Abstract: Techniques are shown for determining the distribution of plural tracer isotopes located inside and outside a cased well borehole. Standard gamma ray spectra of plural tracer isotopes taken inside and outside (and possibly intermediate) a well borehole are fitted to an unknown gamma ray spectrum of a well having plural tracer isotopes used therein. Techniques using a priori knowledge of well geometry and not using such knowledge are disclosed for performing the analysis of the unknown well spectrum.

Abstract: A logging tool cable head for supporting the sonde on a cable is disclosed. It has an upper end which affixes to the cable and a lower end affixed to the sonde. The lower end supports an inwardly directed electrical grounding contact. The upper end supports a rotatable, indexed cam having facing upper and lower shoulders sized and located to bear against the contact, so that electrical contact is indicated on overloading. Indexing of the shoulders relative to the contact is achieved. There is also an adjustable centering spring system which locates the contact relative to the two shoulders.

Abstract: In a high pressure, high temperature detonator for deep well use, an improved device is disclosed. It includes an elongate housing with axial bore and an electrical conductor at one end. A first explosive initiator is electrically ignited. In turn, a sleeve having a transverse bulkhead aligns one or more secondary explosive transfer pellets. The transfer pellets cooperate in ignition of the detonating cord. The secondary explosive pellets and sleeve are configured into described shapes to focus the shock wave for cord ignition.

Abstract: A method and apparatus are disclosed for measurement of earth formation dip utilizing sonic techniques. At least three electroacoustic devices are utilized, each having an electroacoustic transmitter and a pair of electroacoustic receivers. The electroacoustic receivers are both located on one side of the transmitter and are preferably located vertically adjacent along a line with the transmitter. Transmitted acoustic energy is detected by the receivers and the elapsed time between detection by a first receiver and detection by a second receiver is determined. A correlation of the variations in elapsed times for each of the three electroacoustic devices is then utilized to calculate the formation dip at various depths.

Abstract: A photomultiplier tube stabilization circuit is set forth. It is particularly useful in downhole logging tools exposed to increases in temperature and to overcome component aging and drift. A high voltage power supply is connected for operation of a photomultiplier tube. The output of the PMT is amplified and applied to a set of comparators forming logic levels associated with threshold values affiliated with the spectral peak anticipated for the output data. The high voltage power supply is controlled upwardly or downwardly to vary operation of the PMT by means of a relatively simple control loop utilizing the comparators and means forming a control voltage for the high voltage power supply.

Abstract: Measuring apparatus for use with a motor driven rotary saw blade is disclosed so that dynamic measurements can be obtained while cutting lengthwise a core sample from a well borehole. The core sample is held, and the motor driven rotary driven saw blade is used to cut along the length of the core sample. Selected transducers are installed, and all the transducers connect to a CPU which also has connections with a clock, memory and recorder. Data is recorded either as a function of time or as a function of the location of the cutting tool along the core sample. Transducers include a current monitor for current operating the motor, a microphone measuring sound levels generated by the saw blade cutting through the core sample, a tension measuring device which provides the force which causes the motor to traverse along the length of the core sample, and also X, Y, Z coordinate vibration sensors such as accelerometers.

Abstract: A method and apparatus for dielectric investigation in formations adjacent a well borehole is set forth. In the preferred and illustrated embodiment, a microwave transmitter forms and output signal which is transmitted by a transmitter antenna in contact with the sidewall, the propagation into the formation from the transmitter antenna, the signal being received at a receiving antenna, and further including means for making measurements of amplitude and phase angle. Such measurements are used to determine an equivalent circuit representative of the formation between the transmitter antenna and receiver antenna; the equivalent circuit encodes valuations of resistivity, dielectric constant and magnetic permeability of the formation material. Multiple measurements can be made in a given formation, and the sonde can be moved steadily or periodically to make measurements at selected locations. Formation electrical parameters in adjacent formations can then be determined.

Abstract: A high temperature and high pressure fiber optic feedthrough is set forth to enable communication to the interior of a pressure housing making up a downhole logging tool. An optical fiber is stripped of protective wraps and coverings other than a fluorocarbon coating. It is inserted into a feedthrough fitting formed of an elongate body that feeds to the pressure housing. There is an axial bore which has an internal cavity at the upper end. This cavity receives a conic section of a resilient body which is deformable. Through the use of a specially designed syringe, the optical fiber is passed through this cavity and is positioned on the interior bore of the body. The resilient material is able to expand on application of pressure. The cavity is closed by means of a retainer nut and wear washer. When the nut is tightened, the resilient material extrudes around and along the optical fiber and seals against it to perfect a high pressure, high temperature seal against the intrusion of well fluids.

Abstract: A formation tester is set forth. It incorporates a probe having a surrounding elastomeric seal and snorkel for extension into formations. The probe connects with a sample line into the formation tester. On the sample line, a pressure sensor responds to pressure observed in the sample line and provides a signal for use in control of a motor controller opening and closing relative to hard valve elements and valve seats in a choking action to control flow in the sample line. The sample line then goes to a soft seat valve assembly having a valve element and a seat which delivers controlled sample flow into a chamber for storage within the formation tester.

Abstract: A side entry sub logging system has features for removing the cable should the drill pipe become stuck. A release sub is connected between the drill pipe and the side entry sub. A mandrel is carried in the side entry sub and extends into the release sub. Logging cable which passes through the side entry sub sidewall passage also passes through a passage in the mandrel. The mandrel will move between upper and lower positions. The connection between the side entry and the release sub will release when contacted by the mandrel in the lower position. This enables the side entry sub to be pulled straight upward, bringing along with it the cable. A plug dropped into the drill pipe from the surface blocks the passage through the mandrel, enabling fluid pressure to be applied to push the mandrel downwardly to actuate the connection between the release sub and the side entry sub.

Abstract: A formation tester is set forth. The device utilizes a snorkel extending from the formation tester to obtain a pressure test and collect samples from a formation of interest. The apparatus includes multiple sample storage containers, thereby cooperating with an equalizing valve to selectively isolate the snorkel from fluid and fluid pressures in the well. A control valve system in a hydraulic circuit operate backup shoes and a snorkel seal until testing is over to assure sealing against well fluid invasion in unconsolidated formation. A speed up sequence for both the backup piston and cylinder arrangement as well as the pad setting piston and snorkel arrangement is illustrated.

Abstract: A universal cable head is set forth which incorporates a stress relieving stinger on the end of a logging cable. The cable connects with wedge shaped members which grip the end of a cable within a housing. Electrical conductors, seven in number, extend from the end of the cable into the housing and are exposed in an internal cavity. In the cavity, they connect with a set of boots at the back end connecting with feedthrus by bayonet connection, the feedthrus being supported on a transverse bulkhead, and the feedthrus all extend through the bulkhead to locate male plugs within a circular housing. A rotatable threaded sleeve is on the exterior for connection with a mating female member. All of this structure connects universally to mating female connectors on downhole logging tools to provide the requisite number of conductors for downhole logging operations.

Abstract: A method and apparatus are disclosed for carrying out the seismic exploration of the strata which surrounds a borehole during the drilling of that borehole. A compressional mode jar mechanism is disposed in a drill string above a drill bit. Sufficient weights to cock and actuate the jar are disposed both below and above the jar mechanism respectively. A telescoping joint above the jar prevents the impact on the drill bit from propagating up the drill string and multiple geophones at the surface are utilized to receive the seismic waves generated by the impact of the drill bit within the borehole. In a preferred mode of the present invention, an additional geophone is disposed within the drill string proximate to the drill bit to detect the "first break" of the impact thus generated.

Abstract: A flexcompressional acoustic transducer is set forth. In the preferred and illustrated embodiment, multiple parallel magnetostrictive rods provided with coils are coupled through a plate affixed to a radiating element. The radiating element in one embodiment is an elongate hollow cylinder which is closed at both ends. Vibrations from the magnetostrictive members cause the cylinder to radially flex, creating an omnidirectional acoustic wave transmitted radially outwardly, the apparatus being positioned in a sonde for connecting an acoustic wave front through the wall of the sonde for transmission into the surrounding wellbore fluids and the adjacent formations.

Abstract: A tracer injection method is set forth and is practiced by using spaced end located injectors on a sonde having spaced detectors along the length of the sonde. The injectors inject radioactive isotopes which are distinguishable from one another at the detectors. The method contemplates simultaneous injection of different isotopes, making measurements to determine fluid flow velocity in the casing, and selecting peaks to obtain measurements of the fluid flow velocity in leaks through the casing into external channels along the casing.

Abstract: A method of radioactive well logging for use in well operations wherein hydraulic fracturing material, including radioactive isotopes, is injected from a steel-cased well bore 31 into surrounding earth formations 33. Low energy gamma ray emitting radioisotopes are selected for tagging the liquids phase of the fracturing material and high energy gamma ray emitting radioisotopes are selected for tagging the solids phase. The relative amount of low energy radioisotope material inside the well bore 31 relative to the amount outside the casing 35 is determined to minimize the interfering effects of borehole tracers in determining concentrations of the high energy tracers in the formations. The procedure includes detecting the intensity of gamma radiation from the tracers in the borehole and surrounding formations by a detector 38 in the borehole in proximity to the injection zones and obtaining data representative of the radiation intensity.

Abstract: In logging operations in a well borehole where difficulties arise in retrieval of the logging apparatus, drilling through the logging tool is sometimes necessary. This disclosure sets forth a radioactive source material which permits this remedial step. The radioactive source material is either a short half life radioactive isotope or is in fluid form. In fluid form, it is purged out of the sonde by means of a motor controller triggered into operation to operate a piston and cylinder pump arrangement. The outlet from the cylinder is through a flow line and check valve. The purged radioactive source material is then flushed to the bottom of the well borehole and is ideally forced into a selected formation for disposal, thereby safely removing the radioactive materials from the sonde to permit destruction of the sonde.

Abstract: A fluid flow velocity measuring device is shown. In the preferred and illustrated embodiment, an elongate body receives a removable spinner cartridge assembly. The assembly is formed of an elongate sleeve surrounding a rotating shaft supported by bearing assemblies at opposite ends of the shaft. The shaft supports a spinner. Particular sizes of spinners are calibrated to a particular flow velocity ranges and density of material. The insert is held in position by a compressed spring behind the insert so that fluid flow is directed from an inlet port in the tool adjacent a petal basket, along an axial passage in the tool, and through the spinner and out through an outlet port.

Abstract: A process for processing a dipmeter curve is shown in the preferred embodiment. In a curve, line segments are drawn between curve minima, a second set of line segments are drawn between minima in the first segments, and this is repeated to desired number of levels. When finished, line segments are numbered and become a branched tree. This tree is reorganized to form an event tree which is easily converted into a stored digital value and is processed for correlation with other curves.

Abstract: A method and apparatus is disclosed for avoiding problems caused by a logging tool sticking in a borehole and subsequently accelerating when it becomes free. Such problems give rise to measurement errors and loss of data, particularly when the tool is in the vicinity of ground discontinuities where the data is especially valuable. In accordance with the method and apparatus, data is stored in the tool as it is moved within the borehole, the data being stored in a manner which varies in accordance with any difference between the actual motion of the tool in the borehole and the apparent motion of the tool as measured at the surface. The stored data is transmitted from the tool to the surface at a rate within a transmission bandwidth capacity of a communication link. According to one arrangement, means are provided for shifting the writing position of data entered into a memory, the shifting means being responsive to an error signal related to any difference between the actual and apparent motions of the tool.