Schlumberger Technology Corporation

David J Wilkinson

Benoit Couet

Terizhandur S Ramakrishnan

William John Bailey

Rogerio Tadeu Ramos

Kashif Rashid

Ian D Bryant

Nikita Chugunov

Joseph Ayoub

William E Kenyon

William F Murphy

Hugues A Djikpesse

Andrew J Reischer

Robert Burridge

Edmund J Fordham

T S Ramakrishnan

Lawrence M Schwartz

Vincent Dury

Bernard Elie Theron

Saumil Ambani

Eren Cetinkaya

Wenyu Kong

Methods are disclosed for assigning a value to a geological asset or information relating thereto in the presence of private and public sources of uncertainties. The private and public uncertainties associated with a geological asset or information associated therewith are defined, and private uncertainties are assigned a subjective probability representing the best state of knowledge currently available. A multi-dimensional valuation-time lattice is constructed using the subjective probabilities for the private uncertainties and using risk-neutral probabilities for the public uncertainties. A backward recursion through the multi-dimensional lattice is performed in order to generate a present value for the asset given the present information available. During the backward recursion, a tally of delta hedging coefficients is generated and stored in order to provide an operational 'map' or 'decision pathway' should the project move forward.

Method of valuation of geological asset or information relating thereto in the presence of uncertainties

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.

Proxy methods for expensive function optimization with expensive nonlinear constraints

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.

System, method, and apparatus for fracture design optimization

Methods for optimization of oil well production with deference to reservoir and financial uncertainty include the application of portfolio management theory to associate levels of risk with Net Present Values (NPV) of the amount of oil expected to be extracted from the reservoir. Using the methods of the invention, production parameters such as pumping rates can be chosen to maximize NPV without exceeding a given level of risk, or, for a given level of risk, the minimum guaranteed NPV can be predicted to a 90% probability. An iterative process of generating efficient frontiers for objective functions such as NPV is provided.

Optimization of oil well production with deference to reservoir and financial uncertainty

A method and apparatus for the separation of the water from the oil/gas in the well itself, down-hole, in which gravity is allowed to work on the mixture in a non-vertical section of the well, and then, using separated flow paths, the gravity-separated components pumped to the surface or into a subterranean discharge zone. Detectors are used to control the pumping so as to keep the unsettled/unseparated mixture away from the flow paths. Preferably the discharge zone is chosen to have a formation pressure which is lower than the pressure of the producing zone.

Separation of oil-well fluid mixtures

In this invention a new interpretation methodology has been developed. A pore structure model is used to compute the relaxation behavior. This model is then used as the kernel of a best-fit inversion scheme against the measured data, in contrast to inverting for a T.sub.2 distribution that relies on regularization. Parameters of the model are obtained by 'best fitting' the model with the data. The method considers a geometrical or physical model comprising both intergranular and intragranular porosity (microporosity). The NMR relaxation is computed by one of the several methods. The model is compactly represented by a set of physical parameters that are iterated upon until a match with relaxation data is obtained in the best fit sense. The result is obtained in terms of these physical parameters, and then integrated with other types of measurements.

Method for estimating pore structure in carbonates from NMR measurements

A logging tool provides a log of fractional flow characteristics of formations surrounding an earth borehole. The logging tool is suspended in the borehole and resistivity measurements are made at different radial depths of investigation while the logging tool is moved through the borehole to obtain several resistivity logs. Model fractional flow parameters are selected, and a formation conductivity model as a function of the model fractional flow parameters is determined. Several simulated resistivity log values are generated at respective radial depths of investigation from the formation conductivity model. The simulated resistivity log values are compared with values from the resistivity logs of the resistivity measurements to obtain an error indication. The model fractional flow parameters is modified accordingly. Steps are repeated until a predetermined criterion is met, then an output of formation fractional flow characteristics is produced.

Well logging method for determining fractional flow characteristics of

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Ridgefield, CT, United States of America

David J Wilkinson