Institut Francais Du Pe'trole

Ifp Energies Nouvelles

Institute Francais Du Petrole

Chakib Bennis

Houman Borouchaki

Abdallah Benali

Sylvain Sarda

Patrick Lemonnier

Sophie Balaven

Longmin Ran

Nicolas Flandrin

Frédéric Roggero

Jean-Marc Daniel

Isabelle Faille

Roland Masson

Jean-Francois Lecomte

William Sassi

Jean-François Rainaud

Bertrand Moraisin

Jean-Daniel Boissonnat

Eric Pain

Thibaud Mouton

Frederic Roggero

Christophe Delage

Brahim Yahiaoui

Mathieu Poudret

Lionel Ladouari

The invention is a method for exploiting a subterranean medium, according to an exploitation scheme defined on a representation of the medium based on a two-dimensional grid representing the subterranean medium. The quality of the mesh cells of the grid is optimized by displacing the nodes of the grid by a procedure for minimizing the deformation of the grid by generating a reference grid; imposing a displacement of at least one node, termed a rigid node, of the reference grid on a corresponding node in the grid to be optimized; and constructing an optimized two-dimensional grid by displacement of the other nodes of the reference grid, while minimizing the displacement field of the nodes.

Method for exploitation of a subterranean medium in accordance with an exploitation scheme defined by an optimized representation

Process for constructing a volume mesh of a subsurface formation comprising at least one sedimentary layer traversed by at least one fault. On the basis of a representation in a closed domain of the geometry of the horizons and of the faults in a parametric space before deformation and rupture, the bounds of the blocks delimited by the faults, the horizons and the boundaries of the domain are projected onto a reference surface. Next a surface mesh is constructed constrained by the projections thus obtained on the reference surface. At each node of the surface mesh, a vertical polygonal line passing through this node is defined. Next a volume mesh is constructed by vertical extrusion of the surface mesh along the polygonal lines. Application in particular to exploration and to exploitation of oilfields.

Process for constructing a volume mesh for modeling geological structures

Method of constructing a geological for setting a depositional position of a stratigraphic unit. A depositional position of the stratigraphic unit is set with respect to a reference surface, to define a depositional space. The stratigraphic unit in depositional position is then calibrated to superimpose it on the initial stratigraphic unit. The wells are then positioned in this depositional space. A regular Cartesian grid is superimposed on the stratigraphic unit with a depositional position which is filled with property values characterizing the underground formation modelled by a geostatistical simulation. The values assigned to the cells of the grid are transferred to the cells of the stratigraphic mesh.

Method of constructing a geological model comprising setting a depositional position of stratigraphic units

A method having application for petroleum exploration or geological storage of generating a mesh of a faulted underground medium, comprising generating a hex-dominant mesh from faults and horizons in a form of a 3D triangulated surfaces. Each 3D triangulated surface is converted to a 2D triangulated surface onto which the faults are projected by an isometric unfolding technique. A regular two-dimensional grid pattern is generated for each 2D triangulated surface. The faults are accounted for by deforming quadrilaterals of the grid pattern intersected by projected faults. The deformed regular grid pattern is then converted to a 3D gridded surface and each quadrilateral which is crossed by a fault is converted into two triangles at a level of a diagonal. Finally, after iterating for all the 3D triangulated surfaces, the mesh is generated by creating links between the nodes of neighboring three-dimensional gridded surfaces with respect to the faults.

Method of generating a hex-dominant mesh of a faulted underground medium

A method for generating a mesh of a subterranean medium comprising at least one sedimentary layer crossed by at least one fault. The at least one layer is delimited vertically by two geological horizons discretized by two triangulated three-dimensional surfaces. For each horizon, a three-dimensional gridded surface is constructed by means of isometric unfolding accounting for the presence of the fault. Next, the mesh of the subterranean medium is generated by generating cells by creating links between the three-dimensional gridded surfaces. To do this, nodes of the first gridded surface that are situated on one side of the fault which differs from the side of a node of the second gridded surface having the same coordinates i, j are detected. Each non-detected node is joined with a node of the second gridded surface having the same coordinates i, j, and each detected node is joined with the fault by considering a direction of a neighboring node. Finally, the cells having at least two vertices in common are regularized.

Method for generating a hex-dominant mesh of a geometrically complex basin

This method for evaluating fluid flows in a heterogeneous medium, uses a hybrid grid constructed from a CPG type structured grid and from a radial grid. The first stage includes locally deforming a CPG type grid into a non-uniform Cartesian grid. These local grid cell deformations correspond to the change from a 'CPG' frame to a 'Cartesian' frame defined by the deformation. These deformations are then quantified, by a deformation function &#x3c6;, and applied to the radial grid so as to shift to the &#x201c;Cartesian&#x201d; frame. The second stage includes locally correcting the definition of this deformation function around the radial grid, so that the radial grid, in the &#x201c;Cartesian&#x201d; frame, keeps its geometrical characteristics. A hybrid grid is then generated in the &#x201c;Cartesian&#x201d; frame from the two grids thus deformed. Finally, this hybrid grid is deformed to return to the &#x201c;CPG&#x201d; frame, using the inverse of deformation function &#x3c6;.

Method for constructing a hybrid grid from a CPG type grid

A method for evaluating fluid flows within a heterogeneous formation, crossed by one or more geometric discontinuities, comprising generating a hybrid grid from a CPG type grid and from structured grids having application, for example, in simulation of hydrocarbon reservoirs. The first stage locally deforms a CPG type grid into a non-uniform Cartesian grid. These local grid cell deformations correspond to the change from a so-called 'CPG' frame of reference to a so-called 'Cartesian' frame of reference defined by the deformation. These deformations are then quantified and applied to the structured grids so as to shift to the &#x201c;Cartesian&#x201d; frame. A hybrid grid is then generated in the &#x201c;Cartesian&#x201d; frame from the two thus deformed grids. Finally, the hybrid grid is deformed to return to the &#x201c;CPG&#x201d; frame, prior to improving the grid quality, by optimization under quality control in the numerical scheme sense.

Method for simulating fluid flows within a medium discretized by a hybrid grid

A method, having application for hydrocarbon reservoir simulation, generates a hybrid grid, in order to carry out simulations in accordance with a defined numerical scheme, in three dimensions in a numerical scheme, of a heterogeneous formation crossed by at least one geometric discontinuity such as, an underground formation where at least one well has been drilled, or a fractured formation, by combining structured grids and unstructured grids. The hybrid grid includes a first structured grid for gridding the heterogeneous medium with second structured grids for gridding a zone around each discontinuity. A cavity of minimum size is automatically generated, with cells of the transition grid being an intermediate size between the size of the cells of the first grid and the size of the cells of the second grids.

Method of generating a conforming hybrid grid in three dimensions of a heterogeneous formation crossed by one or more geometric discontinuities in order to carry out simulations

A method for simulating flows in reservoirs, such as hydrocarbons, by means of chimera type grid which fluid generates a chimera grid made up of a set of elementary grids for accounting for characteristics of the flows and of the geometry (e.g., radial grid in the well zone and CPG grid for the reservoir) so that their union covers the entire simulation domain and that there is a minimum overlap between two neighboring elementary grids. Interpolation parameters allowing connection of the flows calculated on the grid to the flows calculated on the neighboring grids are then determined on the border of each elementary grid. Finally, flows are simulated within the reservoir and the well, and the variables describing the flow on the border of the overlap zones are interpolated using the interpolation parameters.

Method for simulating fluid flows within a reservoir by means of a chimera type discretization

A method of generating a hybrid grid of a heterogeneous formation crossed by one or more geometric discontinuities such as, for example, an underground formation where one or more wells have been drilled, or a fractured formation, by combining structured grids and non-structured grids in order to carry out simulations in accordance with a defined numerical pattern is disclosed. Hybrid gridding is performed by associating a first structured grid (G) for gridding of the heterogeneous medium considering discontinuities thereof with second structured, radial type grids (G) for gridding of a zone around each pipe or well, which allows better consideration of constraints linked with flows in the zone. In order to connect the first grid of the medium and the second well grids, non-structured transition grids (G) are interposed there between. A power diagram technique is used, which is particularly advantageous in that it allows appropriate connection of non-regular structured grids. An application is hydrocarbon reservoir simulation.

Method of generating a grid on a heterogenous formation crossed by one or more geometric discontinuities in order to carry out simulations

A method of generating a hybrid grid allowing modelling of a heterogeneous formation crossed by one or more pipes such as, for example, an underground formation where one or more wells have been drilled, in order to form a representative model, for example of fluid flows in the formation in accordance with a defined numerical pattern is disclosed. The method comprises associating a first structured grid for gridding of the heterogeneous medium regarding discontinuities thereof with a second structured, radial type grid for gridding of a zone around each pipe or well, which allows better constraints linked with flows in the zone, and transition of non-structured grids that are interposed between the first grid and each second well grid. Various grids are combined, each with its own formation, representation and exploration methods, structured grids which are advantageous in facilitating control and comprehension of the reservoir images formed and more flexible non-structured grids for gridding of complex zones. An application is simulation of hydrocarbon reservoirs.

Method of generating a hybrid grid allowing modelling of a heterogeneous formation crossed by one or more wells

The invention is a method applicable to a geologic structure, such as an oil bearing reservoir, defined from available data acquired either through measurements or through analyses and interpretations of seismic data or loggings performed in wells. The invention comprises previous modeling of the boundaries (zone edges, discontinuities or faults for example) by of triangulated surfaces enveloping as far as possible these boundaries and splitting up of the zone studied into blocks having at most six faces, whose faces correspond to discontinuities or main faults of the zone previously triangulated. Each block is thereafter subdivided into a set of elementary cells necessary for modeling the zone by finite elements or differences, by performing a gridding of each of the faces of the block by interpolation from the edges thereof so as to obtain a grid, followed by populating each block with nodes in the thickness thereof, by interpolation from the nodes of the various grids formed on the various faces, these operations being accompanied by particular homogenization procedures in order to readjust the size of the cells within each block according to predetermined rules. The gridded blocks are thereafter reassembled.

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Rueil-Malmaison, France

Chakib Bennis