Institut Francais Du Pe'trole

Other

Gaz De France-service National

Jean-Pierre Deflandre

Christian Grouffal

Jean-Paul Sarda

Guy Grard

Philippe Perreau

Jean-François Therond

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

A method for automatic analysis of signals acquired by one or more elastic or acoustic wave pickups to automatically locate with high precision, at least one significant instant such as the time of first arrival on each pickup (t ) and/or the end time (t ) of these signals. The method comprises determining the pseudoperiod corresponding to the inverse of the dominant frequency of the frequency spectrum of each acquired signal, coding each acquired signal so as to form a binary coded signal in reference to a first threshold value depending on the acquired signal, forming for each of them an integral signal by stacking of the binary coded signal on a sliding window in order to determine a second threshold value, and positioning the significant instant sought (t , t ) on each acquired signal in reference to an instant where the corresponding integral signal reaches this second threshold value.

Method of analyzing acquired signals for automatic location thereon of at least one significant instant

The invention is a method for facilitating discrimination and identification of seismic or microseismic events by means of permanent pickups in an underground zone under development. The method comprises permanent installation of, in one or more wells, elastic wave receivers, geophones and hydrophones leaving the wells clear for development of the zone, at least one reference pickup with direct acoustic coupling with the technical zone development equipment (pickup pressed against a production string for example) for detection of events directly connected with the operation of the wells (valve opening and closure, etc.), acquisition of the signals coming from the various receivers and from each reference pickup in response to the waves received, and comparative analysis of the signals associated with the receivers and with the reference pickup(s), in order to classify the records into different families according to whether the events in the underground zone are independent of the events detected by each reference pickup or depend directly or indirectly thereon, and for each family, application of specific processings. The method can be used for long-term monitoring of fluid production of storage reservoirs, such as hydrocarbons, various waste products, geothermics, etc.

Method for seismic monitoring of an underground zone under development

Device for carrying out tests on materials such as rock samples for example, on which triaxial stresses are exerted. The device comprises an extended body with a central cavity where a first part (6) of a sonic sonde, a sole piece (9) carrying a cubic sample (12) for example, jacks (13) which are introduced along the lateral faces of the sample by connecting them with channels (25) supplying fluid under pressure are successively placed. A centering piece (27) containing a box (26) for another part (28) of the sonic sonde and elements (31, 32) forming a cover are placed above. A piston (35) allows to apply stresses to the sample by means of the box (26). Lateral sensors (22) pick up the displacements of the sample. Application to the examination of rocks taken from a subterranean formation for example.

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Ermont, France

Jean-Pierre Deflandre