Abstract:
Methods and systems are provided for modeling an aspect of a hydrocarbon-containing reservoir by constructing a first factor graph having variables and factors that describe the aspect of the hydrocarbon-containing reservoir. The first factor graph is converted to a tree-structured graph that does not have any cycle or loops. The tree-structured graph is converted to a second factor graph that does not contain any cycles or loops, wherein the second factor graph has variables and factors that describe the aspect of the hydrocarbon-containing reservoir. A query on the second factor graph is carried out involving message passing operations that perform probabilistic inference on the second factor graph with regard to the aspect of the hydrocarbon-containing reservoir that is modeled by the second factor graph.
Abstract:
A method for performing operations of an oilfield is described. The method involves selectively coupling oilfield simulators according to a predefined configuration, each oilfield simulator modeling at least a portion of the oilfield, a first oilfield simulator receives an oilfield control parameter as an input, identifying an uncertainty parameter associated with probable values each corresponding to a weighted probability, a second oilfield simulator receives the uncertainty parameter as an input, modeling the operations of the oilfield to generate an estimated performance by selectively communicating between the oilfield simulators, the operations of the oilfield are modeled with a predetermined value of the oilfield control parameter and at least one of the probable values of the uncertainty parameter; and identifying an optimal value of the oilfield control parameter based on the estimated performance.
Abstract:
A method is disclosed for performing optimal gridding in reservoir simulation, the method comprising: establishing an optimal coarse grid proxy that can replace all or parts of a fine grid with a coarse grid while preserving an accuracy of a predefined simulation model output, the step of establishing an optimal coarse grid proxy including finding, by using an optimizer, a best fit of a coarse grid output to the output of a training set.
Abstract:
A tool is provided for measuring the angles of inclination and rotation of the tool itself, especially for use in a borehole. The tool preferably comprises an electrically nonconductive cylindrical chamber containing a conductive fluid and a nonconductive fluid which together fill the chamber; at least two wires oriented parallel to the longitudinal axis of the chamber and located about the circumference of the chamber at other than 180 degrees apart from each other, such that the surface interface between the conductive and nonconductive fluids may be defined by a point along each of the two wires along with a third point on the surface; and electrical means attached to the wires for sensing an electrical characteristic of the wires corresponding to the points along the wires defined by the fluid interface; and means for using the sensed electrical characteristics of the wires, a knowledge of the chamber radius, and a knowledge of the third point, and determining therefrom an index of inclination of said chamber. Preferably, the means for using the sensed electrical characteristics to determine an index of inclination also uses the sensed electrical characteristics of the wire and a knowledge of the third point to provide an index of rotation of the chamber. The electrical characteristics are typically resistance values which can be determined by injecting current into the wires and determining a resulting voltage.
Abstract:
A system for automatically optimizing a Field Development Plan (FDP) for an oil or gas field uses a fast analytic reservoir simulator to dynamically model oil or gas production from the entire reservoir over time in an accurate and rapid manner. An objective function defining a Figure of Merit (FoM) for candidate FDPs is maximized, using an optimization algorithm, to determine an optimized FDP in light of physical, engineering, operational, legal and engineering constraints. The objective function for the Figure of Merit, e.g., net present value (NPV) or total production for a given period of time, relies on a production forecast from the fast analytic reservoir simulator for the entire FDP.
Abstract:
A method for optimizing expensive functions with expensive nonlinear constraints. The method includes selecting sample data for evaluating an expensive function of a simulation, generating a function proxy model for the expensive function and a constraint proxy model for an expensive nonlinear constraint of the expensive function using an approximation scheme, calculating a first solution point for the simulation using the proxy models, and evaluating the expensive function at the first solution point using the sample data. When the expensive function and the proxy models do not converge at the first solution point, the method further includes adding the first solution point to the sample data for updating the proxy models. The method further includes repeating the calculation and evaluation of solution points until the expensive function and the proxy models converge and, following convergence, identifying an optimal solution of the function proxy model and the constraint proxy model.
Abstract:
A method of determining a selection of well measurements and/or their respective control parameters is described based on a global target having predetermined sensitivities to a multitude of uncertainties associated with input variables to a model including the step of ranking measurements and control parameters in accordance with their capability to reduce the uncertainties of input variables identified as most sensitive input variables through simulations using the model or a reduced variant of the model.
Abstract:
A hybrid evolutionary algorithm (“HEA”) technique is described for automatically calculating well and drainage locations in a field. The technique includes planning a set of wells on a static reservoir model using an automated well planner tool that designs realistic wells that satisfy drilling and construction constraints. A subset of these locations is then selected based on dynamic flow simulation using a cost function that maximizes recovery or economic benefit. In particular, a large population of candidate targets, drain holes and trajectories is initially created using fast calculation analysis tools of cost and value, and as the workflow proceeds, the population size is reduced in each successive operation, thereby facilitating use of increasingly sophisticated calculation analysis tools for economic valuation of the reservoir while reducing overall time required to obtain the result. In the final operation, only a small number of full reservoir simulations are required for the most promising FDPs.
Abstract:
A method for optimizing fracture treatments includes interpreting a nominal pump schedule corresponding to a nominal value for each fracture control parameter. The method further includes interpreting environmental variables, and interpreting probability distributions for each of the environmental variables that is uncertain. The method further includes defining an objective function such as a net present value of each fracture treatment over a 365 day period following the fracture treatment. The method includes determining an optimal value for each fracture control parameter according to the objective function by determining the fracture control parameter values that yield the best mean net present value given the variability in the environmental variables as described by their probability distributions.
Abstract:
A system for automatically optimizing a Field Development Plan (FDP) for an oil or gas field uses a fast analytic reservoir simulator to dynamically model oil or gas production from the entire reservoir over time in an accurate and rapid manner. An objective function defining a Figure of Merit (FoM) for candidate FDPs is maximized, using an optimization algorithm, to determine an optimized FDP in light of physical, engineering, operational, legal and engineering constraints. The objective function for the Figure of Merit, e.g., net present value (NPV) or total production for a given period of time, relies on a production forecast from the fast analytic reservoir simulator for the entire FDP. The position, orientation and dimensions of analytical model elements for the subsurface oil or gas field, as well as the physical properties associated with these elements, correlate to connected flow volume data from a Shared Earth Model (SEM). Uncertainty in the SEM is considered via stochastic sampling. In the presence of uncertainty, the optimum Field Development Plan (FoM) is selected by maximizing an objective function defining a risk-based Figure of Merit for the entire FDP.