How to Operate the Tricone Bit after Descending into the Well?

Operation analysis of tricone bit after going down well:

(1) When drilling down and encountering an obstructive stroke, the drilling pressure should be controlled below 20KN, and the speed should be less than 50 rpm. Large section reaming and non-circulating drilling fluid reaming are strictly prohibited.

(2) The tricone drill bit should be straightened and slowed down when entering the well, and find the middle position when it reaches the plugging device. When passing through the choke ring position, especially slow down the lowering speed and pay attention to avoid collision.

(3) The bottom of the well is shaped. When drilling with an ordinary rotary table, carefully transport the roller cone bit. After confirming that the bit contacts the bottom hole, run in the bottom hole with a speed of about 50 rpm and a WOB of 5-10kn. The footage is 0.5m-1m7. A short trip should be conducted every 300-400M to prevent the piston from pulling out.

(4) When the tricone bit is used in the later period, the wear of the cutting teeth is increased, which reduces the depth of the cutting teeth into the formation, so the weight on bit can be appropriately increased to maintain a high drilling speed.

(5) When drilling down to the bottom of the well, start the pump in advance. If the drill bit is more than 0.5 meters away from the bottom of the well, slowly move up and down and rotate the drilling tool to fully circulate the drilling fluid. After the bottom of the well is cleaned, correct the indicator weight. The bottom of the well can be shaped after the pump pressure is normal.

Some other notes for operating the tricone bit

When directional drilling with tricone drill bit, check whether the power drill is operating normally. A test run should be performed when the drill is not connected. It is strictly forbidden to connect the drill bit to the wellhead for trial operation to prevent damage to the cutting teeth; If there is no footage in the bit, the pump pressure increases or decreases obviously, the ROP decreases suddenly, and the torque increases, trip out inspection shall be conducted if there is no problem with the surface equipment. When the drill bit is taken out of the box, a wooden board or a rubber pad should be placed under it. When loading and unloading the drill bit, use a bit loader and tighten the bit according to the recommended torque of the corresponding thread size.

Before the tricone rock bit enters the well: a fishing cup is installed on one drill bit, after the previous one is lifted out, the cone bit enters the well. Check the wear of the outer diameter and other wear conditions. If the outer diameter is measured, the diamond bit can be used in the well. Check whether the cutting teeth are damaged; check whether the water eye is blocked; check the outer diameter of the drill bit; check whether the drilling fluid meets the design requirements; check whether the purification equipment is operating normally. It is recommended to use a desander. When the drill bit is in contact with the bottom of the well at low pressure, and the downhole power drilling tool is used for drilling, the drill bit should start the pump when it is close to the bottom of the well and gradually increase to the required displacement; After cleaning the bottom of the well for a short time, slowly increase the WOB; When the weight on bit increases, the pump pressure also rises accordingly. The change in pressure and the value of the weight on bit must be controlled within the technical specifications of the recommended motor; The drill rod should be rotated slowly to prevent sticking; others are operated according to the standard operation of ordinary rotary table drilling. Tricone bits are not suitable for drilling gravel layers; Before drilling in gravel layer, pull out in advance and run the cone bit. After passing through gravel layer, run the diamond bit; When drilling in large loose sandstone formation, ROP should be appropriately reduced to consolidate the open hole wall and prevent casing from being blocked.