Institut Francais Du Pe'trole

Institut Francias Du Petrole

Sylvain Sarda

Bernard Bourbiaux

Chakib Bennis

Marie-Christine Cacas

Sophie Balaven

Emmanuel Manceau

Jean-Daniel Boissonnat

Luca Cosentino

Eric Pain

Rémy Basquet

Jean-Claude Sabathier

Laurent Jeannin

A method is disclosed for modelling low or high compressibility fluid flows in a multilayer porous medium crossed by a network of fractures of given geometry, unevenly distributed in the medium, some of the fractures communicating with one another. Each fractured layer is defined by means of a grid pattern comprising fracture grid cells centered on nodes either at the fracture intersections or at the fracture ends. Each node is associated with a matrix block including all the points closer thereto than to neighboring nodes, and the local flows between each fracture grid cell and the associated matrix volume are calculated in a pseudosteady state. A modelling equation whose form is similar to the diffusion equation solved in conventional cases (low compressibility fluids) allows accounting for the compressibility of the fluids. The direct flows between the fracture grid cells and the direct flows between the matrix volumes through the common edges of the grid cells are determined, and the interactions between the pressure and flow rate variations that can be observed in at least one well through the medium are simulated.

Method for modelling fluid flows in a multilayer porous medium crossed by an unevenly distributed fracture network

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 for modelling flows in a fractured medium crossed by a network of fluid conducting objects of definite geometry but not homogenizable on the scale of each grid cell of the model (large fractures, sub-seismic faults for example, very permeable sedimentary layers, etc.) which has an application in the evaluation of hydrocarbon reservoirs is disclosed. The method allows simulation fluid of flows in a fractured porous geologic medium of known structure that is discretized with a grid and modelled by considering that each elementary volume of the fractured geologic medium is an equivalent fracture medium and matrix medium on the scale of each cell between which fluid exchanges are determined. The method determines exchanges between the matrix medium and the fracture medium, and modeles the transmissivities of the various cells crossed by each conducting object, so that the resulting transmissivity corresponds to the direct transmissivity along each conducting object. Explicit modelling of these objects, which is prohibitive on the scale of a field because of the very large number of cells involved and of the numerical constraints, is therefore unnecessary.

Method for modelling flows in a fractured medium crossed by large fractures

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

A method is disclosed for modelling fluid flows in a fractured multilayer porous medium by accounting for the real geometry of the fracture network and the local exchanges between the porous matrix and the fractures at each node of the network, thus allowing simulation of the interactions between the pressure and flow rate variations in a well running across the medium. The method essentially comprises discretizing the fractured medium by means of a mesh pattern, with fracture meshes centered on nodes at the various intersections of the fractures with each node being associated with a matrix volume, and determination of the flows between each fracture mesh and the associated matrix volume in a pseudosteady state. The method can be applied in hydrocarbon production well testing.

Method for modelling fluid flows in a fractured multilayer porous medium and correlative interactions in a production well

A method of exploring a heterogeneous geological porous original medium, such as a reservoir crossed by an irregular network of fractures, by means of a transposed medium be equivalent to the original medium with respect to a determined type of physical transfer function known for the original medium. The method includes (a) analyzing the original medium to acquire data as to its physical characteristics; (b) forming an image of at least two dimensions of the original medium as an array of pixels, based on the acquired data; (c) associating with each pixel of the array an initial value for the physical transfer function, (d) assigning values for the physical transfer function at each pixel of the array, such as the minimum distance separating the pixel from the nearest fracture, by reference to values of the function assigned to neighboring pixels of the image, (e) determining a physical property of the transposed or equivalent medium by identifying a volume portion of the equivalent medium based on the physical transfer function for the corresponding volume portion of the original medium, and (f) physically exploring the original reservoir based on the determined physical property. The physical transfer function can represent variations between different parts of the original medium, for example distance or transmissivities or heat transfers, such as between a reservoir and a well crossing the reservoir, etc. The method can be applied to determine a transposed medium providing the same recovery of a fluid during a capillary imbibition process as the actual medium.

Method for simplifying the modeling of a geological porous medium

Method for determining the equivalent fracture permeability of a fracture network in a subsurface multi-layered medium from a known representation of this network. The equivalent fracture permeability of a fractured network in a subsurface multi-layered medium, is determined by discretizing with a specific procedure each fracture (F) of the fracture network in fracture elements (R) (such as rectangles for example) and defining nodes N representing interconnected fracture elements in each layer of the medium and determining fluid flows (steady-state flows e.g.) through the discretized network while imposing boundary pressure conditions and fluid transmissivities to each couple of neighboring nodes. The method allows for a systematic linking of fractured reservoir characterization models with dual-porosity simulators in order to create a more realistic modeling of a fractured subsurface geological structure. The method can be implemented for example in oil production by reservoir engineers for obtaining reliable flow predictions.

Growing community of inventors

Rueil-Malmaison, France

Sylvain Sarda