|Lost Circulation Materials|
Lost Circulation occurs when there is a continuous loss of whole mud into permeable formations, fractures or voids. To cure the loss of whole mud the zones must be plugged so that a filter cake can be formed. In diamond drilling the loss of returns above the water table may result in a dry hole which can cause problems when landing the core barrel inner tube. Lost circulation materials may be divided into fibres, flakes and granules. In general, fibres and flakes are more effective in low density muds and are more applicable to diamond drilling and water well drilling. Care should be taken when drilling into aquifers using loss circulation materials to avoid plugging of the aquifer and subsequent bore development problems. AMC has a range of lost circulation products which are designed to cover most drilling applications.
AMC AUS-PLUG - is a hydrophilic polymer in granular form that absorbs up to 500 times its original volume in water. AUS-PLUG is ideal for sealing zones of lost circulation and can also be used to reduce rod vibration in holes where lost returns are a problem. AUS-PLUG should be mixed with fresh water then pumped down the hole to the zone of lost circulation. The mixture will then swell and seal fissures, cracks and porous formations. Drilling can recommence after a waiting period of 30 minutes. In diamond drilling, to avoid long delays while waiting for AUS-PLUG to swell down-hole, the AUS-PLUG can be pre-wetted with water in a 20-40 litre container. Once the tube has been pulled, this solution can be poured directly down the rods. After pumping the tube down the rods drilling can recommence. This procedure can be repeated on successive core runs. In circumstances where a low water level or total loss of water returns results in excessive vibration and torque, AUS-PLUG can be allowed to swell in water or mud for 15-20 minutes. The resulting swollen mixture can be periodically poured down the outside or the rods and acts as a cushion between the rod string and hole casing. AMC AUS-PLUG is packaged in 8kg Pails. Usage is 0.5kg to 1.5kg per 1000ltrs.
AMC KWIK-SEAL - is an engineered blend of granular, flake, and fibrous materials. It is available in three grinds to function effectively over the widest range of lost circulation materials. KWIKSEAL’S primary function is to stop lost circulation in a wide range of conditions with water based drilling fluids. Coarse grind is used to seal large fractures and highly permeable formations and can be pumped easily through large jets or open pipe. Medium grind is extremely effective in sealing medium to fine fractures and porous zones and can be used with most jet bits. Fine grind is where seepage losses are a problem, such as with fine fractures or porous formations. Fine will circulate through coarse mesh shaker screens (+ - 20 mesh) and can be maintained in the mud as a filler. It is recommended that Medium grind be used for diamond drilling applications when 100% lost circulation is encountered. The tolerances experienced in diamond drilling are too small for the coarse grind to be used. Specific blend of high strength granules (bridging agents), fibres (matting agents), and flakes (sealing agents), It functions by first forming a bridge, then packing off around the bridge to create a seal. Tight, strong, seal under high and low pressure differentials, Can be used to effectively stop loss of fluid in unconsolidated formation and fractures. The seal is not easily removed by bit movement or mud circulation, Effective in small quantities. AMC KWIK-SEAL is packaged in 40lb Sacks. Usage is Add 10-20kg of KWIKSEAL to every 1,000 litres of Make Up Fluid. Add KWIKSEAL through the hopper or directly in to a well agitated suction pit.
AMC SHUR-SEAL - is a blend of variable sized particles of ground paper that is applicable for use in all water based drilling fluid systems. Shur Seal can be used in concentrations up to 40kg / 1,000 litres of fluid make up in slug treatments or as an additive to the entire system. In most areas of lost circulation it is advisable to pre treat the system before drilling in to the lost circulation zone. Simple and easy to use. Can be added through the hopper or directly in to the pits. Range of different particle sizes. AMC SHUR-SEAL is packaged in 10kg Sacks. Usage is 5 to 25kgs per 1000ltrs od Drilling Fluid.
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