Apparatus for measuring the azimuth and inclination of a borehole

Claim 1

A DRILLING DRIFT INDICATOR FOR USE IN DRILLING A BOREHOLE WHICH COMPRISES: A HOUSING MEMBER, SAID HOUSING MEMBER HAVING A FIRST PASSAGES MEANS FOR CONVEYING FLUID FROM ONE END OF THE HOUSING MEMBER TO THE OTHER END, ONE PORTION OF SAID PASSAGE MEANS HAVING A FIRST RESTRICTION, A SECOND RESTRICTION, A THIRD RESTRICTION, AND A FOURTH RESTRICTION, SUCH RESTRICTIONS BEING EQUALLY SPACED; A FIRST HYDRAULIC FLUID CYLINDER WITHIN SAID HOUSING MEMBER AND HAVING AN UPPER AND A LOWER END; A PENDULUM COMPARTMENT WITHIN SAID HOUSING MEMBER; A COMPASS COMPARTMENT WITHIN SAID HOUSING MEMBER; A PLUNGER ROD WITHIN SAID HOUSING MEMBER EXTENDING AT LEAST FROM SAID FIRST RESTRICTION DOWNWARDLY THROUGH THE UPPER END OF SAID CYLINDER; A CAP MEANS MOUNTED ON THE UPPER END OF SAID PLUNGER ROD; A PISTON MOUNTED ON THE LOWER END OF SAID PLUNGER ROD AND WITHIN SAID CYLINDER; MEANS BIASING SAID PISTON UPWARDLY WITHIN SAID CHAMBER; A DISCHARGE CONDUIT IN FLUID COMMUNICATION WITH THE CYLINDER BENEATH SAID PISTON; A FIRST CONDUIT MEANS ESTABLISHING FLUID COMMUNICATION BETWEEN SAID DISCHARGE CONDUIT AND THE INTERIOR OF SAID CYLINDER ABOVE SAID POSTON, SAID FIRST CONDUIT MEANS HAVING A FIXED RESTRICTION THEREIN; A SECOND CONDUIT MEANS HAVING A VARIABLE RESTRICTION THEREIN AND CONNECTING SAID DISCHARGE CONDUIT WITH SAID CYLINDER ABOVE SAID PISTON; A THIRD CONDUIT MEANS ESTABLISHING FLUID COMMUNICATION BETWEEN SAID DISCHARGE CONDUIT AND THE INTERIOR OF SAID CYLINDER ABOVE SAID PISTON; A PENDULUM PIVOTALLY SUPPORTED WAITHIN SAID PENDULUM COMPARTMENT; MEANS TO VARY THE RESTRICTION WITHIN SAID SECOND CONDUIT MEANS IN RESPONSE TO THE POSITION SAID PENDULUM WITHIN SAID PENDULUM COMPARTMENT; A ROD LOADED WITH AN ECCENTRIC WEIGHT AND ROTATABLY MOUNTED WITHIN SAID COMPASS COMPARTMENT; MEANS TO RESTRICT THE FLOW WITHIN SAID THIRD CONDUIT MEANS AS A FUNCTION OF THE POSITION OF THE ECCENTRIC WEIGHT; A FIRST DAMPENING FLUID WITHIN SAID PENDULUM COMPARTMENT; A SECOND DAMPENING FLUID WITHIN SAID COMPASS COMPARTMENT; MEANS FOR EQUALIZING THE PRESSURE OF SAID FIRST DAMPENING FLUID AND SAID SECOND DAMPENING FLUID WITH THAT OF THE PRESSURE WITHIN SAID CYLINDER ABOVE SAID PISTON; VALVE MEANS THREE POSITIONS, ONE POSITION FLUIDLY CONNECTING SAID DISCHARGE CONDUIT WITH SAID FIRST CONDUIT MEANS, A SECOND POSITION CONNECTING SAID DISCHARGE CONDUIT WITH SAID SECOND CONDUIT MEANS AND A THIRD POSITION CONNECTING SAID DISCHARGE CONDUIT WITH SAID THIRD PASSAGE MEANS; MEANS TO ACTUATE SAID VALVE MEANS SUCH THAT SAID VALVE IS IN ITS FIRST POSITION WHEN SID CAP MEANS IS BETWEEN SAID FIRST AND SAID SECOND RESTRICTION, IN ITS SECOND POSITION WHEN SAID CAP MEANS IS BETWEEN SAID SECOND AND THIRD RESTRICTIONS AND IN ITS THIRD POSITION WHEN SAID CAP MEANS IS BETWEEN ITS THIRD AND FOURTH RESTRICTIONS; A SECOND PASSAGE MEANS BETWEEN THE CYLINDER ABOVE SAID PISTON AND THE FIRST PASSAGE MEANS FOR CONVEYING DRILLING FLUID THROUGH THE TOOL; AND A DIAPHRAGM WITHIN SAID SECOND PASSAGE MEANS.