Keeping the gas circulating is essential to prevent the growth of mud ring and reduce the tendency of pipe sticking.Д«ill Rehm. If the pipe is pulled up too hard it may stick tight. The important considerations are to not turn off the gas flow and to keep working the pipe. Tight-hole problems appear to be related to mud-ring problems or floating beds. A pilot test in a quart of injection water should be performed to give an indication of where to start the mist mixture. Fine or dissolved cuttings, oil, salts, and water hardness will all affect misting agents to some degree. A good starting point is 8 bbl/h of water. Enough misting agent needs to be added to see just a trace of foam at the blooie line. The quantity of foaming agent starts at 1% or 2% or about 1 or 2 quarts per bbl and is increased according to need. The mechanism is believed to be due to (1) lifting of cuttings away from the area of collar shoulder by foam and (2) soft mud ring with surfactants that is less restrictive to the movement of drill string. If gas injection rate cannot be increased due to limited capacity of compressor or borehole washout limitations, mud rings can be cut with foamer additions to the gas flow. A light mist often does not cut mud rings. The most effective means of reducing mud ring is to increase gas injection rate. Mud rings cause high friction which can result in downhole burn-offs (fire/explosion) in combustion condition and stuck pipe. This tends to form rings of mud that, as they grow larger, restrict gas flow and cause the pressure to increase. When the formation is damp from water or oil, the cuttings form a вЂњmudвЂќ that is deposited against the side of the hole. If the gas stream is not powerful enough to maintain the cuttings floating, significant amount of cuttings may accumulate in this area. Although the gas density is relatively high at this point compared to the upper-hole section, the kinetic energy of gas at this point is the lowest due to high pressure.

When drill cuttings move to the shoulder of drill collars, a floating bed of cuttings may form due to the low velocity of in situ gas in the pipe-open-hole annulus. The problem of вЂњ mud ringвЂќ is from inadequate hole cleaning. Na Wei, in Applied Gaseous Fluid Drilling Engineering, 2022 7.2.6 Cutting вЂњmud ringвЂќ

Plaster ring pipe