Efficient and effective drilling operations require meticulous attention to detail and adherence to best practices. Whether drilling in cased hole or open hole environments, encountering tight spots, or maximizing the performance of PDC drill bits, understanding key guidelines is essential for success. This comprehensive guide delves into essential recommendations for optimizing drilling operations, covering various topics from hole entry to overcoming deviation problems.
Running in the hole
- In cased hole, take care when entering conductor pipe or lines and when passing through drilled out cementing equipment.
- In open hole, take care with suspected or known tight spots, ledges, doglegs or keyseats. Be especially cautious with increased BHA stiffness because a roller cone bit has some “give” that pdc drill bits do not have.
- When washing to bottom, follow this recommendation for the last two joints of open hole: rotate at 40-60 RPM with a maximum of about 3K WOB. This will ensure the absence of an under-gaged hole AND drill any fill that may be present. After tagging bottom, pick up off bottom and pump at full flow rate for about 5 minutes.
- Perform conventional drill-off tests to identify optimum running parameters.
Indications of Unstable Bit Rotation
- Large WOB fluctuations.
- Increased surface torque fluctuation or cycling torque.
- If ROP drops below 20 fph, the formation has a hard stringer or a bit is running unstable.
- Check this guide if you are experiencing any downhole vibration.
Reaming
- Use a roller cone to ream a hole – not a PDC.
- For extensive reaming, do not run a PDC bit.
- Use extreme caution and follow this guideline when encountering tight spots: rotate at 60 RPM with no more than 3K WOB.
Rule of Thumb to Improve PDC Drill Bit Performance To Reduce PDC Cutter Damage
- Use the automatic driller to place the bit in contact with the hole bottom. A hard impact with the hole bottom will damage PDC cutters and shorten the bit’s life.
- Maximize flow rates at all times. Frictional heat due to lack of cooling/cleaning can lead to increased PDC cutter and blade damage.
PDC Bit Hydraulics
- Good PDC hydraulics include maximizing flow rates BEFORE maximizing HSI (hydraulic horsepower per square inch).
- Use relatively small nozzle sizes if the rig has enough pump to allow for both maximized flow rates and optimized HSI. When using LCM, run large enough nozzles to allow the LCM to pass through.
- Always try to run similar size jet nozzles in a PDC drill bit. Jet nozzles that vary greatly in size can allow cuttings to enter the bigger jet nozzle when the pump turns off. Then, the cuttings will plug the smaller jet nozzles when the pumps turn back on.
Maximizing ROP
- Keep WOB to a minimum in the upper section of the production hole. Excessive WOB can lead to early wear flat on cutters, possibly leading to bit balling and deviation. When ROP slows, try backing off WOB to 8-13k to let the hole clean up, then gradually increase WOB in small increments to the desired ROP. Note: Adding weight is not always the answer to slow ROP. Along with backing off weight, try slowing the rotary some; this can help the bit get back in the bottom hole pattern and allow it to take the “bite” it needs.
Deviation Problems
With a BHA
To help reduce hole angle, at the bottom of each kelly down, latch the brake handle and allow the bit weight to drill itself off.
After making the new connection, back ream the last 30 feet to the bottom before drilling more footage.
Deviation Problems
Without a BHA
Increase RPM and decrease bit weight.
Conclusion
Optimizing drilling operations involves a combination of knowledge, skill, and attention to detail. By following the guidelines outlined in this comprehensive guide, drilling professionals can enhance efficiency, minimize downtime, and achieve optimal results. From exercising caution during hole entry to maximizing PDC drill bit performance and addressing deviation problems, incorporating these best practices into drilling operations can lead to smoother, safer, and more productive drilling endeavors.
