Method of continuously raising and lowering oilfield saft drillstring and twin travelling slips apparatus

Abstract

Disclosed is a method of continuously raising and lowering an oilfield shaft drillstring using a double traveling slips device, wherein two sets of traveling slip mechanism form the two traveling slip mechanisms to form the two traveling slips device, the first set of traveling slip mechanisms and the second set of traveling mechanisms are respectively mounted on a pithead apparatus ( 10 ) to constitute a continuous raising and lowering system. In the process of raising and lowering an oilshaft drill-string, the slips ( 1, 4 ) of each set of traveling slip mechanisms alternately clamp or release the drillstring, ensuring a continuous raising and lowering motion for the drillstring ( 9 ) from beginning to end under the clamping of the slips, and achieving uninterrupted operation. Further disclosed is a double traveling slips device.

What is claimed is: 
     
         1 . A method for continuously raising and lowering an oilfield shaft drillstring comprising steps of:
 forming a double traveling slips device by a first set of traveling slip mechanism and a second set traveling mechanism, respectively providing a first set of traveling slip mechanism and a second set traveling mechanism on a wellhead equipment to form the double traveling slips device which is a continuous raising and lowering system;   wherein in a process of raising and lowering the oil shaft drillstring, the slips of each set of traveling slip mechanisms alternately clamp or release the drillstring, so as to ensure a continuous raising and lowering motion for the drillstring from beginning to end under clamping of slips, and achieve uninterrupted operation.   
     
     
         2 . A double traveling slip device comprising a first set of traveling ship mechanism and a second set of traveling ship mechanism;
 wherein the first set of traveling ship mechanism comprises a first slip, a first upper crossbeam, two first slip-lifting hydraulic cylinders and a first lower support beam, wherein the first slip is provided on the first upper crossbeam; the first upper crossbeam is connected with piston rods of the two first slip-lifting hydraulic cylinders to form a first gate-shaped lifting mechanism;   the two first slip-lifting hydraulic cylinders are fixed on a pup joint of a wellhead equipment via the first lower support beam;   the other set of traveling slip mechanism comprises a second slip, a second upper crossbeam, two second slip-lifting hydraulic cylinders and a second lower support beam; wherein the second slip is provided on the second upper crossbeam; the second upper crossbeam is connected with piston rods of the two second slip-lifting hydraulic cylinders to form a second gate-shaped lifting mechanism, the two second slip-lifting hydraulic cylinders are fixed on the pup joint of a wellhead equipment via the second lower support beam.   
     
     
         3 . The double traveling slip device, as recited in  claim 2 , wherein the first set of traveling slip mechanism and the second set traveling slip mechanism constitute a gate-shaped frame crossing in space to form a square shaped structure, or the two first slip-lifting hydraulic cylinders of the first set of traveling slip mechanism are on an lateral of the second slip-lifting hydraulic cylinder of the second set of traveling slip mechanism;
 the first set of traveling slip mechanism and the second set of traveling slip mechanism are both connected with a pup joint of a wellhead equipment, so as to form stereo structure with paralleling gate shaped frames having central axis an identical plane the parallel rectangles by sharing the same central axis; the pipe penetrates a center of an internal hole of the first slip and a center of an internal hole of the second slip and then is inserted into the wellhead equipment.   
     
     
         4 . The double traveling slip device, as recited in  claim 3 , wherein internal holes of both the first slip and the second slip are closed geometry shapes comprising an internal cylinder, an internal cone, an internal prism and a pyramid. 
     
     
         5 . The double traveling slip device, as recited in  claim 2 , wherein a first gate-shaped frame of the first set of traveling slips mechanism and a second gate-shaped frame of the second set of traveling slips mechanism are parallel on each side of the gates and form a cuboid. 
     
     
         6 . The double traveling slip device, as recited in  claim 3 , wherein one side of the internal holes of both the first slip and the second slip are an open-mouth shape on one end, and a width of the open-mouth end is greater than a diameter of the drillstring.