Total Sa

Elf Exploration Production

Total Se

Elf Aquitaine Production

Association Scientifique Pour La Geologie Et Ses Applications

Totalenergies Onetech

Pierre Thore

Christian Hubans

Jonathan Anthony Edgar

Pierre Bergey

Olivier Robbe

Antoine Mazuyer

Philippe Solans

A method for providing a calibrated rock-physics model of a subsoil. First, a geological model of the subsoil comprising a grid made of cells, associated with a rock-physics parameter is obtained. A group of cells forming a calibration body is selected in the grid. The calibration body corresponds to a region of the subsoil having substantially homogenous rock-physics parameter values. Finally, an adjustable constant parameter in a physical equation expressing a relationship between the petro-physical parameter and a petro-elastic parameter in the calibration body is calibrated so as to reduce a mismatch between the petro-elastic parameter estimated using the physical equation and a petro-elastic parameter value determined from inverted seismic data, the calibrated physical equation providing a calibrated rock-physics model of the subsoil in the calibration body.

Method for providing a calibrated rock-physics model of a subsoil

A computer implemented method for analyzing a reservoir grid modeling a reservoir geological formation is provided in which the reservoir grid corresponds to a 3D grid of cells associated to respective values of at least one geological property. The method includes obtaining a 4D seismic image of the reservoir geological formation. A skeleton of the 4D seismic image is calculated, and the skeleton extends between at least one origin and a plurality of extremities. Each point of the skeleton is associated to a value of the at least one geological property of the reservoir grid. Flow time values are calculated for a fluid flowing from the origin to the extremities along the skeleton, based on the at least one geological property values associated to the points of the skeleton. The reservoir grid is calculated based on the flow time values.

Method and system for analyzing a reservoir grid of a reservoir geological formation based on 4D seismic images

It is proposed a method which comprises providing a geomechanical model of the geological environment, measurements of a first geological attribute each performed at a respective first position of the geological environment, constraints on a second geological attribute related to a yield criterion and each assigned to a respective second position of the geological environment, and a geomechanical simulator. The method also comprises determining the stress field derivable from the data outputted by the geomechanical simulator taking as input the geomechanical model and an optimal set of one or more boundary conditions. This provides an improved solution for estimating in situ stress field of a geological environment.

Estimating in situ stress field

A method includes obtaining a first time series of a first well parameter from the first well and a second time series of a second well parameter from the second well, processing the first time series to obtain a processed first time series, filtering the second time series by removing dynamic variations from the second time series to obtain a filtered second time series representative of static variations of the second time series, and determining a correlation between the processed first time series and the filtered second time series at various time shifts between the processed first time series and the filtered second time series, and determining a maximal correlation coefficient and a time shift at maximal correlation between the processed first time series and the filtered second time series, the maximal correlation coefficient being representative of the connectivity between the first well and the second well.

Method for evaluating connectivity between a first well and a second well in a hydrocarbon production field and related system

A subsoil region is represented using a grid having columns of cells arranged in an array of horizontal positions. The cells of a column are delineated by geological layering of the subsoil region. The method, used for estimating elastic parameters in the subsoil region, comprises obtaining seismic traces and performing seismic inversion for the columns of cells. The seismic inversion for a column comprises selecting a set of elastic parameter values that minimizes a cost function regardless of statistical distribution of the elastic parameter values. The set of elastic parameter values is selected among a plurality of candidate sets of elastic parameter values each having values of elastic parameters for the cells of the column.

Method for estimating elastic parameters of subsoil

Disclosed is a method of characterizing a subsurface volume. The method comprises: extracting a geobody from seismic data arranged within a discretized volume comprising a plurality of cells, the geobody comprising a subset of the plurality of cells, each cell of the subset having one or more properties indicative of a particular fluid phase. The extraction of the geobody comprises: determining a propagation probability value for each cell indicative of the probability that a front will propagate through the cell; beginning from a source within the discretized volume, using the propagation probability value to calculate a traveltime for each cell, the travel time describing the time the front takes to travel from the source point to the cell; and using the traveltimes to extract the geobody from the seismic data.

Method of characterising a subsurface volume

Disclosed is a method for characterizing the evolution of a subsurface volume over time. The method comprises providing a first and second surveys of the reservoir with a first and second sets of seismic traces, performing an inversion to obtain estimates of changes having occurred between said first time and said second time in terms of at least one model parameter; wherein the subsurface volume is divided into regions according to a high order discrete classification attributed in accordance with the region's geologic characteristics, and said inversion is constrained per region of subsurface volume. The regions of subsurface volume may be geological layers.

Method of constraining an inversion in the characterisation of the evolution of a subsurface volume

Disclosed is a method for characterizing the evolution of a sub-surface volume. The method comprises providing a first and second surveys of the reservoir with a first and second sets of seismic traces, constructing an analytic filter operable to shift one or more seismic traces in dependence of a model parameter; and performing an inversion to obtain estimates of the model parameter such that the analytic filter aligns said first survey and said second survey. The analytic filter may be a plane wave destruction filter, and be such that the model parameter is a function of the analytic filter and is not a function of one or more of said second set of seismic traces.

Method for obtaining estimates of a model parameter so as to characterise the evolution of a subsurface volume

A 4D seismic technique, where a base seismic trace is measured at a first time in a region of the subsoil, and then a monitor seismic trace corresponding to the base seismic trace is measured at a second time. To interpret the 4D measurements, assumptions are made about the variation of elastic parameters in permeable layers at predefined positions in one direction between the first and the second time. Elastic parameters include the density (&#x3c1;) and the speed of propagation of the pressure waves (V) in the permeable layers. Numerical evaluation is performed for a capability of each assumption about the variation of elastic parameters to give an account of a change between the measured base seismic trace and the measured monitor seismic trace, and the variation of the elastic parameters is estimated in accordance with an assumption of optimum capability.

Method for estimating elastic parameters through inversion of 4D seismic measures

According to the invention, elastic parameters, including density, pressure wave propagation speed, and/or shear in pervious layers located in a dense underground area along an array of horizontal positions, are estimated by inverting 4D seismic data. Firstly, an estimate of variations in the elastic parameters in one or more starting positions of the array, which can be located on bored wells within the area in question, is obtained. Then, a propagation algorithm is used in order to gradually carry out the 4D data inversion on the basis of the starting positions. The inversion takes into account the previously estimated parameter variations. A spatial variation in the depth and/or the thickness of the pervious lavers in question can also be taken into account. Propagation is based on positions that are consecutively selected as providing optimal values for a cost function assessed in order to invert the 4D data.

Method for estimating elastic parameters by inverting 4D seismic measurements

A process for calculating a meshed description of a realization of an oil-bearing reservoir takes as its starting point a reference realization of the reservoir with a plurality of stratigraphic surfaces, a meshed reference description for the reference realization comprising a plurality of planes some of which describe the stratigraphic surfaces, each plane comprising a plurality of points, at least two stratigraphic surfaces of the realization corresponding to two stratigraphic surfaces of the reference realization. A plane of the meshed description representing one of the two stratigraphic surfaces of the realization is obtained by applying displacements to the points of the planes of the reference description, making it possible to pass from the reference stratigraphic surface to the stratigraphic surface in the realization. The other planes of the description are obtained thereafter by interpolation. The process makes it possible to preserve homology both of structure and of representation between the various realizations. It avoids the need to recalculate ex nihilo a meshed description of the reference.

Process for calculating meshed realizations of a reservoir

Method for determining at least one optimal trajectory between a point and a target situated in a medium and forming a centered volume, the position of each of whose points is known with geometrical uncertainties, characterized in that it consists in defining for the centered volume a gain which takes different values from the center to the peripheral boundary, and a zero value outside the centered volume; in determining a statistically significant number of instances of the positions of the centered volume as a function of the geometrical uncertainties which affect it, and in determining an aggregate gain at each point; in defining a volume of interest, site of the points with positive aggregate gains in the medium; in defining curvilinear trajectories between at least one entry point and at least one exit point of the said volume of interest; in integrating the aggregate gain along each of the said curvilinear trajectories in such a way as to obtain a profit associated with each trajectory, and in retaining all the trajectories whose profit is greater than a threshold.

Method for determining at least one optimal trajectory for reaching a fuzzy target situated in a medium starting from a point remote from the target

Method of producing impact point position probability maps for a well. It consists in defining a fixed, invariant target point chosen a priori on an initial location E0 of the surface S, discretizing the surface S with the aid of a grid composed of nodes and of grid cells, assigning at least one elementary geometrical uncertainty vector to each node of the grid of the surface S, determining a statistically significant number of occurrences of locations of the surface S as a function of the geometrical uncertainties affecting it, projecting the target point onto each occurrence of location of the surface so as to deduce a point of impact therefrom, transferring the set of impact points onto the location E0 of the surface S by allocating, to each of these points, surface co-ordinates identical to those which it had on the occurrence of location of the surface containing it.

Method of producing impact point position probability maps for a well

The method consists in using a first interpreted horizon (H.sub.0) extracted from a seismic block migrated with at least a first value of a velocity (V) known with an uncertainty (.DELTA.V), and is characterized in that it consists in performing the following steps:

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Pau, France

Pierre Thore