Drilling Fluid: The "gunk plug" The "gunk plug" is an adaptation of the gunk squeeze method used to plug fractures. The gunk plug forms when water comes in contact with bentonite that has been placed in the hole as a concentrated suspension in diesel oil. Water causes the bentonite to swell to form a putty-like mass. When the gunk plug is placed through the drill pipe, care must be taken to have enough diesel oil precede and follow the bentonite suspension to serve as a barrier to prevent any mixing with water before the suspension has been displaced from the pipe. There are several types of "Gunk Squeeze". Typically a mixture of 300-400 ppb of bentonite in diesel or synthetic oil is pumped . The bentonite affinity for water causes rapid thickening (or hardening) that can seal of a loss zone. A 50:50 mixture of bentonite/oil and mud can plug open holes because it gives near instantaneous setting. The one draw back to this method of curing losses is that you are to be pretty sure that you know exactly what part of the hole the loss zone is in. BENTONITE-DIESEL/SYNTHETIC OIL (10 bbls at 11.3 ppg) 7.2 bbl diesel/synthetic oil 2600 lbs bentonite 50 lbs course mica 50 lbs fine mica 10 lbs fiber Can be mixed a weighted with barite. BENTONITE-CEMENT-DIESEL/SYNTHETIC OIL (10 bbls at 11.7 ppg) 7.1 bbl diesel/synthetic oil 1400 lbs bentonite 1300 lbs cement Add LCM material as required, and barite to attain required weight. Invert BDO/BSO formulations mix with oil (or OBM) and react the same way that normal "gunk squeezes" do in WBM. INVERT BENTONITE-DIESEL/SYNTHETIC OIL (Water Organophilic Bentonite) *10 bbls at 12.0 ppg 7.14 bbl drill water 33 lbs lignosulfonate 16.5 lbs caustic soda 2500 lbs organophilic clay (VG-69, GELTONE V etc.) *10 bbls at 16.4 ppg 5.9 bbl drill-water 10 lbs caustic soda 5 lbs lignosulfonate 1625 lbs organophilic clay 3000 lbs barite TIPS 1. Make sure mixing pit, hopper, lines, etc, are completely clean 2. Isolate pop-offs and use cementing lines 3. Spacers of at least 10 bbl diesel/synthetic oil before and after the "gunk pill" to prevent plugging in the pipe (or water/gel pills when using OBM) 4. Squeeze pills into loss zone from 50ft above (at 1-4 bpm) 5. Once final squeeze pressure is obtained, pull into casing shoe with drill pipe and hold pressure for 2-4 hours. If cement is used, allow another 8 hours before attempting to drill Drilling with slight lose or minimum is quite common but in this writers opinion is an extremely dangerous practice even in so called known fields. However it is done and here is how. The annular pressure loss it +/- 6% of the total system pressure lost and is added to the Bottom hole pressure if this is reduce it may be possible to bring down the lose of fluid "It can be live with" comes to mind.   Lets say the system pressure loss is 3000 psi 6% of that would be 180 psi +/- By slowing down the flow rate you will lower the circulating pressure and the pressure lose in the annuals. This will not cure the loss just relieve some of the pressure  Cement can also be used to cure and plug lost zone. In know loss area drilling with no jet will allow cementing through the bit. This is not a common practice but there are times when it may be the only way. This system will often be used in conjunction with well control problem. Straddle packer are another way of using cement. A lot of time and money has been spent on developing a drillable straddle packer. The idea behind such packers is to isolating the section of well bore near a loss zone in order to improve the efficiency of the cementing operation. The packer off consists of two packer one above and one below the loss zone, thereby directing cement into the well bore region between the two bags and forcing most of the cement into the loss zone. More recently such packed have been developed that are made of flexible materials that inflates with cement using the differential pressure that develops across the cement ejection ports in the packer assembly making them a lot easier to drill out. Another unconventional mud approach is the use of mud caps. In these applications, the annulus is shut in and the wells are drilled without returns. Water is pumped down the drill pipe and is lost to the natural fracture system along with the cuttings. Mud on the annulus provides pressure control. Applications for mud caps include very low-pressure formations with severe lost circulation potential and very high-pressure intervals. They have been widely used in applications where both high and low-pressure fractures may be encountered. There is still a long way to go with this page, attached to this page is a discussion group The idea is quite simple I often find when I read what others have written it jolts my memory It could do the same for you. However instead off letting things slide just pop a note on the board We can then transfer it into this page Acknowledgement:  Alan Rodgerson Consultant mud engineer for his help and information on formulating the gunk