Boots – shoes – and leggings
Patent
1995-05-19
1997-06-10
McElheny, Jr., Donald E.
Boots, shoes, and leggings
G06F 1900
Patent
active
056382693
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of seismic trace analysis for extracting therefrom geologic information relative to an underground formation such as an oil reservoir.
2. Description of the Prior Art
Statistical calibration techniques applied to seismic traces in order to extract therefrom geologic parameters at the level of a reservoir have already been described by Doyen, 1988, Porosity from seismic data: A Geostatistical Approach, Geophysics, 53, No. 10, 1263-1275, and by Fournier and Derain, 1992, Seismic Data Integration in Reservoir Simulations through a Multivariate Statistical Calibration Approach, 62nd Ann. Intern. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 95-98.
The calibration techniques used must be able to be easily adapted in case several geologic and seismic parameters are considered (multivariable aspect) and also to account for possibly non linear relations between the geologic and the seismic parameters. These techniques must not be limited by too many underlying probabilistic hypotheses, and they also must provide a proven quantification of the uncertainties linked to the values predicted by the calibration operation.
The known techniques for the geologic calibration of seismic data do not always fulfil these objectives.
SUMMARY OF THE INVENTION
The method according to the invention allows to bring together data which have been obtained through the seismic exploration of the formation and geological data resulting from measurements obtained by using measuring sondes into one or several wellbores crossing the reservoir zone. The method therefore utilizes a statistical calibration between the geologic parameters at the level of the reservoir and the characteristics of the seismic measurements obtained in the neighborhood of the wells. The main purpose of this statistical calibration is to establish an empirical relation between the seismic characteristics and the geologic properties of the reservoir at the level of the wells, a relation which is thereafter applied to the seismic traces far from the wells in order to assess the geologic characteristics of the reservoir.
The object of the method according to the invention is thus to improve knowledge of the reservoir between the wells from surface seismic data, which often display a much higher spatial coverage density than that of the wells.
The results obtained are useful in the early stages of the reservoir life when looking for the best sites for drilling wells (assessment phase or development phase beginning). At a later stage, the results are also useful to impose constraints on the reservoir model which has been established to represent the reservoir formation in question.
The method according to the invention allows, by respecting the requirements defined above, to predict (by carrying out an estimation, or by carrying out and a simulation in order to represent their uncertainties) geologic parameters of an underground formation such as an oil reservoir, from geologic information obtained through measurings or analyses performed in one or several wellbores crossing the formation and from a collection of seismic traces. This collection is obtained through the direct seismic exploration of the formation or it may consist of seismic traces calculated from data obtained in the wells for example. It particularly comprises a set of traces consisting of real traces obtained in the immediate neighbourhood of the wells (adjacent traces) or of calculated traces also corresponding to this neighbourhood. The calibration population defined hereafter is selected from this set of traces.
The method comprises the following stages: an analysis interval (in time or in depth) is defined on the seismic traces at the level of the underground formation, compatible with the geometric configuration of the formation, the seismic trace portions are characterized, within this analysis interval, by a set of p attributes, a certain number q of geologic parameters is deduced from said availab
REFERENCES:
patent: 4293309 (1981-10-01), Miller
patent: 4817062 (1989-03-01), De Buyl et al.
patent: 4926394 (1990-05-01), Doyen
P.M. Doyen, "Porosity from seismic data: A geostatistical approach", Geophysics, vol. 53, No. 10, Oct. 1988, pp. 1263-1275.
Fournier Frederique
Joseph Caroline
Institut Francais du Pe'trole
McElheny Jr. Donald E.
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