Abstract: A housing for an acoustic logging tool apparatus for use in a well bore is disclosed. The logging tool comprises an acoustic transmitter and one or more acoustic receivers located a fixed distance from the transmitter and an elongated tubular housing having a transmitter area, an intermediate area and a receiving area. The tubular housing has a plurality of interruptions or holes in the longitudinal continuity of its wall to delay the acoustic energy passing from the transmitter to the receiver along the housing. The receiving area of the housing further having means for reducing secondary acoustic noise produced by acoustic scattering between the intermediate area and the receiving area.

Abstract: An electrical induction sonde for measuring a characteristic of an earth formation traversed by a borehole having improved vertical resolution and excellent depth of penetration. The sonde has two or more transmitter-receiver spacings preselected to provide at least two separate induction signals received from the formation that, when combined, produce a response function indicative of formation physical properties with no zeros in the spatial frequency response function over the frequency domain of interest.

Abstract: An apparatus and method for the measuring the transverse dimensions of a hole such as in an oil well including a sonde on which an electro-acoustic transducer is mounted in an off centered position in relation to the axis of the sonde. This transducer has two opposite active faces so as to simultaneously transmit acoustic pulses in diametrically opposite directions from the sonde. When the sonde is centered in the hole, the transducer picks up the echoes retransmitted by the wall of the hole in the two directions, at different times. A recording is made of these times and preferably also of an indication of the amplitude of each of these echoes to obtain both a diameter measurement and an indication of the condition of the hole surface. Several transducers are provided, superposed and oriented along various diameters distributed around the axis of the sonde.

Abstract: A method and apparatus for enhancing the resolution of an induction logging tool at a desired depth of investigation comprising receiving an induction signal from the formation corresponding to the desired depth of investigation, receiving a second signal from the formation having no zeroes in the spatial frequency domain and filtering and combining the received signals to provide high frequency signal information from the second signal to augment and enhance the first signal. Additional corrections, such as for skin effect and shoulder effect are also made.

Abstract: An acoustic well logging method and apparatus utilizes a rare earth acoustic transducer to provide low frequency acoustic energy within the borehole, and characteristics of a subsurface geological formation may be obtained, such as the formation permeability by measuring values of the attenuation of the Stoneley waves produced by the rare earth acoustic transducer.

Abstract: A shielded solenoid for use in well logging is disclosed in which a cylindrical or solenoidal coil is provided in a support member. A shield is spirally wrapped about the wall of the support member and the coil. The resulting toroidally shaped shield has its individual turns cut so that no complete electrical path exists in each loop of the shield. Each loop of the coil is electrically connected to a ground ring. The shielded solenoid is capacitively shielded from the borehole environment. The shielding is effective because the shielding conductors are effectively transparent to TE electromagnetic fields generated by alternating current flow in the cylindrical coil and substantially eliminate TM electromagnetic fields generation by such current flow.This abstract of the disclosure is neither intended to define the scope of the invention, which is measured by the claims, nor is it intended to limit the invention in any way.

Abstract: A controlled implosive downhole seismic source having a substantially hollow closed vessel body adapted to be lowered in a borehole and means for selectively causing at least a portion of the vessel body to implode under pressure thereby producing seismic waves.

Abstract: In the representative embodiment of the new and improved apparatus disclosed herein, a downhole tool adapted to be coupled in a pipe string and positioned in a well bore is provided with one or more electrical devices cooperatively arranged to receive power from surface power sources or to transmit and/or receive control or data signals from surface equipment. Unique inner and outer coil assemblies arranged on ferrite cores are arranged on the downhole tool and a suspension cable for electromagnetically coupling the electrical devices to the surface equipment so that power and/or data or control signals can be transmitted between the downhole and surface equipment.

Abstract: The invention concerns a process for measuring the flow as a function of time of the several layers of a subterranean multilayer hydrocarbon-producing formation through which a well is drilled, and for determining the parameters of formation by comparison of trends in well behavior shown by actual measurements with trends in behavior established theoretically. The flow rate contributions of individual layers (1 to 5) are determined from cumulative measurements made above successive layers by a flowmeter (13) moved vertically within a wellbore. Experimental curves are derived that represent the relative variations in time of the flowrates of layers (.DELTA.q.sub.j) or groups of layers in the formation using flowrate measurement points obtained when a total flowrate variation (.DELTA.Q) has been imposed on the well at a given time between two given constant values.

Abstract: The invention relates to a tool for measuring pressure in the annular space lying between casing and the production string of an oil well. The tool comprises two sliding elements, with the first element being temporarily locked in a section of the string constituting a circulating valve and with the second element carrying a pressure sensor which receives the pressure reigning in the annular space via a duct and orifices of the circulating valve after they have been brought into register.

Abstract: A well-logging tool, for use within a well borehole for measuring a characteristic of a flowing fluid therein, is shown to include a housing and a spinner for measuring the flow rate of the fluid. The spinner is disposed within the housing. To divert the fluid into the housing, the housing carries a funnel having a wide end and a narrow end, for sealing the annulus between the well borehole and the housing and for directing the flowing fluid into the housing. The narrow end of the funnel abuts and is attached to the housing. A pump is employed for pumping fluids into an inflatable tubular ring attached to the wide end of the funnel to seal the edges of the funnel against the borehole wall.

Abstract: A method for determining a sonde error characteristic of an induction tool is disclosed. The method includes the step of measuring an electrical characteristic which may be the real or quadrature component of conductivity, at two or more different heights above the earth. The sonde error characteristic is determined as a function of a predetermined relationship between the desired sonde error characteristic and the measurements of that characteristic at two or more different heights above the earth. The method may be performed with the tool disposed substantially parallel to the earth. Alternatively, the tool may be disposed substantially perpendicularly to the earth.

Abstract: According to the method an acoustic transmitter/receiver tool is lowered in measured manner down a borehole. The tool possesses separate transducers for transmitting and receiving sound waves and includes at least one pair of spaced apart transmitter and receiver spacing. As it is lowered, the tool is caused to repetitively transmit sound waves and on each occasion the waveforms of the echoes received by the tool are recorded in relation to the spacing. Fractures are detected by processing portions of the waveforms which are representative of at least one of two different local effects corresponding to fractures, which effects are amplitude peaks due to a local increase in acoustic coupling, and criss-cross patterns due to mode conversion.

Abstract: A method for layered reservoirs without crossflow in order to estimate individual layer permeabilities and skin factors is disclosed. The method consists of two sequential drawdown tests. During these tests the wellbore pressure and the sandface flow must be measured simultaneously. The permeability and skin factor for each layer are estimated uniquely using measured wellbore pressure and sandface flow rate from these two drawdown tests. The method can be generalized straightforwardly to layered reservoirs with crossflow, and can also be used to estimate skin factors for each perforated interval in a single layer reservoir.

Abstract: In accordance with illustrative embodiments disclosed herein, a formation testing tool suspended in a well on a pipe string includes a valve actuator control system which responds to a command signal having a certain signature. The command signal is applied at the surface to the well annulus, and includes a series of two or more low level pressure pulses which are detected at the downhole tool, each pressure pulse having, for example, a certain peak value which lasts for a certain time. On detection of the command signal, a control system within the testing tool permits selective application of hydrostatic pressure which forces the valve actuator to shift from one position to another, thereby to open or close an associated valve element.

Abstract: A method for determining a characteristic of a subsurface geological formation enhances the vertical resolution of dual-detector measurements by utilizing a continuous calibration factor which is obtained from an environmentally compensated characteristic derived from at least two resolution-matched sensor signals, and from a resolution-matched sensor signal from the near-detector of the tool.

Abstract: A detector for detecting the acceleration, the velocity or the displacement of a point is described. The detector includes a light source, at least two photoelectric elements spaced apart from each other over a predetermined distance and a focusing optical system disposed between the light source and the photoelectric elements; the combination being particularly suited for use as an optical seismic detector for detecting and mapping an underground stratum structure.

Abstract: Using waveforms or travel time acquired by multitransmitter and/or borehole sonic tools, acoustic velocity (or slowness) is computed for compressional, shear, and Stoneley waves using direct phase determination (DPD), the slowness time coherence (STC) method, and multiple shot processing (MSP). There is a nonzero difference between transmitter and receiver delta-t's (slownesses) when the sonic tool is in the vicinity of a borehole feature, such as a fracture or a borehole enlargement. The amount of the difference, T/R delta-t, for compressional, shear and Stoneley waves depends on the size and nature of the fracture(s). It is possible to determine the height, width, and dip angle of the fracture when the T/R delta-t's are used in conjunction with other model data. It is also possible to distinguish between borehole enlargements and fractures with the method of this invention.

Abstract: A method for determining a characteristic of a subsurface geological formation enhances the vertical resolution of dual-detector measurements by utilizing a continuous calibration factor which is obtained from an environmentally compensated characteristic derived from at least two resolution-matched sensor signals, and from a resolution-matched sensor signal from the near-detector of the tool.

Abstract: A method and apparatus for sealing a well casing, when a length of production tubing is disposed within the well casing, utilizes a sealing means having a first diameter less than the diameter of the production tubing, and the sealing means is compressible to a second diameter which sealingly conforms to the diameter of the well casing, to prevent fluids disposed in the well casing below the sealing means from flowing through the well casing to above the sealing means. .Iadd.To support the sealing means when it has been sealingly conformed to the diameter of the well casing, the well bore apparatus of the invention further includes upper and lower sets of opposed reinforcing members which are mounted on the body of the well bore apparatus above and below the sealing means and operatively arranged to be respectively swung outwardly from the body to an extended position for supporting the upper and lower end portions of the sealing means against longitudinal movement in the well casing. .Iaddend.