Abstract: Method for determining the composition of a homogeneous fluid, for example a petroleum effluent on flow, an emulsion consisting of water and oil, or a foam consisting of oil and gas. The attenuation and the phase shift of microwave beams that have traversed a fluid of unknown composition with paths of different lengths are measured (stage A). Two equations approaching the measured values are determined, the first equation giving a relation between the attenuation and the length of the path, the second equation giving a relation between the phase shift and the length of the path (stage C). Then the composition of the fluid is determined by comparing the two equations with pairs of equations stored in form of databases, each pair of equations corresponding to a fluid of known composition (stage D).

Abstract: Method for determining the composition of a homogeneous fluid, for example a petroleum effluent on flow, an emulsion consisting of water and oil, or a foam consisting of oil and gas.

Abstract: A process and device for measuring the velocity of flow of a fluid stream by measuring the difference between the respective traveltimes of acoustic pulses emitted by means of a generator (G) respectively between two points (PA, PB) spaced out along the fluid stream, according to whether they are propagated upstream or downstream in relation to the direction of flow, a difference that is indicative of the displacement velocity of the fluid stream. Measurement of this traveltime difference comprises using an acquisition unit (A) coupled to a processing unit (P) allowing determination of the frequency spectrum of each pulse and measurement of the phase lag affecting at least part of the frequency spectrum of each pulse, resulting from the traveltime thereof. Measurement of the velocity of flow of the fluid stream and of the resulting flow rate is very accurate. The process can be applied in chemical industries, chromatography, etc.

Abstract: Very low distortion hydrophone comprising at least one pair of sensitive elements (6 and 8) of piezoelectric type (for example and not limitatively), associated with at least one of the opposite flexible faces of a housing (1) formed by assembling cups (2 and 3) with rigid edges. The opposite faces of one of the discs, (6), are provided with electrodes over the total surface thereof. On the other hand, at least one of electrodes (9a and 9b) associated with the opposite faces of second disc (8) only covers one or more portions (an annular strip for example) of each of these faces in an external zone of each cup (2, 3) more subjected to nonlinear stresses. Electrodes (7 and 9) of the two sensitive discs (6 and 8) are interconnected so as to make the difference between the electric signals generated by the two discs in response to the pressures applied, with the effect, experimentally verified, that the distortion resulting from this layout, notably due to a second harmonic (2), is practically suppressed.

Abstract: The invention is an interferential refractometry method and device using fine measurement of the displacement of the fringes of an interference pattern between two light beams with one of the beams undergoing phase variations due to variations in the refractive index thereof. The method comprises application, to one of the two beams, of a relatively fast periodic phase modulation by a modulating signal. Displacement of the fringes resulting from the combined application of the two modulations is picked up by a photodetector and a measuring system evaluates the slow modulation by determining the frequency spectrum of the signal coming from the detect or and measuring the phase shift affecting the fundamental frequency of this frequency spectrum. The method may be applied to detection of variations in the composition of mixtures, for example in analytical or preparative chromatography.

Abstract: In order to restore a clock signal that has been used for coding digitized signals transmitted on a transmission channel, such as a line, the case when the received signals are distorted, the times (ti) when the signals go through their maxima (M) are detected with precision through an analysis of a series of samples (Ep) taken from the signals received during a time "window" (W) positioned with reference to a local clock. A device determines the amplitude differences between the successive samples and compares the difference configuration as obtained with predetermined standard configurations representative of forms that are acceptable for the maxima. In case when the difference configuration corresponds to no recognized standard configuration, the frequency of the local clock is changed so as to re-establish a sufficient similarity with a standard configuration.

Abstract: In a pipe containing a fluid wherein particles circulate, at least one detector is attached. The detector includes a cavity in fluid communication with the pipe by a vent whose section, at least at an opening for fluid communication with a pipe is of the same dimensions as that of the circulating particles. A periodic exciter such as a source of acoustical waves or a generator of the periodic motion piston type suitable for inducing alternate pressure variations in the fluid in the cavity is coupled with the cavity. The excitation frequency can be selected in keeping with a resonance frequency of the cavity. Signals representative of the pressure variations of the excited fluid, resulting from flowing of the particles past the opening of each vent are measured. Processing of the signals allows the velocity of the particles to be determined. Other parameters of the particles can be determined by means of two distinct detectors coupled with the pipe.

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: The present invention relates to a method and to a device for testing a partly conductive medium to determine a characteristic thereof. A signal generator generates a periodic excitation signal in a resonant circuit, including a coil which produces a magnetic field, which is coupled to the partially conductive medium. Eddy currents induced in the partially conductive medium cause the current flowing in the resonant circuit to vary. The amplitude of the envelope of the current flowing in the resonant circuit is measured and processed to determine the characteristic of the medium.

Abstract: The invention relates to the measurement of the difference between refractive indexes of two media, traversed by a light beam the beams produce an interference figure consisting of fringes having a displacement which is measured.According to the invention, the displacement of the fringes of the interference figure is detected with a photosensitive device and a phase modulation is performed on at least one of the beams and the modulation is controlled in order to obtain a movement of the fringes of the interference figure.

Abstract: A device for simplifying transmission of analog signals received from sensors to a remote station in accordance with the invention includes at least one local electronic module including in combination a modulator for oversampling each analog signal and converting each oversampled analog signal into lower resolution digital words and a transmitter for transmitting the lower resolution words as a bit stream on at least one first transmission channel; at least one synchronization element producing a clock signal allowing synchronization of each modulator with the remote station; and at least one reception module in the remote station including a receiver for receiving the transmitted lower resolution words as a bit stream and a digital filter, coupled to the receiver, for converting each received bit stream received into digital words of a higher resolution (typically 16 or 24 bit words. The invention is useful for transmission of seismic data.

Abstract: In order to measure for example the velocity of particles moving within various pipes or enclosures (1), such as catalyst balls circulating in continuous reforming plants, a channel (2) with a section suited to that of the particles, connected to a source of fluid of determined flow rate (4), opens therein and the pressure variations in this channel, resulting from the flow of the particles circulating past the end thereof, which modify the free flowing of the fluid towards the pipe, are measured. The particle velocity is notably determined through an auto-correlation of the signal translating the pressure variations by means of a processing system (6). Two fluid-fed channels (7, 8) may also open onto two different locations along the pipe and, through a crosscorrelation of the signals translating respectively the pressure variations, the velocity and the section of the circulating particles may for example be determined.

Abstract: Monitoring of an underground effluent deposit (2) and the exploration thereof are performed by installing various devices or user modules : reception arrays (Ri, Rj, Rk) such as geophones or hydrophones, condition sensors (C1, C2) , tools requiring electric power supply, etc, in various locations along one or several wells (1) drilled down into a formation, behind well casings or in the annular space between these casings and tubings, and by connecting these devices to a surface station (4), by means of a particularly simple and reliable multi-channel transmission unit. The surface station adapts the commands thereof according to the device to be controlled in return, of receiving all the signals they transmit whether analog or digital and coded, and adapts to several modes of allocation of the transmission channels. With such a system, long-duration monitoring operations may be carried out on a large scale under satisfactory economic conditions.

Abstract: A process for optimizing the transmission rates of digitized signals on transmission lines in multifunction cables, such as logging cables linking well tools to surface installations. The process includes digitising of the data to be transmitted and coding thereof through voltages selected from a set of multilevel coding voltages (2 to 32 for example), and widening towards high frequencies of the passband of each transmission line used, by combination with correcting circuits selected so that the transfer function of the corrected line is substantially that of a filter of the Bessel type, at least in a given frequency range on either side of a 3-dB cut-off frequency fc which depends on the number of coding voltages and on the amplification parameters. Using this process makes it possible to exceed very easily a total flow rate higher than one Mbits/s without increasing the transmission error rate.

Abstract: Modular device for the reception, the acquisition and the transmission, to a central control and recording unit, of signals picked up by a very large number of seismic acoustic receivers distributed along a streamer of great length under water in operation.The receivers in each one of the sections (Tk) of the streamer are arranged in several groups and the receivers (H1 to Hp) of a same group are connected with an acquisition unit (U1 to Um) located close to them. All the units of each section are connected through digitized command and data transmission lines (LOC,BD) with a common memory and a transmission management unit in an interconnection box (Bk) at one end of the streamer section. Transferring a great part of the electronic equipment into the streamer sections is very favorable for the balancing of the streamer in the water, for obtaining a good signal to noise ratio and it facilitates the development and the exploitation of the material.

Abstract: A reception system including a central core (5) formed of a traction cable (6) and a harness (7) of conducting wires. A fibrous or porous acoustic screen (8) made, for example, from a fibrous or porous material is formed around the core. Sensitive elements are arranged outside this screen, with discontinuous inner electrodes (9) connected to the different wires of the central harness (7), and a common outer electrode (13). A pipe made of a piezoelectric material (12) is formed therebetween. The whole is covered with a protective sheath (2). With such a multi-layered sensitive structure, the manufacturing process of the reception system can be simplified.

Abstract: A method and device for acquiring signals by amplifying, sampling and digitizing for permanently controlling the stability of the gain at each successive sampling cycle carried out on the signals as disclosed. A first digitizing of a non amplified signal sample and at least a second digitizing of an amplified signal sample is performed at each cycle. Each gain is measured by establishing a ratio between the values respectively obtained at the end of each second digitizing and of the first digitizing, and the amplifier gain is corrected if the gain of each gain actually applied to the acquired signal has deviated from a nominal value. The invention has an application to the digitizing of seismic signals.

Abstract: Method and device for the high-rate transmission of data between a multiplicity of acquisition apparatuses (Ai) and a central station to which they are connected by a common transmission channel (V1) for commands and by a high-rate transmission channel (V2) for data.A first clock signal (H1) serves for the transmission of the orders, the acquisition of the data and their storage in a memory (10). A second clock signal (H2) with a higher frequency non synchronous with the first one is used for reading the data stored by each acquisition apparatus. A determined time interval (or window) is assigned to each apparatus and the reading of each stored sample is activated by an order signal indicating the beginning of this window.Application to a seismic transmission system for example.

Abstract: A signal sensor automatically compensates for the variations of the static pressure of the medium in which it is placed. The signal sensor comprises one or two assemblies each formed of a piezoelectric sensitive element applied against one face of a flexible plate. The other face of the plate is shielded from the variations of the dynamic pressure to be measured by a material absorbing the vibrations but fairly flexible so as to transmit any variation of the ambient static pressure. This material which may be a porous foam or a fibrous substance impregnated with liquid, fills a tubular apertured sleeve.

Abstract: An acquisition device for digitizing highly dynamic signals. After amplification in a fixed gain amplifier, the signals are applied to a sample and hold unit, the output of which is connected to an analog-to-digital converter to which a variable reference voltage is applied. This reference voltage is available at the output of a multiplexer to the inputs of which voltages are applied derived from sub-divisions of a calibrated voltage. The choice of the reference voltage is effected by a logic assembly as a function of the comparisons made by comparators between the sampled voltage and the derived voltages. The digitized signals are represented by a digital word from the converter and a digital word of gain G from the logic assembly.