Institut Francais Du Pe'trole

Christian Grouffal

Joseph Rialan

Gerard Thierry

Jean-Pierre Deflandre

Renate Bary

Van Bui-Tran

Gérard Thierry

Jean-François Therond

An method of synchronizing a signal coming from at least one sensor positioned on an engine with a periodic event of the engine such as the crankshaft rotation is disclosed having application for engine control. A crankshaft rotation signal indicative of a reference time (TR), with which the engine signal(s) is to be synchronized, is acquired. The effective time difference (D) between the reference time and the time that is the closest to each temporally acquired engine signal is measured. Then the coefficients of a fractional digital compensation filter (FSDF) for compensating for the fractional part (d) of the measured effective time difference are determined. Finally, this digital compensation filter is applied to each temporally sampled engine signal, allowing obtaining of a series of digitized samples resealed from reference time (TR) for each engine signal.

Resynchronization of temporally acquired engine signals

A method for automatic classification, according to various selection criteria, of seismic or microseismic events picked up by seismic receivers coupled with an underground formation under development, according to whether the events are purely of microseismic nature or depend, on any account, on artifacts related to the outer environment or to formation development or monitoring activities, and for selection of the significant parts of traces for the purpose of analysis. The method has an application for monitoring of production or storage reservoirs under development.

Method intended for detection and automatic classification, according to various selection criteria, of seismic events in an underground formation

The invention pertains to transmission to a remote station, by means of transmission channels (generally radio transmission channels), of seismic data acquired by a data collection equipment comprising a plurality of acquisition units, each being suited to acquire, to store and preferably to compress the data to be transmitted. The invention comprises ordered storage, in a high-capacity memory (flash type memory for example) of each acquisition unit (Ai), of data obtained during successive emission-reception cycles (acquired and possibly preprocessed seismic data) so as to form a stream of stored data to be transmitted, and progressive transfer of the stored data stream from each acquisition unit to the remote station by means of the transmission channel, by reading each storage memory, with a time lag in relation to the time of their storage depending on the transmission rate of each transmission channel and on the transmission mode selected with preferably, if sending of the data of a cycle is delayed, sending of at least partial data, compressed or not, for quality control purposes. The data transmitted are reconstituted at the remote station. The method can be used for large-scale seismic data transmission.

Method and system for transmitting seismic data to a remote collection

The invention relates to a two-phase method of transmitting, to a central station (CS), seismic signals received by seismic receivers (R) and picked up by collecting units (A) disposed in the field. In the first phase, a compression is applied to each seismic trace, the ratio of which is adapted to the duration of a transmission window placed in the time intervals between successive seismic transmission-reception cycles, as well as to the rate of the transmission route used. The compressed trace as a whole is thus transmitted, allowing an operator at central station (CS) to check qualitatively that recording took place correctly in each collecting unit (A) even though he does not have the exact trace available. In the second phase, at the end of the current seismic session for example, the seismic traces are reconstituted in the central station with the necessary accuracy, either by complete transmission of the data preferably after prior compression, or, in certain cases, by transmission of residues eliminated in the first phase for the requirements of the first transmission.

Method of transmitting compressed seismic data

Seismic data acquisition devices (BA) distributed in an exploration zone are divided into n groups (GA1 to GAn) and, therein, into sub-groups having each a specific frequency for communicating with a concentration unit (Ck) which is connected to a central station (1) through Hertzian channels or cables or optical fibers. Acquisition devices in the various subgroups communicate simultaneously with the corresponding concentration unit (Ck) during predetermined emission windows. The concentration unit collects the signals received from the acquisition devices to transmit them in series to station (1). The acquisition devices are adapted for delaying their own emission window according to the rank which has been previously assigned thereto within the respective subgroups thereof.

Seismic transmission method and system utilizing concentration units

The arrangement in the field of seismic emission-reception system changes as it progrsses along the profile explored, which modifies the respective distances between the source of seismic signals (S) and each of the siesmic receivers (Ri). In order to take account thereof, each of the acquisition boxes (Bi) used in the field for amplifying, digitizing and storing the siesmic signals received during each emission-reception cycle (or possibly a central station) is provided with a processor for determining automatically the gain to be assigned to the various amplifiers from all of the signals acquired and with selection rules taking into account the level of the signals and their evolution observed over several successive emission-reception cycles. The invention has an application in decentralized automatic control of acquisition devices.

Seismic signal acquisition method and device

A method and an apparatus are applied to the seismic data received by receivers (Ri) distributed in the field and collected by acquisition boxes (Bi), in order to be transmitted to a central control and recording station (P), for example through hertzian channels. Digital words by adding to each N1-bit digitized signal sample, in each acquisition box, a n-bit coding suffix sufficient for detecting and correcting any transmission-related error. In order to eliminate the effect of long interferences, the method also comprises arranging the words in blocks, interleaving the words of each block at the time of the transmission, and forming digital symbols. A complementary sequence for reverse interlacing, deblocking and correcting possible errors brings the digital samples back to the original state thereof.

Seismic transmission method and device for a very low error rate

Method and device for simplifying the localization of a subsurface zone

A digitalization assembly of the over-sampling type includes an analog to digital converter (2) producing at a frequency F=kf small-format p samples and a digital filter (3) which, through the summation of a certain number n of over-samples, produces validated larger P-format samples at the frequency f, at instants fixed by a clock. In order to readjust the sampling instants in relation to an outside event which can occur at any time, a temporary memory store (5) is inserted between the converter (2) and the filter (3) and, according to the instant of arrival of this event, the appropriate samples to be sent towards the filter for their summation are selected.

Growing community of inventors

Rueil-Malmaison, France

Christian Grouffal