Airdrilling空气钻井.pptVIP

Air Drilling(空气钻井） 1 Hole Cleaning 2 Equipment 3 Drilling Practices 4 Problems 5 Gas Type 6 Mist Drilling Air compression equipment Drillstring valves BOPS and control heads Returns handling system Compressors and Boosters Required to compress air at ambient conditions to a pressure suitable for air drilling Usually a combination of one or more compressors and a booster is used Reciprocating and rotary screw most commonly used to compress atmospheric air to 100 to 300 psig Boosters are positive displacement compressors used to increase the delivery pressure. Air Compression System Layout Drillstring Valves A drillstring “spring” type float valve should always be run near the bottom of the drillstring to prevent backflow (solids and/or formation fluids) up the string. A string valve (flapper type) is generally run in the upper section to minimize the time required to bleed the string down during connections. The spring that closes the flapper is typically removed since the compressed fluid in the string will force it closed when required. This allows wireline tools to be run (with care) once the pressure has bled off and the flapper is hanging open. Blooie Line Jets Making Connections It is a good practice to get “bottoms up” prior to shutting down for the connection. With the air off, the cuttings in the annulus will fall around the BHA. If the pipe is raised the cuttings will be jammed and packed making stuck pipe more likely. Always wait until returns are established prior to picking the pipe up off the slips. An increase in standpipe pressure when breaking circulation will indicate cuttings packing. Tripping Considerations If the well is making gas, the string must be pulled through the rotating head element. The gas will be flowed away from the rig via the blooie line. The rubber element will need be removed to pull the BHA. When doing so, the primary jet should be used to remove gas from the surface of the well. If the well is not making gas, the rubber eleme