Apparatus and method for directional drilling with coiled tubing

Apparatus for directional drilling with coiled tubing comprising:

• an uphole sub connected to the coiled tubing;
• a downhole sub having a bent housing and a drill bit, rotation of the drill bit forming a borehole;
• a rotary connection between the uphole sub and the downhole sub for enabling rotation therebetween;
• and
• a clutch positioned between the rotary connection and the uphole sub and operable between engaged and disengaged positions using fluid cycles applied alternately to engage the clutch and to disengage the clutch, a fluid cycle comprising a substantial change in pressure of the drilling fluid, so that when the clutch is disengaged, the bent housing is locked against rotation and when the clutch is engaged, the bent housing is rotatable.
• a speed reducer between the rotary connection and the uphole sub and having a low speed output connected to the rotary connection;
• a first motor mounted in the downhole sub and which rotates the drill bit, reactive torque from the drill bit being transmitted into the downhole sub so that when the clutch is engaged, the reactive torque causes the downhole sub and bent housing to rotate opposite to the drill bit and the speed reducer dissipates torque so as to retard free rotation of the downhole sub;
• and
• means driven by a high speed input for dissipating torque at the speed reducer.

Apparatus for directional drilling with coiled tubing comprising:

• an uphole sub connected to the coiled tubing;
• a downhole sub having a bent housing and a drill bit, rotation of the drill bit forming a borehole;
• a rotary connection between the uphole sub and the downhold sub for enabling rotation therebetween;
• a clutch positioned between the rotary connection and the uphole sub and operable between engaged and disengaged positions using fluid cycles applied alternately to engage the clutch and to disengage the clutch, a fluid cycle comprising a substantial change in pressure of the drilling fluid;
• a speed reducer between the rotary connection and the uphole sub and having a low speed output connected to the rotary connection;
• a first motor mounted in the downhole sub and which rotates the drill bit, reactive torque from the drill bit being transmitted into the downhole sub so that when the clutch is engaged, the reactive torque causes the downhole sub and bent housing to rotate opposite to the drill bit and the speed reducer dissipates torque so as to retard free rotation of the downhole sub.
• wherein the clutch further comprises:
• an input shaft and co-rotating first clutch face;
• an output shaft and co-rotating second clutch face formed on a collar which reciprocates axially thereon, the output shaft being connected for co-rotation with the lower sub;
• a third clutch face formed on the collar;
• and
• a fourth clutch face formed on the uphole sub
• an axially reciprocating mandrel, one end of which alternately engages and disengages the collar;
• a piston for reciprocating the mandrel in response to pressure changes in the drilling fluid;
• and
• a barrel cam formed on the mandrel which indexes the mandrel between its first and second position so that
• i. when the clutch is disengaged, the collar is reciprocated axially to a first position to disengage the first and second clutch faces and lock the bent housing against rotation and engage the third and fourth clutch faces for locking rotation between the output shaft and the uphole sub, and
• ii. when the clutch is engaged, the collar is reciprocated axially to a second position to engage the first and second clutch faces so as permit the bent housing to rotate for co-rotating the downhole sub and disengage the third and fourth clutch faces.

Apparatus for directional drilling with coiled tubing comprising:

• an uphole sub connected to the coiled tubing;
• a downhole sub having a bent housing and a drill bit, rotation of the drill bit forming a borehole;
• a rotary connection between the uphole sub and the downhole sub for enabling continuous rotation;
• a clutch positioned between the rotary connection and the uphole sub for alternately locking the bent housing against rotation and freeing the bent housing for rotation;
• a speed reducer positioned between the coiled tubing and the bent housing and having a high speed shaft and a low speed shaft, the low speed shaft being connected to the bent housing so that when the bent housing is free for rotation, reactive torque from the rotary drill bit causes the bent housing to contra-rotate at a speed less than that of the rotary drill bit;
• and
• means driven by the high speed shaft for dissipating torque at the speed reducer.

A method for directional drilling in a borehole with coiled tubing having a bent housing and rotary drill bit connected thereto, the method comprising:

• providing a speed reducer having a low speed output connected to an upper end of a clutch and a rotary connection between a lower end of the clutch and the bent housing, the clutch operable between engaged and disengaged positions through cycling of drilling fluid flow through the coiled tubing;
• orienting the bent sub by
• engaging the clutch for coupling of the speed reducer to the rotating connection,
• orienting the bent sub in the borehole by rotating the drill bit, reactive torque causing bent sub and rotating connection to contra-rotate and drive the speed reducer through the clutch;
• drilling a borehole in a sliding operation by disengaging the clutch for decoupling the speed reducer from the rotating connection and for locking the rotating connection to the coiled tubing, then drilling with the drill bit;
• drilling a borehole in a rotating operation by engaging the clutch for coupling of the speed reducer to the rotating connection and releasing the rotating connection from the coiled tubing, then drilling with the drill bit wherein reactive torque causes the bent sub and rotating connection to contra-rotate simultaneously;
• and
• dissipating torque at the speed reducer by driving an energy dissipating device.

A method for directional drilling in a borehole with coiled tubing having a bent housing and rotary drill bit connected thereto, the method comprising:

• in a sliding operation, orienting a bent housing by engaging a clutch to couple the bent housing through a rotary connection at the coiled tubing to a speed reducer, drilling with the rotary bit wherein reactive torque causes the bent sub to contra-rotate at the rotary connection, and once oriented, disengaging the clutch for disengaging the speed reducer and for locking the bent housing against relative rotation to the coiled tubing, and drilling with the rotary bit;
• in a rotating operation, engaging the clutch to unlock the bent housing from the coiled tubing and for coupling the bent housing to the speed reducer, and then drilling with the rotary drill bit wherein reactive torque causes the bent sub to contra-rotate;
• and
• dissipating torque at the speed reducer by driving an energy dissipating device.

A method of directional drilling with coiled tubing comprising the steps of:

• providing a bottom hole assembly at a down hole end of the non-rotating coiled tubing, the bottom hole, assembly comprising an uphole sub having a clutch and a rotating connection, and a downhole sub connected to the upper sub's rotating connection, the downhole sub having a bent housing and a rotary drill bit;
• orienting the bent housing by engaging the clutch for unlocking the rotating connection for coupling a motor and a speed reducer with the downhole sub for rotation of the downhole sub to the desired orientation;
• performing sliding drilling operation by disengaging the clutch for locking the rotating connection and drilling a curved borehole with the rotary bit;
• performing rotating drilling operation by engaging the clutch for unlocking the rotating connection for rotation of the downhole sub drilling with the rotary bit while the downhole sub rotates at the rotating connection for drilling a substantially straight borehole;
• and
• dissipating torque at the speed reducer by driving an energy dissipating device.