Measurement while drilling apparatus and method of using the same
View Patent ↗A method and apparatus used to transmit information to the surface from a subsurface location during the process of drilling a bore hole is described. A novel pressure pulse generator or “pulser” is coupled to a sensor package, a controller and a battery power source all of which reside inside a short section of drill pipe close to the bit at the bottom of the bore hole being drilled. The assembled apparatus or “MWD Tool” can be commanded from the surface to make a measurement of desired parameters and transmit this information to the surface by encoding data in pressure pulses generated by a pulser valve that includes a stator and a rotor which may be open and closed to create pressure pulses.
1. A wireless tool inserted down hole for providing drilling information during the drilling process comprising:
a rechargeable battery cartridge power source;
a pressure sensitive switch;
a sensor package;
a vibration sensitive switch;
a processor; and
a pulser valve comprising:
a stator with inlet passages that are orthogonal to the direction of fluid flow inside said drill string and a plurality of holes that are in line with the direction of drilling fluid flow; and
a rotor which resides inside said stator and has cylindrical blade surfaces which in a first orientation allow said drilling fluid to flow unobstructed through the slots orthogonal to fluid flow and in a second orientation, the rotor is rotatable and the blades are used to create an obstruction in the path of fluid flow through the orthogonal slots and thus generate a pressure pulse detectable at the surface.
2. The wireless tool of claim 1 wherein said rechargeable battery cartridge further includes an electrical power fuel gauge.
3. The wireless tool of claim 1 wherein said rotor is connected by a shaft to a geared electric motor drive which is used to rotate said rotor between the two orientations and the geared electric motor drive resides in a sealed air filled environment which is protected from said drilling fluid by a high pressure seal on said shaft and rolling element bearings to support axial and radial loads.
4. The wireless tool of claim 1 wherein said rechargeable battery cartridge power source is automatically turned off when removed from the well and automatically turned on when inserted into the well.
5. The wireless tool of claim 1 further including elastomeric isolators for dampening high frequency shocks and vibrations.