Steerable Gas Turbodrill

Abstract

A gas turbodrill with an adjustable bent housing for use in a spur lateral drilling application. The gas turbodrill includes a high-speed gas turbine, a gearbox assembly, a pivoting shaft connection point, a gimbal assembly comprising a hollow ball and socket joint, a bearing assembly and drill bit assembly. The gas turbodrill gimbal assembly enabling a bend through an angle of up to 5 degrees while drilling. Springs and the application of pressure will lock the bend in place once drilling commences to facilitate lateral drilling of the spur.

1 . A gas turbodrill system including a gas turbodrill assembly, the gas turbodrill assembly comprising:
 a gas turbine assembly configured to couple to a source of pressurized fluid and comprising a drive shaft;   a gearbox assembly configured to couple to the drive shaft of the gas turbine and comprising an output shaft, the gearbox assembly being configured to rotate the output shaft at a lower rate than the drive shaft of the gas turbine;   a gimbal assembly that comprises a hollow ball and socket joint that extends around a flexible shaft, the flexible shaft configured to couple to the output shaft of the gearbox assembly, the flexible shaft extending through the hollow ball and socket joint; and   a drill-bit assembly connected to the gimbal assembly, the drill-bit assembly having a shaft connected to the flexible shaft.   
     
     
         2 . The gimbal assembly of  claim 1 , further comprising at least one spring that presses a lock ring with a spherical seat against the ball of the ball and socket joint, the lock ring positioned to lock the position of the ball and socket joint when a pre-determined force is applied and configured to retain the locked position of the ball and socket joint when force is removed. 
     
     
         3 . The gas turbodrill assembly of  claim 1 , further comprising a preloaded spring section in the gimbal assembly that presses against the ball and socket joint and is positioned to press against the ball and socket joint when a force is applied and assist in retaining the position of the ball and socket joint when the force is removed 
     
     
         4 . The gas turbodrill assembly of  claim 1 , further comprising a clamp coupling assembly enclosing the connection of the gearbox assembly output shaft and the flexible gimbal assembly shaft. 
     
     
         5 . The gas turbodrill assembly of  claim 1 , further comprising a spring support section in the gimbal assembly positioned to tension against the flexible gimbal assembly shaft. 
     
     
         6 . The gas turbodrill assembly of  claim 1 , further comprising a drill-bit assembly having one or more fixed cutters. 
     
     
         7 . The gas turbodrill system of  claim 1 , further comprising a drill-bit assembly having a plurality of surface set diamond bits. 
     
     
         8 . The gearbox assembly of  claim 1 , further comprising a planetary gear transmission. 
     
     
         9 . The gas turbodrill system of  claim 1 , further comprising:
 a whipstock positioned to guide the gas turbodrill assembly on a lateral exit path, the whipstock having a ramp connected to a spring, the ramp and spring positioned to exert force against the gas turbodrill assembly at a pinch point near an upper end of the whipstock, thereby providing additional force to rotate the ball and socket joint of the gimbal assembly and bend the flexible shaft.   
     
     
         10 . A gas turbodrill system including a gas turbodrill assembly, the gas turbodrill assembly comprising:
 a gas turbine assembly configured to couple to a source of pressurized fluid;   a gimbal assembly that comprises a hollow ball and socket joint that extends around a flexible shaft, the flexible shaft configured to couple to the output shaft of the gas turbine, the flexible shaft extending through the hollow ball and socket joint;   a gearbox assembly configured to couple to the flexible shaft, the gearbox assembly having an output shaft, the gearbox assembly being configured to rotate the output shaft at a lower rate than the flexible shaft; and   a drill-bit assembly connected to the gearbox assembly, the drill-bit assembly having a shaft connected to the gearbox assembly output shaft.   
     
     
         11 . The gas turbodrill assembly of  claim 10 , further comprising a clamp coupling assembly enclosing the connection of the gas turbine output shaft and the flexible shaft. 
     
     
         12 . The gimbal assembly of  claim 10 , further comprising at least one spring that presses a lock ring with a spherical seat against the ball of the ball and socket joint, the lock ring positioned to lock the position of the ball and socket joint when a pre-determined force is applied and configured to retain the locked position of the ball and socket joint when force is removed 
     
     
         13 . The gas turbodrill assembly of  claim 10 , further comprising a preloaded spring section in the gimbal assembly that presses against the ball and socket joint and is positioned to press against the ball and socket joint when a force is applied and assist in retaining the position of the ball and socket joint when the force is removed. 
     
     
         14 . The gas turbodrill assembly of  claim 10 , further comprising a drill-bit assembly having one or more fixed cutters. 
     
     
         15 . The gas turbodrill assembly of  claim 10 , further comprising a drill-bit assembly having a plurality of surface set diamond cutters. 
     
     
         16 . The gearbox assembly of  claim 10 , further comprising a planetary gear transmission. 
     
     
         17 . The gas turbodrill system of  claim 10 , further comprising:
 a whipstock positioned to guide the gas turbodrill assembly on a lateral exit path, the whipstock having a ramp connected to a spring, the ramp and spring positioned to exert force against the gas turbodrill assembly at a pinch point near an upper end of the whipstock, thereby providing additional force to rotate the ball and socket joint of the gimbal assembly and bend the flexible shaft.   
     
     
         18 . A method of drilling a spur lateral well with a gas turbodrill assembly, comprising the steps of:
 running a whipstock into the well;   positioning the whipstock lateral exit path using a wireline;   running a steerable gas turbodrill assembly into the well until it reaches the whipstock;   applying force downwardly on the steerable gas turbodrill causing the gas turbodrill to press against the whipstock, thereby rotating a ball and socket joint and bending a flexible shaft housed in a gimbal assembly of the steerable gas turbodrill.   
     
     
         19 . The method of drilling a spur lateral well as described in  claim 18 , further comprising the step of:
 applying force downwardly on the steerable gas turbodrill with sufficient force to cause the gimbal assembly flexible shaft to bend and substantially lock in place.   
     
     
         20 . The method of drilling a spur lateral well as described in  claim 18 , further comprising the steps of:
 applying force downwardly on the steerable gas turbodrill causing a ramp and spring of the whipstock to exert force against the gas turbodrill assembly near a pinch point on an upper end of the whipstock, thereby providing additional force to rotate the ball and socket joint of the gimbal assembly and bend the flexible shaft.