Abstract: The invention concerns a method for determining the position, in a formation (1) containing at least one electrolytic liquid, of an interface (6) in relation to a bore hole (2). One stimulates at a first instant the interface (6) with an excitation signal, one detects at a second instant (t2) a response signal converted by electro-osmosis or electrokinetic coupling effect and, if appropriate, the exication signal after reflection at a third instant (t3). With the three instants and the propagation velocity of the signals, one calculates the distance between the interface (6) and the bore hole (2).

Abstract: A resistivity tool for investigating a wall of a borehole drilled with a non-conductive mud includes a tool body adapted to be incorporated in a logging-while-drilling tool assembly; a resistivity sensor disposed on the tool body, wherein the resistivity sensor comprises a sensor pad supporting a current injector electrode, a current return electrode, and an array of measurement electrodes, and a circuitry for controlling current injection from the current injector electrode and for measuring voltage difference between electrodes in the array of measurement electrodes, wherein the current injector electrode and the current return electrode are disposed near opposite ends of the sensor pad and the array of measurement electrodes is disposed between the current injector electrode and the current return electrode, wherein the sensor pad is constructed of an insulating material and includes a conductive shielding member, or wherein the sensor pad is constructed of a conducting material and includes insulating sec

Abstract: The invention refers to an axial antenna structure for use on a borehole wireline or while drilling logging tool. The antenna comprises an insulating medium and an electrical conductor disposed on the insulating medium. The electrical conductor is situated to have a magnetic dipole moment parallel to a longitudinal axis of the borehole logging apparatus. A tri-axial configuration combines the axial coil design and at least one transverse antenna structure substantially co-located with the axial antenna. The transverse antenna structure has a magnetic dipole moment orthogonal to the magnetic dipole moment of the axial antenna.

Abstract: A method is described for characterizing a subsurface formation with a logging instrument disposed in a borehole penetrating the formation. The logging instrument is equipped with at least a transmitter system and a receiver system. The method entails positioning the logging instrument within the borehole so that the transmitter system and receiver system are disposed in the vicinity of a formation boundary of interest and measuring the azimuthal orientation of the logging instrument. Electromagnetic energy is transmitted into the formation using the transmitter system and signals associated with the transmitted electromagnetic energy are measured using the receiver system. The method further entails determining the relative azimuth of the formation boundary, composing a symmetrized directional measurement using the measured signals and the determined relative boundary azimuth, and determining the relative dip of the formation boundary using the composed directional measurement.

Abstract: A method for evaluating formation fluids includes measuring a nuclear magnetic resonance property related to a total volume of the formation fluids, measuring a dielectric property related to an electromagnetic wave travel time, measuring a bulk density, and solving a set of linear response equations representing a reservoir fluid model to determine fractional fluid volumes from the nuclear magnetic resonance property, the dielectric property, and the bulk density.

Abstract: A well logging tool and method are disclosed comprising a conductive mandrel, an antenna array disposed around the conductive mandrel, wherein the antenna array comprises a plurality of antennas disposed on insulating supports and at least one contact spacer, the at least one contact spacer having at least one conductor channel having a contact assembly disposed therein, a sleeve disposed over the antenna array, wherein the sleeve includes at least one electrode assembly, the at least one electrode and the contact assembly adapted to provide a radially conductive path from an exterior of the well logging tool to the conductive mandrel and wherein the electrode assembly comprises a first conductor exposed to the exterior of the well logging tool and at least one second conductor conductively connected to the first conductor and exposed to an inner surface of the sleeve, wherein at least one of the first conductor or the second conductor being in sealed contact with the sleeve to prevent the passage of fluid th

Abstract: A porous geological formation contains electrolytic fluid. During the geophysical prospecting of the formation, a region of interest of the formation where the electrolytic fluid is found is stimulated with an excitation signal. The excitation signal corresponds to an energy of a first type. The excitation signal is converted in the region of interest into a response signal. The response signal corresponds to an energy of a second type. The response signal is detected. An electric polarisation is applied to the region of interest so as to strengthen the response signal relative to what it would be in the absence of polarisation. The electric polarisation comes about by means of a continuous or quasi-continuous polarising electric field. The polarising electric field is modulated in frequency with a frequency which is low relatively to the excitation frequency.

Abstract: A logging tool includes a tool body; a simple transmitter comprising a single antenna disposed on the tool body; four simple receivers, each comprising a single antenna, disposed on the tool body and spaced apart from the simple transmitter to form four arrays; and an electronic module for controlling operation of the four arrays, wherein the simple transmitter is configured to generate a magnetic field having a transverse component, wherein each of the four simple receivers is sensitive to the magnetic field generated by the simple transmitter, and at least one of the four simple receivers is sensitive to the transverse component of the magnetic field generated by the simple transmitter, and wherein the four arrays are configured to provide measurements at at least three depths of investigation.

Abstract: A composite shell adapted to cover a source or sensor, particularly for subsurface applications. The shell provides transparency to the passage of signals to or from the source or sensor. The shell is adapted with a uniform semi-conductive surface providing a path for electric currents flowing within a subsurface borehole to short near the source or sensor.

Abstract: An apparatus capable of moving a shiftable valve member into a closed position, the shiftable valve member mounted in a valve housing having a bore and being moveable between at least one open and at least one closed position relative to the bore, includes at least one elastically deformable member that extends at least partially around the circumference of the bore and is disposed at least partially in a cavity in the valve housing. Each elastically deformable member is elongated, has first and second ends and is connected to the shiftable valve member at one location and to the valve housing at at least one other location. Each elastically deformable member is torsionally loaded to provide biasing, closing force to the shiftable valve member to assist in moving the shiftable valve member into a closed position and retaining it in the closed position.

Abstract: An apparatus capable of moving a shiftable valve member into a closed position, the shiftable valve member mounted in a valve housing having a bore and being moveable between at least one open and at least one closed position relative to the bore, includes at least one elastically deformable member that extends at least partially around the circumference of the bore and is disposed at least partially in a cavity in the valve housing. Each elastically deformable member is elongated, has first and second ends and is connected to the shiftable valve member at one location and to the valve housing at at least one other location. Each elastically deformable member is torsionally loaded to provide biasing, closing force to the shiftable valve member to assist in moving the shiftable valve member into a closed position and retaining it in the closed position.

Abstract: An apparatus capable of retaining a shiftable valve member in an open position, the shiftable valve member mounted in a valve housing and being moveable between at least one open and at least one closed position relative to a longitudinal bore extending through the valve housing, includes a locking sleeve disposed in the valve housing. The locking sleeve is movable at least partially around the circumference of the bore from at least a first position to at least a second position. When the locking sleeve is disposed in the first position, the locking sleeve allows movement of the shiftable valve member between its open and closed positions. When the locking sleeve is disposed in the second position, the locking sleeve causes the shiftable valve member to be retained in an open position and prevents movement of the shiftable valve member into a closed position.