Reservoir modeling
Encyclopedia
In the oil and gas industry, reservoir modeling involves the construction of a computer model of a petroleum reservoir, for the purposes of improving estimation of reserves
and making decisions regarding the development of the field.
A reservoir model represents the physical space of the reservoir by an array of discrete cells, delineated by a grid which may be regular or irregular. The array of cells is usually three dimensional, although 1D and 2D models are sometimes used. Values for attributes such as porosity
, permeability and water saturation are associated with each cell. The value of each attribute is implicitly deemed to apply uniformly throughout the volume of the reservoir represented by the cell.
Sometimes a single "shared earth model" is used for both purposes. More commonly, a geological model is constructed at a relatively high (fine) resolution. A coarser grid for the reservoir simulation model is constructed, with perhaps two orders of magnitude fewer cells. Effective values of attributes for the simulation model are then derived from the geological model by a process of "upscaling". Alternatively, if no geological model exists, the attribute values for a simulation model may be determined by a process of sampling geological maps.
Uncertainty in the true values of the reservoir properties is sometimes investigated by constructing several different realizations
of the sets of attribute values. The behaviour of the resulting simulation models can then indicate the associated level of economic uncertainty.
The phrase "reservoir characterization" is sometimes used to refer to reservoir modeling activities up to the point when a simulation model is ready to simulate the flow of fluids.
Commercially available software is used in the construction, simulation and analysis of the reservoir models.
Oil reserves
The total estimated amount of oil in an oil reservoir, including both producible and non-producible oil, is called oil in place. However, because of reservoir characteristics and limitations in petroleum extraction technologies, only a fraction of this oil can be brought to the surface, and it is...
and making decisions regarding the development of the field.
A reservoir model represents the physical space of the reservoir by an array of discrete cells, delineated by a grid which may be regular or irregular. The array of cells is usually three dimensional, although 1D and 2D models are sometimes used. Values for attributes such as porosity
Porosity
Porosity or void fraction is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%...
, permeability and water saturation are associated with each cell. The value of each attribute is implicitly deemed to apply uniformly throughout the volume of the reservoir represented by the cell.
Types of reservoir model
Reservoir models typically fall into two categories:- Geological modelsGeologic modellingGeologic modelling or Geomodelling is the applied science of creating computerized representations of portions of the Earth's crust based on geophysical and geological observations made on and below the Earth surface. A Geomodel is the numerical equivalent of a three-dimensional geological map...
are created by geologistGeologistA geologist is a scientist who studies the solid and liquid matter that constitutes the Earth as well as the processes and history that has shaped it. Geologists usually engage in studying geology. Geologists, studying more of an applied science than a theoretical one, must approach Geology using...
s and geophysicists and aim to provide a static description of the reservoir, prior to production. - Reservoir simulationReservoir simulationReservoir simulation is an area of reservoir engineering in which computer models are used to predict the flow of fluids through porous media.-Uses:...
models are created by reservoir engineersReservoir engineeringReservoir engineering is a branch of petroleum engineering that applies scientific principles to the drainage problems arising during the development and production of oil and gas reservoirs so as to obtain a high economic recovery....
and use finite difference methods to simulate the flow of fluids within the reservoir, over its production lifetime.
Sometimes a single "shared earth model" is used for both purposes. More commonly, a geological model is constructed at a relatively high (fine) resolution. A coarser grid for the reservoir simulation model is constructed, with perhaps two orders of magnitude fewer cells. Effective values of attributes for the simulation model are then derived from the geological model by a process of "upscaling". Alternatively, if no geological model exists, the attribute values for a simulation model may be determined by a process of sampling geological maps.
Uncertainty in the true values of the reservoir properties is sometimes investigated by constructing several different realizations
Realization (probability)
In probability and statistics, a realization, or observed value, of a random variable is the value that is actually observed . The random variable itself should be thought of as the process how the observation comes about...
of the sets of attribute values. The behaviour of the resulting simulation models can then indicate the associated level of economic uncertainty.
The phrase "reservoir characterization" is sometimes used to refer to reservoir modeling activities up to the point when a simulation model is ready to simulate the flow of fluids.
Commercially available software is used in the construction, simulation and analysis of the reservoir models.
See also
- Extraction of petroleumExtraction of petroleumThe extraction of petroleum is the process by which usable petroleum is extracted and removed from the earth.-Locating the oil field:Geologists use seismic surveys to search for geological structures that may form oil reservoirs...
- Petroleum engineeringPetroleum engineeringPetroleum engineering is an engineering discipline concerned with the activities related to the production of hydrocarbons, which can be either crude oil or natural gas. Subsurface activities are deemed to fall within the upstream sector of the oil and gas industry, which are the activities of...
- Computer simulationComputer simulationA computer simulation, a computer model, or a computational model is a computer program, or network of computers, that attempts to simulate an abstract model of a particular system...
- Seismic to simulationSeismic to simulationSeismic to Simulation is the process and associated techniques used to develop highly accurate static and dynamic 3D models of hydrocarbon reservoirs for use in predicting future production, placing additional wells, and evaluating alternative reservoir management scenarios...