Analysis Of The Reasons For The Fracture Of The Drill Pipe Of The Drilling Rig

Abstract:  The drilling rig's fracture of the drill pipe is affected by geological aspects, such as reaming classification, drill...

  The drilling rig's fracture of the drill pipe is affected by geological aspects, such as reaming classification, drill pipe wear, and quality of the drill pipe. The following mainly introduces the reasons for the fracture from two aspects:

  The main causes of drill pipe fracture are:

  1. The bending moment of the drill pipe is too large during the process of reaming and pulling back the pipe;

  2. Reasons for excessive bending moment: First, the actual curve of the pilot hole deviates greatly from the theoretical curve; second, the hole is irregular after reaming, which makes the pipe form an included angle with the reamer and the axis of the drill pipe.

  other reasons:

  1. To save investment, the directional drilling equipment used by the construction contractor (that is, Party A) does not match the actual needs of the project construction. The tonnage of the directional drilling equipment is too small, the maintenance is not timely, and the failure rate is high, which makes the directional drilling force uneven, At the same time, stop-and-go construction leads to poor hole quality, irregular holes, and easy locking of drilling tools, resulting in drill pipe breakage;

  Second, the selection of the reamer model is unreasonable. Failure to select the matching model according to the actual geological conditions will increase the drilling torque, increase the wear and tear of the drill pipe and cause it to break;

  3. When the Drifter Bit is reaming or washing the hole, the drill pipe is not connected to the back, the reamer swings in the hole greatly, and the drill sticks, which will cause the drill pipe and the main shaft of the reamer to break;

  4. The selection of drill pipes is unreasonable. Because the drill pipes are not tracked and managed, and the statistics of drill pipe inspection data are lacking, the service life of a set of drill pipes used is uneven, and the drill pipes with greater wear and tear are broken due to stress concentration;

  5. The deviation control of the pilot hole is unreasonable, and the deviation is too large. In the later correction process, due to the inflexible actual curve, the bending moment borne by the drill pipe is too large, which may easily lead to an increase in the stress of the drill pipe or directly cause the surface of the drill pipe to suffer from excessive friction. Fracture, especially the high deflection friction force of the drill pipe joint, which causes a large amount of heat to be generated during periodic contact and friction with the hole wall, causing the surface material of the joint to undergo periodic heating and cooling, making the surface brittle. Under the simultaneous influence of significant factors, the longitudinal cracking of the inner thread of the drill pipe joint is caused;

  6. The reaming classification is unreasonable. The construction unit reduces the reaming classification to catch up with the construction period, which greatly increases the drilling torque, which may easily lead to increased wear and fracture of the drill pipe;

  7. Due to the unsatisfactory geological conditions, the channel is broken and collapsed, and there are too many cuttings, the anti-locking ability of the drilling tool is low, and the risk of locking increases, resulting in the breakage of the drill pipe.

  The above is the reason for the fracture of the drill pipe of the drilling rig. When selecting the rod, it should be strictly managed and matched with the model parameters of the drilling rig.