Abstract:
The transducer comprises for example a block (1) of sensitive elements such as piled piezoelectric disks held up by a stud bolt between two ferrules and a shell (8) all in one piece, that is arranged around the piling with a concave central part (8A) extended on either side by a solid cylindrical part (8 B, 8 C). Two sleeves are arranged at the two opposite ends of the transducer and elastic elements (14) for decoupling them in relation to the vibrating block (1) are interposed. A flexible housing (18) can be placed around the shell (8) so as to insulate from the outside environment the inner volume of the transducer that can be filled with a fluid such as oil. Connecting means allow the vibrating block to be connected to an exciting voltage source. The transducer can be used for the emission of vibrations at sea or in wells and notably petroleum or gas wells for example.
Abstract:
A process for installing seismic sensors inside a petroleum production well equipped with a cemented casing involves arranging the seismic sensors along an outer surface of the casing before being descended into a drilled well and cementing a ring-shaped space between the casing and the well so as to acoustically connect the sensors to geological formations. The sensors and transmission cables which link them to the surface are secured to centering devices guiding the descent of the casing or to the casing outer wall, possibly by means of a coating of damping material. The sensors may be inserted into sleeves secured outside the casing.
Abstract:
An injection molding installation includes a box-like mounting base 1 on which are disposed a molding press 2 and a pressure injection apparatus 3. The press 2 includes fixed opposite end plates 4 and 7 mounted directly on the base 1 and an intermediate movable plate 5 slidably bearing on the base via an adaptor wedge A. The injection apparatus includes a motor driven rotary screw conveyor 18 and a plastics material feed funnel 19, and is removably mounted on the base 1 via an interchangeable support rail 22 clamped by internal cross bars 25 to the base or to intermediate spacer inserts 26 mounted thereon. The use of the adaptor wedge and interchangeable support rails enables the accommodation and mounting of molding presses and injection apparatuses having different sizes and configurations on a common and thus standardized mounting base.
Abstract:
Acoustic wave transducer comprising a sensitive element subjected on one face to the pressure variations of an external medium and on the other face to the pressure prevailing in an inner cavity of the body of the transducer, associated with automatic regulation means whereby said cavity communicates either with the external medium or with a source of fluid at a pressure exceeding that of the external medium, depending on the pressure level in said cavity as compared to that of the external medium.
Abstract:
A VSP or reversed VSP type seismic prospecting method according to the invention allows disturbances contained in seismic recordings produced by tube waves propagating along wells and refracted in zones close to the surface to be minimized. The method disperses a gas under pressure, having preferably a high compressibility, capable of absorbing these tube waves. The gas may be generated by an explosive chemical reaction set off in situ, at a certain depth of the well (which may constitute the seismic wave source). The method has an application for seismic prospecting or drilling noise monitoring.
Abstract:
Hydrophone with two unsymmetrically connected sensitive elements. The hydrophone comprises a detection unit including a closed housing (1) delimited by two cups (2, 3) resting against each other, each one being provided with a flexible diaphragm (4) and at least two piezoelectric sensitive elements (6, 8) associated each with electrodes (7, 9), one outside the housing, the other inside the housing. The two sensitive elements are preferably different in size, notably with different diameters. Electrodes (7a, 9a) of the sensitive elements that are not in contact with cups (2, 3) are electrically interconnected and the electrodes in contact with cups (2, 3) are also electrically interconnected. Each detection unit is preferably included in a protective assembly (not shown). The hydrophone can be used for marine seismic monitoring or prospecting for example.
Abstract:
A vibration detector is disclosed. The vibration includes a ring (2) closed at its opposite ends by two ring ends (3, 4), that is externally covered with a sheath (11) made from an elastic material transparent to vibrations, two supporting plates (5) with a flexible central part (6) and a reinforced peripheral part (7) resting on the two ring ends. An inner cavity (8) between the two plates (5) is filled with liquid communicating through ports (10) and sheath (11) with the outside environment. Two sensitive elements (9) such as piezoelectric disks for example are fastened to the flexible central parts (6) on their faces of the interior of the cavity (8). The sensitive elements (9) are well protected from the outside environment and their sensitivity is not substantially influenced by variations in the static pressure. The invention has an application for detection of acoustic or seismic waves.
Abstract:
A textile backing with a decorative weft is manufactured by raising at least one bonding needle across the warp yarn lap of the textile backing, the bonding needle being used to form a locking mesh having a number of loops; retracting the needles under the textile backing; inserting a decorative weft at right angles to the warp yarns; simultaneously raising and shifting the needles and shifting the locking mesh yam in a circular arc movement using binding guides in order to twill the path of the bonding needle, thereby forming a locking mesh for retaining the decorative weft; displacing the binding guides in translation at a top dead center position for flattening the decorative weft yam against the needle; lowering the bonding needles, drawing the mesh-forming yarn, and creating a loop of locking mesh yarn which encloses the decorative weft; and re-shifting the guides in translation at bottom dead center position in preparation for a new cycle.
Abstract:
The mobile seismic system according to the invention is made up by interconnecting reception sections (T1) and of anchoring sections (T2), and possibly emission sections, the assembly being suspended in the well by means of an electro-carrying cable (3). The first sections (T1), which are filled with liquid, are delimited at least partly by a wall transparent to acoustic waves. They contain each one or several hydrophones and an electronic module of acquisition of the signals picked up. The second sections (T2) comprise a body provided with retractable anchoring means (13) and with motor means, either autonomous, or connected, by a hydraulic line running along the reception system, to common motor means located preferably in a lower section so as to be used as a ballast weight. The reception system may be continuous or made up of several parts connected to each other by electric or electro-hydraulic linking means. The system is suitable for seismic prospecting in wells for example.
Abstract:
Electric interconnecting cables fitted with sealed electric connectors resistant to pressure are most often used to connect electrically together various equipments (1) distant from one another and immersed in a conducting liquid such as may be encountered in wellbores. To avoid this relatively costly solution, a process is proposed, wherein the various equipments (1) are linked together through sealed and empty hydraulic pipes or cables (22), so as to form a common space insulated from the external environment, and the electric linking conductors (25) are passed inside the hydraulic cable circuit constituted thereby.