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:
an electrical 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 a longitudinal axis of a drill string and a plurality of holes that are in line with the longitudinal axis of said drill string; 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 passages orthogonal to the longitudinal axis of said drill string 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 further including 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 electrical 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.
6. A pulser valve inserted down hole for downhole tools which creates pressure pulses in drilling fluid comprising:
a stator with inlet passages that are orthogonal to a longitudinal axis of a drill string and a plurality of holes that are in line with the longitudinal axis of said drill string; 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 passages orthogonal to the longitudinal axis of said drill string 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 passages and thus generate a pressure pulse detectable at the surface.
7. A method for transmitting drilling information to the surface from a subsurface location via drilling fluid pulses during the process of drilling a bore hole using a measurement while drilling tool inserted down hole in a drill string near the drilling bit wherein said tool comprises a sensor package, power source, vibration detector, and pulser valve wherein said pulser valve includes:
a stator with inlet passages that are orthogonal to the longitudinal axis of said drill string and a plurality of holes that are in line with the longitudinal axis of said drill string;
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 passages orthogonal to the longitudinal axis of said drill string and in a second orientation the rotor is rotated and the blades are used to create an obstruction in the path of fluid flow through the orthogonal passages and thus generate a pressure pulse detectable at the surface; and further comprising the steps of:
a) stopping the rotation of said drill string;
b) stopping the pumping of said drilling fluid;
c) waiting until said vibration detector determines end of vibrations signaling said sensor package by said vibration detector that vibrations have stopped;
d) turning on sensor package;
e) gathering said drilling information by said sensor package;
f) starting said pumping said drilling fluid;
g) detecting vibration by said vibration detector;
h) signaling said pulser valve to transmit said drilling information; and
i) transmitting said drilling information by said pulser valve via said pressure pulses in said drilling fluid.
8. The method of claim 7 wherein said step c waiting is a period of 1 minute.
9. The method of claim 7 wherein before the stopping of the rotation of said drill string, the further step of lifting said drill bit off bottom a few feet is included.
10. The method of claim 9 wherein after the lifting of said drill bit, the further step of circulating said drilling fluid to clear cuttings.
11. The method of claim 7 wherein said information includes angle, inclination, and bottom hole temperature.