Radiator fluids, transmission fluids, and lubricating oil must be periodi- 

 cally changed in compressors, generators, pumps, and main power drives. These 

 fluids are usually stored in waste barrels for removal by truck. 



In marsh sites, a sump located inside the levee collects the runoff from 

 rain and levee seepage. If any oil collects in the sump, it is vacuumed off 

 and placed in a waste-holding facility. Clean water (if it is not brine) is 

 usually pumped out of the sump into the marsh. Rigs are built with either a 

 curb around the work area leading to a drain and liquid storage sump or with a 

 drip pan that drains to a storage sump. The actual activities on the deck 

 result in the spilling of small amounts of drilling mud and other fluids. In 

 addition, the area is kept clean by frequent washing with water. These liquids, 

 as well as rainwater, may collect and are handled in the same manner as the 

 sump described previously. 



Drilling fluids. A considerable amount of the area at any drilling site 

 (as much as 70 percent) is occupied with equipment for the mixing, storage, 

 pumping, filtering, and treating of mud. The mud takes a circuit through the 

 equipment, beginning with the suction pit and leading to the pump. The mud is 

 pumped under pressure up through a standpipe on the rig itself, through a kelly 

 hose, into the swivel, down through the hollow kelly, and into the drill pipe. 

 The mud travels to the bit where it is squirted toward the cutting area, and 

 then it travels back up the hole, outside the drill pipe to the surface. From 

 the annul us at the wellhead, the mud travels to a shaker table where the cuttings 

 are filtered out. The mud falls through the shaker screens, may pass through a 

 desander and desilter, and returns to a settling tank where small -diameter 

 particles fall to the bottom. The mud may be treated chemically and then 

 proceed to the suction pit. 



Muds may contain many types of material, but they are basically a mixture 

 of water, clays, chemicals, and weighting substances to give a specified density. 

 For specialized uses, muds may be acidic, neutral, or basic, or they may have 

 an oil rather than water base. Mud may contain many different types of materi- 

 als such as bentonite, tannin, caustic soda, cornstarch, redwood fiber, wood 

 fiber, lime, corn, acid, phosphate, clay, sawdust, cottonseed hulls, and barite. 



A well may produce mud if clays and shales are drilled, and more drilling 

 mud than is really necessary may result if dilution is required. Sometimes 

 extra mud may be needed, particularly if some strata are yery permeable or if 

 all drill pipe is removed from the holes. Excess fluids may be stored in a 

 reserve pit to be used at another time. 



Mud may be a significant investment for a driller. Thus, if other wells 

 are being drilled nearby, a drilling operator may sell some of the mud if 

 operations are about to be concluded. In bay areas, mud uncontaminated by 

 hydrocarbons may be disposed of in the water. In upland areas or marsh sites 

 with pits, some of the mud can be left to dry in the pits. Mud may need to be 



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