Abstract: A firing head for a perforating gun includes a detonating block having a first end and a second end, with the second end being structured and arranged so as to be located adjacent to a detonation material. A central passage extends through the detonating block from the first end to the second end. A detonator is located and restrained in the passage so as to be adjacent to the detonating material. At least one venting passage extends from the central passage to an exterior of the detonating block.

Abstract: A directional drilling control system allows dynamic orientation of downhole drilling equipment in unstable or corrupt natural magnetic fields without the use of gyroscopic measurement devices. The system is especially suited for sidetracking wells. The system includes a permanent or retrievable whipstock having referencing magnets embedded along the centerline of its face, and a measurement while drilling (MWD) instrument assembly. The instrument assembly contains at least one sensor which can accurately determine orientation of the mud motor relative to the reference magnets. The relative positioning of the mud motor is transmitted to the surface by way of a steering tool or MWD telemetry system. The direction of the mud motor or tool face is adjusted by turning the drill pipe at the surface. As drilling progresses, shifts in the orientation of the mud motor due to reactive torque at the drill bit will be indicated in real time so that adjustments may be made at the surface as required.

Abstract: A downhole tool containing instruments and a pulser is landed within a string of drill pipe. The pulser has a pulser body and an orifice on a lower end. A piston slides within a bore in the body and has a signal poppet on a lower end. In an extended position, the signal poppet extends into and obstructs the orifice to reduce the flow of drilling fluid. In an open position, the signal poppet does not obstruct the orifice to increase the flow of drilling fluid. A bidirectional solenoid valve is located above the piston and has upper and lower electromagnetic coils and an axially moveable rod. The rod is movable between a closed position in an opening in the body and an open position away from the opening. The rod is moved to both positions in response to the instruments which sends signals to the coils. The mud pulser also has an on/off flow switch which is actuated by the commencement of mud circulation. Initially, the rod is in the closed position.

Abstract: A measurement while drilling tool has upper and lower centralizers secured to an upper end. Each centralizer comprises three major components: a housing, a tapered nose, a shaft which is slides in a bore of the housing, and a set of fingers around the shaft. The nose of the lower centralizer is tapered at a greater angle than the nose of the upper centralizer. An upper end of each finger is pivotally attached to the shaft. The fingers slidingly engage the nose when they are not in a retracted position. The centralizers are suspended in a drill pipe so that the shafts are fully extended from their housings. With the shafts extended, the fingers retract. Prior to drilling, the tool is lowered until it lands in a sub which causes the lower shaft to slides downward into the housing. The lower fingers move outward to engage the drill pipe without wedging against it.

Abstract: A downhole measurement tool is lowered into a well through a drill pipe. The tool has at least two modules which are joined by a flexible linkage. The linkage has two subs, each of which has an electrical connector for the modules. Each sub has a hub that is threaded. A threaded retainer nut retains each connector. Each nut has a hub that is threaded and is smaller in diameter than the sub hub. A coiled inner spring threadingly engages each nut hub. A coiled outer spring surrounds and threadingly engages each sub hub. The outer spring surrounds the inner spring and is wound in an opposite direction of the inner spring. The springs are embedded within an elastomeric member. The inner spring is dimensioned such that, for a selected lateral bend prior to installation with the outer spring, the inner spring will twist a selected angle in a first twist direction.