Abstract: A sidewall contact parameter tool, adapted to be disposed in a mud-filled wellbore, includes a pad assembly, in accordance with the present invention, which is adapted to cut through mudcake and measure a parameter of a formation disposed under the mudcake. The wellbore wall includes a mudcake and an earth formation disposed under the mudcake. The pad assembly includes at least one formation parameter sensor, and the formation parameter sensor includes a base portion and a knife edge portion integrally connected to the base portion. The base portion of each formation parameter sensor is adapted to contact a surface of the mudcake but the knife edge portion is adapted to cut into the mudcake and contact or penetrate a surface of the earth formation disposed under the mudcake. The knife edge portion of each sensor includes an internal space or pinhole aperture, and a parameter sensing apparatus disposed within the internal space or aperture.

Abstract: An automatic tubing release mechanism is adapted to be disposed in a wellbore between a tubing, on one end, and a perforating gun, on the other end. The release mechanism includes a frangible breakup tube, firing head positioned above the breakup tube, and the perforating gun positioned below the breakup tube when the release mechanism is disposed in the wellbore. A detonating cord is interconnected between the firing head and the perforating gun via the breakup tube. When the firing head detonates the perforating gun, the breakup tube shatters.

Abstract: A nuclear magnetic resonance (NMR) logging system includes a NMR logging tool adapted to be disposed in a borehole and a processing system adapted to be disposed on the surface of the borehole, the logging tool including a microcomputer, the processing system including a computer; and a signal processing system in accordance with the present invention having a first part stored in the downhole microcomputer of the logging tool and a second part stored in the surface oriented computer of the processing system. In the downhole microcomputer, using the first part of the signal processing system, a plurality of signal plus noise amplitudes are produced from a set of measured spin echo data, and a plurality N.sub.w of the window sums I.sub.m,m+1 are produced from the signal plus noise ampltudes, the window sums being transmitted uphole to the processing system.

Abstract: A hydraulic safety pin is interconnected between a device, such as a pressure controlled firing head associated with a perforating gun, and a small diameter tubing in a wellbore. When, the small diameter tubing is filled with fluid under pressure, the hydraulic safety pin allows the fluid to fill the small diameter tubing but prevents the pressure of the fluid in the small diameter tubing from accidentally detonating the firing head when the pin is disposed in a first position; however, when the tubing is already filled with fluid under pressure, the hydraulic safety pin allows the pressure of the fluid in the small diameter tubing to detonate the firing head when the pin is disposed in a second position. The hydraulic safety pin may be installed in a special coupling, and multiple special couplings may be used in a tool string disposed in a wellbore.

Abstract: A test string section for a well comprises a circulating valve (40) including a mandrel (60), a rupture disk (68), and a series of ports (56). The valve is arranged above a packer. A second port (50) is arranged on a pipe section (44) below the packer and a flow tube (52) extends through the internal bore (66). On rupturing the rupture disk, the port (56) is opened whereby mud can be pumped into a rathole via the port to kill the rathole while the seal of the packer against a wall of the wellbore is still intact and the packer remains in a set condition.

Abstract: A logging method for measuring the resistivity of formations having a borehole passing therethrough, in which a logging sonde is suspended inside the borehole by means of a cable, the sonde comprising electrodes for injecting alternating currents into the formations, these electrodes comprising a central electrode A.sub.0 and focusing electrodes, together with a return electrode B and a potential reference electrode N, one of which is placed above the sonde and the other of which is placed at the surface, and producing a resistivity log from the current I.sub.0 emitted by the central electrode and the potential difference between the sonde and the reference electrode. The method further comprises the step of producing a second log of the resistivity with the return and potential reference electrodes being placed as for the first log and under conditions such that the investigation depth is different from that applicable to the first log. The invention is applicable to correcting the Groningen effect.

Abstract: A new method and apparatus for performing a drill stem test in an open (not cased) borehole are disclosed. When the borehole is initially drilled, the drilling process induces a skin damage near the external surface of the open (not cased) wellbore. It is necessary and desirable to bypass, reduce, or eliminate the skin damage in order to provide a free or natural flow of well fluid from the reservoir in the formation into the wellbore. However, in order to determine the degree of skin damage which exists near the external surface of the wellbore, reservoir parameters such as pressures, temperature and flowrates of the formation fluid flowing from the reservoir into the wellbore is first measured in the presence of the skin damage. The skin damage is then bypassed, removed, eliminated, or reduced by, for example, perforating the external surface of the wellbore.

Abstract: The invention relates to reservoir evaluation and is more specifically directed to a method of characterizing the individual response of a layer of a multi-layer hydrocarbon reservoir traversed by a well, based on downhole flow rate and pressure measurements performed during transient tests initiated by changes in the surface flow rate of the well, the flow rate being measured above said layer during one transient test and below said layer during another transient test.

Abstract: A nuclear apparatus for obtaining qualitative and quantitative information related to an element of earth formation surrounding a borehole, comprising: (1) a neutron source for irradiating the formation with neutrons of sufficient energy to activate atoms of at least a given element; (2) at least two (preferably four) detectors longitudinally spaced from said source, for detecting the gamma rays emitted during the activation reaction; (3) means for assigning a maximum number of counts for each detector and for establishing a relationship between these maximum number of counts and the corresponding instant of time counts for each detector; and (4) means for deriving from the relationship qualitative information related to the element.The relationship is approximately a straight line, the slope of which is representative of the element of interest. The amplitude of the counts is representative of the quantity of the activated element and of the radial distance between the activated atoms and the borehole.

Abstract: A borehole correction software of a multipole sonic well tool adapted to be disposed in a borehole determines a true, corrected value of shear wave slowness from a measured uncorrected shear wave slowness value by first building a look up table comprising hole diameter, measured synthetic shear wave slowness and correction factor, and using the table in a system including the look up table and a multiplier to determine a bias, which bias is subtracted from the measured uncorrected shear wave slowness to produce an output medium reflecting a true, corrected value of shear wave slowness. The measured uncorrected shear wave slowness values are input to the look up table. For a given hole diameter, the measured uncorrected shear wave slowness is matched to a measured synthetic shear wave slowness, and a value of correction factor is determined from the table. The correction factor is multiplied by the measured uncorrected shear wave slowness, via the multiplier, and a bias figure is determined.

Abstract: A new pump or injection apparatus is adapted to be connected between a pipe and a valve and is adapted to either pump well fluids from a wellbore or inject fluids into a formation traversed by the wellbore. The valve includes a full bore passage and a surrounding inlet flow channel.

Abstract: A shaped charge includes a case, an explosive material packed against the inner wall of the case, and a liner for lining the explosive material, where the liner includes Bismuth and Copper powders as constituent elements. The Bismuth element replaces a Lead element which is normally present as a constituent element in prior art shaped charge liners. Bismuth is superior to Lead because all environmental concerns, with respect to the deposition of Lead in a formation, have been eliminated.

Abstract: A nuclear spectroscopy method and apparatus for obtaining qualitative and quantitative information related to water flow, comprising the steps of:(1) irradiating the water flow with a source of neutrons of sufficient energy to interact with oxygen atoms in the water according to the activation reaction O.sup.16 (n,p)N.sup.16 ;(2) detecting and counting, with at least at a detector, the gamma rays emitted during disintegration of N.sup.16 ;(3) making a plot of the counts versus time; and(4) deriving from said plot information related to said water flow.The irradiating is advantageously interrupted after a given period of time, and is preferably immediately followed by the detection. The water flow velocity "V" is calculated from the formula V=d/t, where "d" is the distance between the source and the detector(s), and "t" is the time period between the irradiation and the time corresponding to a characteristic on said plot, representative of the water flow and departing from the N.sup.16 exponential decay curve.

Abstract: A passive flowmeter for determining the flow rate and the direction of flow of a fluid in a well comprises a magnetic generator (29) suitable for being rotated about an axis (RR) and including at least one north pole (N) and at least one south pole (S) lying flush with a first plane (P1) perpendicular to the axis (RR). The flowmeter also includes a magnetic detector (33) constituted by a magnetic core (34) supporting a coil (40) and extended by two magnetic terminal portions (36, 38) having spaced apart end surfaces which are disposed substantially flush with a second plane (P2) facing said first plane. The end surfaces of a terminal portion have areas which are different from the end surfaces of the other terminal portion. The poles of the magnetic generator (29) are angularly spaced about the axis (RR) by an angle such that the variations of magnetic flux generated through the coil (40) by rotation of the magnetic generator (29) have a cycle ratio which is other than unity.

Abstract: An explosive diode transfer system is interconnected between adjacent perforating guns of a modular perforating apparatus. The explosive diode transfer system includes a downwardly directed shaped charge, a booster, and a multi-density barrier interposed between the shaped charge and the booster. The multi-density barrier includes a first metal layer and a second metal layer spaced from the first metal layer thereby defining a sealed air-space between the first and second metal layers. The first metal layer, air space, second metal layer combination represents a plurality of different density barriers or layers which are collectively designed to prevent a first detonation wave, propagating from the booster to the shaped charge, from propagating therethrough, but nevertheless to allow a jet, propagating from the shaped charge to the booster, to propagate therethrough.

Abstract: A maximum entropy method (MEM) determines a more accurate formation parameter profile, such as conductivity profile, of a formation. The MEM method employs an iterative procedure for determining the formation parameter profile. At each interation, theoretical logs are computed and compared with the measured log data. One iterative step is the calculation of a forward model to predict the response of the tool in a given assumed formation. Another iterative step is the solution of a set of linear equations to update the assumed formation parameter in the formation to produce closer agreement to the measured data. In a solution iterative step, the input is the measured values of the voltages denoted by V.sub.k.sup.j and the calculated values V.sub.k.sup.j, the output is an improved formation parameter profile .sigma..sub.l.sup.(n+1). In the solution step, a set of linear equations is solved for intermediate quantities q.sub.l.sup.(n), related to .sigma..sub.l.sup.(n) by the formula.sigma..sub.l.sup.(n) =.pi.

Abstract: A hydrostatic setting tool, adapted for setting an anchored device in a wellbore, includes a housing having a pair of ports exposed to well fluid at hydrostatic pressure. The ports lead to a shoulder of a setting mandrel. A barrier is disposed diametrically across the setting tool and an oil chamber is disposed between the setting mandrel and the barrier. The barrier includes an oil metering orifice disposed through a center thereof. A selectively operable apparatus, initially disposed in a closed position and blocking the oil metering orifice, is adapted to change from the closed position to an open position in response to a current delivered thereto from the well surface. An air chamber is disposed on the other side of the barrier. The well fluid places hydrostatic pressure on the shoulder of the setting mandrel thereby placing the same pressure on the oil in the oil chamber.

Abstract: In the representative embodiment of the method and apparatus of the invention which are disclosed herein, a well tool arranged for suspension in a well bore from a cable includes a mandrel that is telescopically arranged on the tool body and is operable after the tool is stationed in a well bore to be shifted upwardly and downwardly by the cable. A pressure-responsive actuator is arranged on the tool for being released in response to an initial downward movement of the suspension cable for rapidly extending an anchor on the tool body into engagement with the well casing. Thereafter, a successive upward movement of the suspension cable is effective for releasing the pressure-responsive actuator for slowly traveling to a position in the tool body where a firing pin on the body is released for detonating an impact-actuated explosive device on the tool only after a predetermined time delay following the upward cable movement.

Abstract: Method and apparatus for logging a formation interval in a well when the fluids are produced therefrom by a downhole pump. The method comprises lowering into the well a tubing (10) carrying a downhole pump (14) and a logging assembly, the logging assembly comprising a support (31) releasably latched in the tubing at an upper position located a predetermined distance above the pump, a cable section (26) attached to the support and passing from the bore of the tubing to the well bore along the pump through a sealed passage (25), and a well logging tool (15) attached at the lower portion of the cable section in a protecting sleeve (28). When the pump is at the correct depth in the well, a cable is passed from the surface through the tubing and connected to the support (31) by means of a wet connector. The support is released from its upper latching position and lowered in the tubing for bringing the logging tool (15) to the formation interval (12).

Abstract: In a well logging truck computer which phroduces an induction log, a dip correction algorithm, stored in a memory of the computer, corrects an error introduced in the induction log by dip effect. The dip effect error is introduced into the induction log when an array induction tool is disposed in a deviated borehole at an apparent dip angle with respect to a formation having a plurality of bedding planes, and subsequently develops formation parameter data. This formation parameter data, which contains the dip effect error, is displayed on the induction log. The dip effect algorithm eliminates the dip effect error by multiplying or convolving inverse filters "h" as a function of dip angle "a" with a plurality of the formation parameter data "sigma(j-n)" to thereby produce a corresponding plurality of corrected formation parameter data "sigma.sub.F ", the corrected formation parameter data being reproduced on an induction log output record medium.