Prevention of mud caking on PDC drill bits

I. Adjustment of mud properties before PDC drill bit entry

PDC (polycrystalline diamond compact) drill bits are a type of drill bit used in the oil and gas industry to drill through hard rock formations. These drill bits are made with a layer of synthetic diamond particles that are fused together under high pressure and temperature, making them extremely durable and long-lasting. PDC drill bits are known for their high drilling efficiency, low maintenance requirements, and reduced drilling costs. We offer types of PDC drill bits including matrix body PDC drill bit.

  1. Mix oil or increase the amount of lubricant to prevent drill cuttings from adhering to the drill bit.

  2. Increase the polymer content in the drilling fluid to control fluid loss and improve mud cake quality.

  3. Improve the inhibitory properties of the drilling fluid to reduce the hydration dispersion of shale.

  4. Reduce the viscosity and shear force of the drilling fluid and promptly remove poor-quality solid phase.

  5. For high-permeability sand layers, the shield and temporary plugging technique can be used to reduce permeability loss.

  6. For clay-bearing formations, alkali should be added in advance to prevent contamination of the mud.

  7. Maintaining and treating the mud properties is effective in preventing mud caking on PDC drill bits before and after entry into the well. Before pumping, a certain amount of cleaning agent (surfactant) can be added to clean the drill bit, which also has a certain effect.There are also types of drill bits in oil and gas.

II. Engineering measures for petroleum drilling equipment

Similar to steel tooth tricone bit, using PDC drill bit you need to pay attention to:

  1. First, select the PDC drill bit with a design that facilitates chip removal, such as the size of the waterway.

  2. Before inserting the PDC drill bit, fully circulate the mud and clean the wellbore to prevent the drill cuttings remaining in the wellbore from continuing to hydrate and disperse.

  3. Before inserting the PDC drill bit, conduct short reaming to scrape and compress the mud cake on the wellbore wall, thinning and compacting it to ensure smooth wellbore and eliminate obstructions. If all methods fail to prevent mud caking on PDC drill bits in the high-risk area, using a mill-tooth bit to pass through the well is necessary.

  4. During drilling, coat the surface of the drill bit's waterway with butter to form a protective film, reducing the contact time between the drill bit and poor-quality solid phase in the mud. Alternatively, wrap the drill bit to protect it, which can be effective even in deep wells.

  5. During drilling, the drill bit continuously scrapes the wellbore wall, and the mud cake on the wellbore or drill cuttings remaining in the well will accumulate on the drill bit. It is necessary to circulate the mud and flush the PDC drill bit clean during drilling.

  6. During drilling, the speed should be controlled appropriately to prevent the drill bit from suddenly entering a sand bridge or drilling into a pile of rotten mud. Moreover, if the speed is appropriate, the PDC drill bit will move along the spiral wellbore track drilled by the previous drill bit instead of scraping off a large amount of mud cake on the wellbore wall.

  7. Every time the drill reaches the bottom, the pump should be turned on first, and the displacement should be increased as much as possible to flush the bottom of the well and the drill bit. After the displacement meets the requirements, rotate the drill bit slightly and drill 0.5-1m, which is also a requirement of the PDC drill bit design. 

  8. Use a large displacement drilling as much as possible to ensure the sufficient cleaning and cooling of the PDC drill bit. 

  9. When drilling in soft mudstone, low drilling pressure, high speed, and large displacement should be used as much as possible. There is no need to blindly pursue a slightly higher drilling speed with high drilling pressure, which is only the way to use a mill-tooth bit.

  10. The operation should be delicate, and the pressure of sending the drill should be uniform and not sporadic.

You may also be interested in tricone bits, PDC cutters, PDC reamers, etc. Contact us for more help.