Key points for preventing stuck pipe when using rock drilling bits
Strictly control weight on bit (WOB). Generally keep WOB ≤ 50 kN. During certain directional‑well operations WOB may be permitted up to 100 kN for short periods, but normal drilling of vertical and directional sections should adhere to ≤ 50 kN. Refine parameters according to actual wellbore conditions.
For surface drilling ensure sufficient circulation displacement so cuttings are fully conveyed and removed. Make short trips (up/down) promptly to keep the hole clean. Before drilling, pump a pre‑hydrated viscosified mud with a Marsh‑funnel viscosity around 50–60 s (adjust by hole size and depth) to suspend residual cuttings in the wellbore and prevent cuttings from sticking to the bit.
Before making up a single drill‑pipe joint, observe additional axial load on the drillstring. If signs of pack‑off or blockage appear, do not force the connection; first circulate thoroughly and adjust mud properties before proceeding.
Enforce strict mud purification standards. Keep the solids‑control system operating effectively—use fine‑mesh shakers and high‑performance centrifuges—to control sand content below 0.5% and remove harmful solid particles.
Maintain appropriate pump discharge volumes:
444.5 mm hole: > 60 L/s
311.1 mm hole: 55–60 L/s
241.3 mm hole: 35–40 L/s
215.9 mm hole: 28–32 L/s
In intervals where mixing oil is permitted, control drilling‑fluid oil content at 5–8% to improve lubrication and reduce the risk of sticky‑hole problems.
After completing drilling with a single bit run, perform 1–2 full circulations immediately, with adequate flow, to ensure cuttings return from the bit face and prevent cuttings settling that can cause the bit or stabilizer to stick.
For multi‑point testing operations, confirm downhole conditions (suspended weight, circulating pump pressure, etc.) are normal before starting tests.
If excessive torque, high make/break friction, or sticky connections occur during drilling, add polymeric beads (plastic balls), extreme‑pressure lubricants, or similar agents to improve lubrication and prevent sticking.
When directional drilling proceeds slowly, periodically move the drillstring to avoid long static intervals that promote sticking. If pack‑off occurs, inject lubricant and use short‑stroke reciprocation to clear the hole and improve borehole wall lubrication.
Before drilling open‑hole sections circulate the mud thoroughly and start at low speed/low torque. If suction or pack‑off is encountered, when making connections with top‑drive/square tubulars consider pumping slurry/grout through the top drive or perform backreaming; never forcefully apply additional drilling pressure to advance.
In deviated intervals and keyseat locations pass slowly at low speed and frequently reciprocate the drillstring. For minor sticking, limit WOB to ≤ 50 kN and attempt light downward weight with slow rotation to free the tool. Intermittent pulsed water jetting can be used to break keyseats.
Do not allow the bit to remain stationary in open hole for more than 5 minutes. During circulations, equipment maintenance, or other stoppages, keep the drillstring active to prevent sticky‑hole conditions.
