
     
     
         23 . The apparatus defined by any one of  claims 17  to  22 , wherein the apparatus further comprises actuation means for actuating the engaging means. 
     
     
         24 . The apparatus defined by any one of the preceding claims, wherein the apparatus is adapted to initiate operation of the downhole surveying instrument. 
     
     
         25 . The apparatus defined by any one of the preceding claims, wherein the apparatus is selected from a group of apparatus comprising: an inner tube assembly of a core drill; an overshot assembly; or an arrangement such as a sub or a drop tool assembly adapted for attachment to an inner tube assembly and/or to an overshot assembly. 
     
     
         26 . An inner tube assembly comprising a body having an upper portion adapted for connection to a retrieval system and a lower portion adapted to receive a core sample during a drilling operation, the body being adapted to receive a downhole surveying instrument, whereby the downhole surveying instrument can be conveyed along a borehole with the inner tube assembly and operated in the borehole. 
     
     
         27 . The inner tube assembly defined by  claim 26 , wherein the retrieval system comprises an overshot assembly attached to the end of a wireline. 
     
     
         28 . The inner tube assembly defined by  claim 26  or  27 , wherein the overshot assembly incorporates means operable for controlled positioning of the body within the borehole for operation of the surveying instrument. 
     
     
         29 . The inner tube assembly defined by  claim 28 , wherein the means operable for controlled positioning of the body within the borehole comprises means for controlling positioning of the overshot assembly within the borehole. 
     
     
         30 . The inner tube assembly defined by  claim 29 , wherein the means operable for controlled positioning of the body within the borehole comprises means for engaging the surrounding portion of a drill string to stabilise the overshot assembly with respect to the drill string. 
     
     
         31 . The inner tube assembly defined by  claim 30 , wherein the engaging means is adapted to support the overshot assembly within the surrounding portion of the drill string in a circumferentially centred manner. 
     
     
         32 . The inner tube assembly defined by  claim 30  or  31 , wherein the engaging means comprises radially disposed arms biased outwardly to contact sides of the drill string, thus centrally positioning the overshot assembly within the surrounding portion of the drill string. 
     
     
         33 . The inner tube assembly defined by  claim 32 , wherein the arms each include an outer contact portion configured for contact with the inner wall of the surrounding portion of the drill string. 
     
     
         34 . The inner tube assembly defined by any one of  claims 30  to  33 , wherein the engaging means is configured to engage the drill string for movement therealong as the overshot assembly is raised or lowered within the borehole. 
     
     
         35 . The inner tube assembly defined by  claim 34 , wherein the engaging means comprises a fixed structure configured as a carriage for movement along the internal wall of the drill string. 
     
     
         36 . The inner tube assembly defined by any one of  claims 30  to  33 , wherein the engaging means is adapted for movement between collapsed and extended conditions, whereby in the collapsed condition it is clear of the internal wall of the drill string for movement therealong and in the extended condition it is in engagement with the drill string for controlled positioning of the overshot assembly within the borehole to provide stable support for operation of the surveying instrument. 
     
     
         37 . An overshot assembly comprising a body having an upper portion adapted for connection to a wireline and a lower portion adapted to be releasably connected to an inner tube assembly, the body being adapted to receive a downhole surveying instrument, whereby the downhole surveying instrument can be conveyed along a borehole with the overshot assembly and operated in the borehole. 
     
     
         38 . The overshot assembly defined by  claim 37 , wherein the downhole surveying instrument comprises a downhole survey tool or a component thereof. 
     
     
         39 . The overshot assembly defined by  claim 38 , wherein the downhole tool comprises one or more sensor devices selected from a group of sensor devices comprising an orthogonal accelerometer; magnetometer; gyroscope; and a MEMS (microelectromechanical) gyro sensor. 
     
     
         40 . The overshot assembly defined by any one of  claims 37  to  39 , wherein the body, or at least relevant parts thereof, are made of material or materials which do not interfere magnetically with downhole surveying instrument. 
     
     
         41 . The overshot assembly defined by  claim 40 , wherein the body, or at least relevant parts thereof, are made of material which is non-magnetic. 
     
     
         42 . The overshot assembly defined by any one of  claims 37  to  41  wherein the downhole surveying instrument is operable within the borehole while the overshot assembly is connected to the inner tube assembly. 
     
     
         43 . The overshot assembly defined by any one of  claims 37  to  42  further comprising means operable for controlled positioning of the body within the borehole for operation of the surveying instrument. 
     
     
         44 . The overshot assembly defined by  claim 43  wherein the means operable for controlled positioning of the body within the borehole comprises means for engaging the surrounding drill string to stabilise the body. 
     
     
         45 . The overshot assembly defined by  claim 44  wherein the engaging means is adapted to support the body within the drill string in a circumferentially centred manner. 
     
     
         46 . The overshot assembly defined by  claim 45  wherein the engaging means is configured as a centraliser. 
     
     
         47 . The overshot assembly defined by  claim 45  or  46 , wherein the engaging means comprise radially disposed arms biased outwardly to contact sides of the drill string, thus centrally positioning the body within the drill string. 
     
     
         48 . The overshot assembly defined by  claim 47 , wherein the arms each include an outer contact portion configured for contact with the inner wall of the surrounding drill string. 
     
     
         49 . The overshot assembly defined by any one of  claims 44  to  48 , wherein the engaging means is configured to engage the drill string for movement therealong as the overeshot assembly is raised or lowered within the borehole 
     
     
         50 . The overshot assembly defined by  claim 49 , wherein the engaging means comprises a fixed structure configured as a carriage for movement along the internal wall of the drill string. 
     
     
         51 . The overshot assembly defined by any one of  claims 44  to  48 , wherein the engaging means is adapted for movement between collapsed and extended conditions, whereby in the collapsed condition it is clear of the internal wall of the drill string for movement therealong and in the extended condition it is in engagement with the drill string for controlled positioning of the body within the borehole to provide stable support for operation of the survey instrument. 
     
     
         52 . The overshot assembly defined by any one of  claims 37  to  51 , wherein the body incorporates a cavity for accommodating the downhole instrument. 
     
     
         53 . The overshot assembly defined by  claim 52 , wherein the body is configured to facilitate installation of the downhole surveying instrument in the cavity. 
     
     
         54 . The overshot assembly defined by  claim 53 , wherein the body comprises two or more parts, with one part being selectively separable from another part to provide access to the compartment. 
     
     
         55 . The overshot assembly defined by any one of  claims 37  to  54 , wherein the body is adapted to provide cushioning to afford some impact protection for the surveying instrument. 
     
     
         56 . The overshot assembly defined by  claim 55 , wherein the body is configured to cushion impact forces when moving into contact with a downhole inner tube assembly following descent on the wireline. 
     
     
         57 . The overshot assembly defined by  claim 55  or  56 , wherein the cushioning is provided by a cushioning mechanism incorporated in the body. 
     
     
         58 . The overshot assembly defined by  claim 57 , wherein the cushioning mechanism comprises an elastic structure for absorbing a shock impact. 
     
     
         59 . The overshot assembly defined by  claim 58 , wherein the elastic structure comprises a spring. 
     
     
         60 . The overshot assembly defined by  claim 58  or  59 , wherein the cushioning mechanism further comprises a shock absorber for damping spring oscillations. 
     
     
         61 . The overshot assembly according to any one of  claims 57  to  60 , wherein the cushioning mechanism comprises a parachute or other controlled descent system or method. 
     
     
         62 . The overshot assembly defined by any one of  claims 57  to  61 , wherein the cushioning mechanism is incorporated within the body between two parts thereof. 
     
     
         63 . The overshot assembly defined by any one of  claims 37  to  62 , wherein the overshot assembly further comprises at least a portion of a magnetic braking system for slowing the overshot assembly. 
     
     
         64 . The overshot assembly defined by any one of  claims 37  to  63 , wherein the lower portion of the body incorporates a latching mechanism for releasable connection to a mating formation on the inner core tube assembly. 
     
     
         65 . The overshot assembly defined by  claim 64 , wherein the body incorporates an actuator for actuating the latching mechanism to engage/disengage the formation upon engagement between the overshot assembly and the inner core tube assembly. 
     
     
         66 . The overshot assembly defined by any one of  claims 37  to  65 , wherein the overshot assembly is provided with a means for allowing a tool face of the downhole surveying instrument to be transferred to an external surface of the overshot assembly. 
     
     
         67 . The overshot assembly defined by  claim 66 , wherein the overshot assembly is provided with a means for allowing the tool face to be transferred to the inner tube assembly. 
     
     
         68 . Apparatus adapted for connection to an inner tube assembly, the apparatus comprising a body being adapted to receive a downhole surveying instrument, whereby the downhole surveying instrument can be conveyed along a borehole with the inner tube assembly and operated in the borehole. 
     
     
         69 . A drop tool assembly comprising a body having an upper portion adapted to be releasably connected to a retrieval system and a lower portion adapted to be releasably connected to an inner tube assembly, the body being adapted to receive a downhole surveying instrument, whereby the downhole surveying instrument can be conveyed along a borehole with the drop tool assembly and operated in the borehole. 
     
     
         70 . The drop tool assembly defined by  claim 69 , wherein the retrieval system comprises an overshot assembly attached to the end of a wireline. 
     
     
         71 . The drop tool assembly defined by  claim 69  or  70 , wherein the drop tool assembly incorporates means operable for controlled positioning of the body within the borehole for operation of the surveying instrument. 
     
     
         72 . The drop tool assembly defined by  claim 71 , wherein the means operable for controlled positioning of the body within the borehole may comprises means for engaging the surrounding drill string to stabilise the body. 
     
     
         73 . The drop tool assembly defined by  claim 72 , wherein the engaging means is adapted to support the body within the drill string in a circumferentially centred manner. 
     
     
         74 . The drop tool assembly defined by  claim 73 , wherein the engaging means is configured as a centraliser. 
     
     
         75 . The drop tool assembly defined by any one of  claims 72  to  74 , wherein the engaging means comprises radially disposed arms biased outwardly to contact sides of the drill string, thus centrally positioning the body within the drill string. 
     
     
         76 . The drop tool assembly defined by  claim 75 , wherein the arms each include an outer contact portion configured for contact with the inner wall of the surrounding drill string. 
     
     
         77 . The drop tool assembly defined by any one of  claims 72  to  76 , wherein the engaging means is configured, to engage the drill string for movement therealong as the drop tool assembly is raised or lowered within the borehole. 
     
     
         78 . The drop tool assembly defined by  claim 77 , wherein the engaging means comprises a fixed structure configured as a carriage for movement along the internal was of the drill string. 
     
     
         79 . The drop tool assembly defined by any one of  claims 72  to  76 , wherein the engaging means is adapted for movement between collapsed and extended conditions, whereby in the collapsed condition it is clear of the internal wall of the drill string for movement therealong and in the extended condition it is in engagement with the drill string for controlled positioning of the body within the borehole to provide stable support for operation of the surveying instrument. 
     
     
         80 . The drop tool assembly defined by any one of  claims 69  to  79 , wherein the body incorporates a cavity for accommodating the downhole surveying instrument. 
     
     
         81 . The drop tool assembly defined by  claim 80 , wherein the body is configured to facilitate installation of the downhole surveying instrument in the cavity. 
     
     
         82 . The drop tool assembly defined by  claim 81 , wherein the body is constructed in two or more parts, with one part being selectively separable from another part to provide access to the cavity. 
     
     
         83 . The drop tool assembly defined by any one of  claims 69  to  82 , wherein the drop tool assembly further comprises at least a portion of a magnetic braking system. 
     
     
         84 . The drop tool assembly defined by any one of  claims 69  to  83 , wherein the body has an upper portion adapted to be releasably connected to an overshot assembly, and a lower portion adapted to be releasably connected to an inner tube assembly. 
     
     
         85 . The drop tool assembly defined by  claim 84 , wherein the lower portion of the body incorporates a latching mechanism for releasable connection to a mating formation on the inner tube assembly. 
     
     
         86 . The drop tool assembly defined by  claim 85 , wherein the body incorporates an actuator for actuating the latching mechanism to engage the formation upon engagement between the drop tool assembly and the inner core tube. 
     
     
         87 . The drop tool assembly defined by any one of  claims 84  to  86 , wherein the upper portion of the body incorporates a mating formation. 
     
     
         88 . The drop tool assembly defined by any one of  claims 69  to  87 , wherein the downhole surveying instrument comprises a downhole surveying tool or a component thereof. 
     
     
         89 . The drop tool assembly defined by  claim 88 , wherein the downhole tool comprises one or more sensor devices selected from a group of sensor devices comprising an: orthogonal accelerometer; magnetometer; gyroscope; and a MEMS (microelectromechanical) gyro sensor. 
     
     
         90 . The drop tool assembly defined by any one of  claims 69  to  89 , wherein the body, or at least relevant parts thereof, is made of material or materials which do not interfere magnetically with the geo-magnetic device. 
     
     
         91 . The drop tool assembly defined by  claim 90 , wherein the body or at least relevant parts thereof are made of material which is non-magnetic. 
     
     
         92 . The drop tool assembly defined by any one of  claims 69  to  91 , wherein the downhole surveying instrument is operable within the borehole either while the drop tool assembly is connected to the inner tube assembly, or when the drop tool assembly is not connected to the inner tube assembly. 
     
     
         93 . The drop tool assembly defined by any one of  claims 69  to  92 , wherein the drop tool assembly is provided with a means for allowing a tool face of the downhole surveying instrument to be effectively transferred to an external surface of the drop tool assembly. 
     
     
         94 . The drop tool assembly defined by  claim 93 , wherein the drop tool assembly is provided with a means for allowing the tool face to be adjustably transferred to the inner tube assembly. 
     
     
         95 . The drop tool assembly defined by any one of  claims 69  to  92 , wherein the drop tool assembly also comprises a water pressure activation system for indicating when the drop tool assembly has landed or otherwise reached its final position within a borehole. 
     
     
         96 . The drop tool assembly defined by  claim 95 , wherein the water pressure activation system is operable to activate/deactivate the downhole surveying instrument. 
     
     
         97 . A downhole assembly comprising an inner tube assembly according to any one of  claims 26  to  36  in combination with an overshot assembly. 
     
     
         98 . The downhole assembly defined by  claim 97 , wherein the downhole assembly further comprises a release system for allowing the overshot assembly to be released from the inner tube assembly while the overshot assembly and the inner tube assembly are located downhole. 
     
     
         99 . The downhole assembly defined by  claim 97  or  98 , wherein the downhole assembly also comprises a synchronisation system for allowing the overshot assembly to be connected to the inner tube assembly so that a predetermined tool face of the overshot assembly is synchronised to the inner tube assembly. 
     
     
         100 . The downhole assembly defined by  claim 99 , wherein the synchronisation system comprises a profiled portion of the overshot assembly and a profiled portion of the inner tube assembly, the profiled portions being configured to engage with each other such that the overshot assembly is able to rotate relative to the inner tube assembly into a home position under its own weight or with minimal thrust. 
     
     
         101 . The downhole assembly defined by  claim 100 , wherein each profiled portion comprises a respective mule shoe. 
     
     
         102 . The downhole assembly defined by any one of  claims 97  to  101 , wherein the downhole assembly further comprises a locking system for mechanically locking the inner tube assembly to inturn synchronise to a tool face of the overshot assembly. 
     
     
         103 . The downhole assembly defined by  claim 102 , wherein the locking system comprises a flow clutch. 
     
     
         104 . The downhole assembly defined by any one of  claims 97  to  101 , wherein a tool face position of the inner tube assembly is able to be synchronised to the overshot assembly by wireless transmission. 
     
     
         105 . The downhole assembly defined by any one of  claims 97  to  104 , wherein the overshot assembly comprises means operable for controlled positioning of the body within the borehole for operation of the surveying instrument. 
     
     
         106 . A downhole assembly comprising a drop tool assembly defined by any one of  claims 69  to  96  in combination with at least one of an inner tube assembly and an overshot assembly. 
     
     
         107 . The downhole assembly defined by  claim 106 , wherein the downhole assembly also comprises a release system for allowing the drop tool assembly to be released form the inner tube assembly while the drop tool assembly is located down hole. 
     
     
         108 . The downhole assembly defined by  claim 106  or  107 , wherein the downhole assembly also comprises a synchronisation system for allowing the drop tool assembly to be connected to the inner tube assembly so that a predetermined tool face of the drop tool assembly is synchronised to the inner tube assembly. 
     
     
         109 . The downhole assembly defined by  claim 108 , wherein the synchronisation system comprises a profiled portion of the drop tool assembly and a profiled portion of the inner tube assembly, the profiled portions being configured to engage with each other such that the drop tool assembly is able to rotate relative to the inner tube assembly into a home position under its own weight or with minimal thrust. 
     
     
         110 . The downhole assembly defined by  claim 109 , wherein each profiled portion comprises a respective mule shoe. 
     
     
         111 . The downhole assembly defined by any one of  claims 106  to  110 , wherein the downhole assembly further comprises a locking system for mechanically locking the inner tube assembly to inturn synchronise to a tool face of the drop tool assembly. 
     
     
         112 . The downhole assembly defined by  claim 111 , wherein the locking system comprises a flow clutch. 
     
     
         113 . The downhole assembly defined by any one of  claims 106  to  110 , wherein a tool face position of the inner tube assembly is able to be synchronised to the drop tool assembly by wireless transmission. 
     
     
         114 . A method of conducting a borehole surveying operation using a surveying instrument accommodated in an apparatus defined by any one of  claims 1  to  25 . 
     
     
         115 . A method of conducting a borehole surveying operation using a surveying instrument accommodated in an inner tube assembly defined by any one of  claims 26  to  36 . 
     
     
         116 . A method of conducting a borehole surveying operation using a surveying instrument accommodated in an overshot assembly defined by any one of  claims 37  to  67 . 
     
     
         117 . A method of conducting a borehole surveying operation using a surveying instrument accommodated in an apparatus defined by  claim 68 . 
     
     
         118 . A method of conducting a borehole surveying operation using a surveying instrument accommodated in a drop tool assembly defined by any one of  claims 69  to  96 . 
     
     
         119 . A method of conducting a borehole surveying operation using a surveying instrument accommodated in an inner tube assembly forming part of a combination defined by any one of  claims 97  to  105 . 
     
     
         120 . A method of conducting a borehole surveying operation using a surveying instrument accommodated in a drop tool assembly forming part of a combination defined by any one of  claims 106  to  113 . 
     
     
         121 . A method of conducting a borehole surveying operation using apparatus incorporating an onboard downhole surveying instrument, the method comprising lowering the apparatus down the borehole, taking a measurement down the borehole using the onboard downhole surveying instrument, and retrieving a core sample using the apparatus. 
     
     
         122 . A method of conducting a borehole surveying operation using an inner tube assembly incorporating an onboard downhole surveying instrument, the method comprising deploying the inner tube assembly in the borehole, taking a measurement down the borehole using the onboard downhole surveying instrument, and retrieving the inner tube assembly containing a core sample. 
     
     
         123 . A method of conducting a borehole surveying operation using an overshot defined by any one of  claims 37  to  67 . 
     
     
         124 . A method of conducting a borehole surveying operation using an overshot assembly incorporating an onboard downhole surveying instrument, the method comprising lowering the overshot assembly down the borehole, taking a measurement down the borehole using the onboard downhole surveying instrument, and retrieving an inner tube assembly containing a core sample using the overshot assembly. 
     
     
         125 . A method of conducting a borehole surveying operation using a drop tool assembly incorporating an onboard downhole surveying instrument, the method comprising lowering the drop tool assembly down the borehole using the onboard downhole surveying instrument, and retrieving an inner tube assembly containing a core sample using the drop tool assembly and an overshot assembly.