Abstract: An input stimulus provides a necessary input to a microprocessor implemented control system. The control system may fire one or more perforating guns of a perforating apparatus or it may change the state of a valve in a well testing apparatus. The input stimuli may comprise a pressure pulse transmitted down a well annulus disposed between a tubing string and a borehole casing, a pressure pulse transmitted internally down the tubing string, an output of a strain gauge for sensing the set down weight of a well tool disposed in the borehole, or an output of an inductive coupler connected to the well surface.

Abstract: A perforating gun having no firing head and no primary explosives is attached to a tubing string and the tubing string is run into a borehole. A new pump apparatus, having a firing head, is run into the tubing string until the pump firing head is adjacent the perforating gun. The firing head in the pump apparatus detonates, firing the perforating gun. If the firing head fails to detonate, one need only remove the pump apparatus from the tubing string in order to gain access to the firing head, for repair and replacement thereof. One need not remove the tubing string to gain access to the firing head.

Abstract: A new method of standalone perforating comprises the steps of lowering a perforator part-way into a borehole on a tubing string; when perforating is desired, connecting a wireline to the perforator; disconnecting the perforator from the tubing string; lowering the perforator into the borehole to the desired depth; attaching the perforator to the borehole casing or formation by setting an anchor on the perforator; disconnecting all wireline and associated apparatus from the perforator; withdrawing the wireline apparatus to the well surface; with the perforator standing alone in the well, firing the perforator into the surrounding formation; and dropping the perforator to the bottom of the well. A new apparatus for releasing the perforator from the tubing string includes a neutral release latch mechanism, and a new anchoring apparatus includes two interleaved coil springs having beveled shaped surfaces.

Abstract: A nuclear spectroscopic method and apparatus for determining hydrocarbon saturation or water saturation of a formation adjacent a well bore is disclosed. Near and far inelastic gamma ray spectra are detected in response to pulses of fast neutrons irradiating the formation and materials in the borehole. Near and far carbon/oxygen (C/O) ratios are extracted from each spectra using predetermined spectra of postulated elements. The near and far C/O ratios are combined to determine a representation of formation hydrocarbon saturation substantially corrected for borehole gamma rays produced by inelastic reaction of fast neutrons and hydrocarbons in the well bore. Shielding of near and far detectors is provided to make the near detector more sensitive to gamma rays emanating from borehole gamma rays and to make the far detector less sensitive to borehole gamma rays and more sensitive to formation gamma rays.

Abstract: A downhole seismic exploration device comprises a seismic detector such as a geophone and a magnetic clamp, supported by O-rings in an open cradle carrier which can be secured to a cable linking several such devices into an array. The array is lowered into a cased borehole and the magnetic clamps are operated to clamp the devices temporarily to the casing. Seismic signals detected by the geophones are transmitted to the surface via the cable, the O-ring supports acting to reduce or eliminate transmission of vibrations from the borehole fluid and the cable via the carrier to the geophone. The array is then unclamped and moved to another location in the borehole and the operation repeated. The magnetic clamp comprises a rotatable permanent magnet with radial poles disposed between a pair of parallel pole piece plates protruding on each side of the device and separated by non-magnetic blocks on eahc side of the magnet.

Abstract: A monopole transmitter for a sonic well tool includes an axial tube, a piezoceramic cylinder surrounding the axial tube, an endcap disposed at each end of and firmly contacting the cylinder, and an apparatus for holding the endcaps firmly against the axial tube. The endcaps firmly contact the axial tube without simultaneously contacting an upper bulkhead. The apparatus may include spring washers disposed between the bulkhead and at least one endcap, or it may include a spring disposed between a nodal mount and each endcap. A nodal mounting tube may be disposed around the axial tube, a ring being disposed at each end of the nodal mounting tube, each ring being disposed outside of the cylinder, the apparatus including a spring disposed between each ring and an endcap outside of the cylinder for biasing the endcaps in tension against a ring thereby holding each endcap firmly in contact against the axial tube.

Abstract: A perforating gun apparatus comprises a plurality of perforating gun, each gun containing at least one charge and a novel arming, testing and firing apparatus. The arming, testing and firing apparatus arms a first charge in a lowermost perforating gun; however, the arming of the first charge in the lowermost perforating gun allows a tester disposed at the well surface to determine the identity of the lowermost perforating gun to be detonated. Furthermore, the arming of the first charge in the lowermost perforating gun also enables the arming of a second charge in an adjacent perforating gun of the gun string. In the event the first charge is not armed as expected, the arming, testing and firing apparatus in the lowermost perforating gun bypasses the lowermost perforating gun and begins to arm the second charge in the adjacent perforating gun of the gun string.

Abstract: A new borehole correction software, for use in a well logging truck computer, obtains an accurate measurement of the true conductivity of a formation in a borehole by subtracting a correction term, which is a function of the mud conductivity, the borehole radius, the standoff distance, and an estimated value of the formation conductivity, from certain raw data received by a receiver thereby producing a set of eighteen complex output voltages which represent signals that would have been recorded from the receiver had there been no borehole.

Abstract: A perforating gun having no firing head and no primary explosives is attached to a tubing string and the tubing string is run into a borehole. A new well apparatus, having a firing head, is run into the tubing string until the firing head is adjacent the perforating gun. The firing head in the well apparatus detonates, firing the perforating gun. If the firing head fails to detonate, one need only remove the well apparatus from the tubing string in order to gain access to the firing head, for repair and replacement thereof. One need not remove the tubing string to gain access to the firing head.

Abstract: A sonic well tool includes a transmitter array, including at least one monopole transmitter and at least one dipole transmitter, and a receiver array for receiving sonic pressure wave signals from a surrounding borehole formation. A first attenuation and delay apparatus is positioned above the receiver array and a second attenuation and delay apparatus is positioned below the receiver array in the sonic well tool. The first attenuation and delay apparatus includes an attenuation member comprising a plurality of interleaved rubber and metal like washers for attenuating compressional and flexural waves propagating along a metal, center support rod to the receiver array and an inner housing comprising a bellows section having a corrugated shape and a thin transverse dimension for delaying the propagation of compressional and flexural waves along the inner housing to the receiver array.

Abstract: In order to properly treat the tubing of an oil producing borehole, and prevent hazard to personnel at the oil production site, the contamination of tubing by the formation of scale or radioactive deposits on the inner wall thereof is determined by measurement of the low-level radiation emitted by the scale and calculation of the radiation level which would be detected in the vicinity of the outer wall of the tubing in the absence of contributions by the radioactivity of surrounding earth formations. This is accomplished by a logging tool and method which includes a sonde which includes a detector and is lowered in the tubing to detect and count the gamma rays emitted by the scale or radioactive deposits at different depths in the borehole tubing.

Abstract: A perforating gun, adapted to be disposed in a deviated borehole, includes an intra-gun swivel located between a first plurality of charges and a second plurality of charges of the perforating gun. The swivel includes a first housing, a second housing, and thrust and radial bearings disposed between the surfaces of the first and second housing for allowing the first housing to rotate with respect to the second housing and therefore the first plurality of charges to rotate with respect to the second plurality of charges of the perforating gun.

Abstract: A safe-arm or quick arm system for a perforating gun includes a body containing a detonator and an adapter head containing an electrical plug and a detonating cord shell, the body and associated detonator being rotatable relative to the adapter head and associated detonating cord shell. Upon rotation of the body relative to the adapter head, the detonator moves from a start position to a transport position. In this position, the plug is not electrically connected to the detonator and the leads connected to the detonator are short circuited. The detonator is not adapted to receive electrical power. Upon further rotation of the body relative to the adapter head, the detonator moves from the transport position to an electrical contact position. In this position, the plug is electrically connected to the detonator but the detonator is not aligned with the detonating cord shell.

Abstract: A new method of standalone perforating comprises the steps of lowering a perforator part-way into a borehole on a tubing string; when perforating is desired, connecting a wireline to the perforator; disconnecting the perforator from the tubing string; lowering the perforator into the borehole to the desired depth; attaching the perforator to the borehole casing or formation by setting an anchor on the perforator; disconnecting all wireline and associated apparatus from the perforator; withdrawing the wireline apparatus to the well surface; with the perforator standing alone in the well, firing the perforator into the surrounding formation; and dropping the perforator to the bottom of the well. A new apparatus for releasing the perforator from the tubing string includes a neutral release latch mechanism, and a new anchoring apparatus includes two interleaved coil springs having beveled shaped surfaces.

Abstract: Nuclear spectroscopy method and apparatus for the stabilization of an energy spectrum, made from a signal, emitted by a radiation detector, and containing nuclear events, represented by pulses, whose amplitude is a measure of the energy of the particles, such as gamma rays, collected by the detector, the spectrum including at least a first reference energy peak coming from an ancillary nuclear source, wherein the method comprises: detecting the radiation under analysis by two detectors between which is placed the ancillary source; establishing at least one coincident spectrum corresponding to pairs of events simultaneously detected in both detectors and originating from the ancillary source; and stabilizing the coincident spectrum by using one energy peak of said spectrum as said first reference energy peak.

Abstract: Logging method and tool string for identifying and determining the concentrations of subsurface formation elements next to a borehole, by (i) using a low energy neutron source (either a chemical source, e.g. a .sup.252 Cf, or a deuterium-deuterium electronic source), and (ii) detecting and counting the delayed gamma rays resulting from the activation by the neutrons of atoms of at least one element of interest (e.g. aluminum). Two gamma ray detectors may also be disposed on either side of the low energy neutron source, for detecting and counting the prompt gamma rays resulting from the capture of neutrons by atoms of elements, such as Si, Ca, Fe, S, H, or Cl, Gd, Ti, or K.The low energy neutron source is used for both the "activation" and the "capture" measurements. The tool string may also include a natural gamma ray tool for the determination of uranium, thorium and potassium, and for measuring the background to be subtracted from the gross Al activation measurement.

Abstract: A method for determining the compensated density of a subsurface geological formation wherein the effect of borehole rugosity is reduced or eliminated utilizes the differences in the vertical response functions of the detectors at different distances into the formation. The method eliminates the contribution of the "shallow" formation region, irrespective of whether its properties are varying slowly or rapidly, without degrading the resulting vertical resolution. Furthermore, the method for determining such a characteristic of a subsurface geological formation does not require any additional or new measurements to be made, thus logging data from older wells can easily be reevaluated.

Abstract: Due to irregularities associated with the borehole of an oil well, a depth determination system for a well logging tool, suspended from a cable in the borehole of the oil well, produces a correction factor, which factor is added to or subtracted from a surface depth reading on a depth wheel, thereby yielding an improved indication of the depth of the tool in the borehole. The depth determination system includes an accelerometer on the tool, a depth wheel on the surface for producing a surface-correct depth reading, a computer for a well logging truck and a depth determination software stored in the memory of the computer. The software includes a novel parameter estimation routine for estimating the resonant frequency and the damping constant associated with the cable at different depths of the tool in the borehole.

Abstract: A bridge plug for sealing a well casing comprises a plurality of cups which tightly interfit together when a compressive load is applied to both opposite ends of the plurality of cups. Application of the compressive load to both opposite ends of the cups forces a first cup to fit into a second cup, the second cup to fit into a third cup, and the third cup to fit into a fourth cup, etc., thereby producing a single unitary plug which includes a plurality of tightly interfit cups. Further application of the compressive load to both opposite ends causes transverse expansion of the plurality of interfit cups to occur. When the cups contact the well casing wall, a permanent seal is achieved between the cups and the well casing wall. Anchor elements on both sides of the cups contact the well casing wall and permanently hold the interfitting cups in their compressed condition.

Abstract: The invention relates to a method of packaging a detonating cord comprising explosive material contained in a sheath, intended to meet safety regulations of air transportation. The detonating cord is wound on a support in such a manner that every portion of the detonating cord in the winding is spaced apart from the nearest portions which are substantially parallel thereto by a distance (a) lying in a range between the distance below which detonation is transmissible from one portion to the nearest portion, and the distance beyond which said containing sheath is no longer destroyed by the detonation of (a) nearest portion.