Much improved drill bit design is possible with a mud pump.
The reason we have to leave the middle of our “drill bit” open when we are washing/drilling a well with two hoses is that at the end of the drilling process we need to be able to slip a wellscreen down through the pipe and “bit” and then pull the drillpipe up and out of the ground. Otherwise the sand at the bottom of the hole will quickly collapse when we pull the drillpipe out and we won’t be able to get a well screen back down to the bottom of the hole.
We could achieve much more effective drilling if we could use a point or some other shape in the middle of the bit. Basically with teeth cut in the end of a pipe, we are grinding away at the circumference of the hole and just using the general associated loosening to evacuate the center of the hole. This is obviously not the most efficient way to do this.
With a mud pump and a re-circulating drilling fluid system, everything changes. It gets much easier. Drilling is more efficient. We can add bentonite to the drilling fluid and solidify the sandy walls of the hole so they won’t collapse when we remove the drill bit.
Using this techique permits us to drill the hole with a more efficient drillbit that will mechanically eat away the entrie area of the hole, not just the edges. After we drill the hole, the bentonite will hold the hole open so we can remove our drilling pipe and replace it with out well screen pipe. Here are some photographs of the drill bit I use. It was fabricated by a local welding shop for $55.00.
MUD PUMP DRILL BIT – NOTE THE SET SCREW
MUD PUMP DRILL BIT
DESIGNED FOR MINIMAL FRICTION
WHEN REMOVING FROM HOLE
John, in Brandon, Mississippi sent this picture of a drill bit that he fabricated. It has square pieces of carbide on the outside and he welded a piece across the middle and ran quarter inch bolts through it. This looks like a great bit for mud pump drilling!
John’s Drill Bit
EDSON FROM BRAZIL SUBMITTED THIS DRILL BIT.
(crafty no welding design!)