Improved sampling strategies for ensemble-based optimization

We are concerned with the efficiency of stochastic gradient estimation methods for large-scale nonlinear optimization in the presence of uncertainty. These methods aim to estimate an approximate gradient from a limited number of random input vector samples and corresponding objective function values. Ensemble methods usually employ Gaussian...

Informed production optimization in hydrocarbon reservoirs

The exploitation of subsurface hydrocarbon reservoirs is achieved through the control of production and injection wells (i.e., by prescribing time-varying pressures and flow rates) to create conditions that make the hydrocarbons trapped in the pores of the rock formation flow to the surface. The design of production strategies to exploit these...

Improving the ensemble-optimization method through covariance-matrix adaptation

Ensemble optimization (referred to throughout the remainder of the paper as EnOpt) is a rapidly emerging method for reservoirmodel-based production optimization. EnOpt uses an ensemble of controls to approximate the gradient of the objective function with respect to the controls. Current implementations of EnOpt use a Gaussian ensemble of...

CFD analysis and flow model reduction for surfactant production in helix reactor = CFD analiza i redukcija modela strujanja za proizvodnju surfaktanta u helix reaktoru

Flow pattern analysis in a spiral Helix reactor is conducted, for the application in commercial surfactant production. Step change response curves (SCR) were obtained from numerical tracer experiments by three-dimensional computational fluid dynamics (CFD) simulations. Non-reactive flow is simulated, though viscosity is treated as variable in...

Ensemble-based multi-objective optimization of on-off control devices under geological uncertainty

We consider robust ensemble-based (EnOpt) multi-objective production optimization of on-off inflow control devices (ICDs) for a sector model inspired on a real-field case. The use of on-off valves as optimization variables leads to a discrete control problem. We propose a re-parameterization of such discrete controls in terms of switching times,...

Value of multiple production measurements and water front tracking in closed-loop reservoir management

This paper extends previous work on value of information (VOI) assessment in closed-loop reservoir management (CLRM) to estimate the added value of performing multiple measurements along the producing life of the reservoir. The new procedure is based on the workflow from our previous paper which allows to quantify the VOI of a single observation...

Ensemble-based hierarchical multi-objective production optimization of smart wells

In an earlier study, two hierarchical multiobjective methods were suggested to include short-term targets in life-cycle production optimization. However, this earlier study has two limitations: (1) the adjoint formulation is used to obtain gradient information, requiring simulator source code access and an extensive implementation effort, and (2...

Robust ensemble-based multi-objective optimization

We consider robust ensemble-based multi-objective optimization using a hierarchical switching algorithm for combined long-term and short term water flooding optimization. We apply a modified formulation of the ensemble gradient which results in improved performance compared to earlier formulations. We also apply multi-dimensional scaling to...

CFD analysis and flow model reduction for surfactant production in helix reactor

Flow pattern analysis in a spiral Helix reactor is conducted, for the application in the commercial surfactant production. Step change response curves (SCR) were obtained from numerical tracer experiments by three-dimensional computational fluid dynamics (CFD) simulations. Non-reactive flow is simulated, though viscosity is treated as variable...

Integrated design of the feedback controller and topography estimator for atomic force microscopy

In atomic force microscopy(AFM) the force between the measurement tip and the sample is controlled in a feedback loop to prevent damage of the tip and sample during imaging, and to convert the measurement of the tip–sample force into an estimate of the sample topography. Dynamical uncertainties of the system limit the achievable control...

Improving the ensemble optimization method through covariance matrix adaptation (CMA-EnOpt)

Ensemble Optimization (EnOpt) is a rapidly emerging method for reservoir model based production optimization. EnOpt uses an ensemble of controls to approximate the gradient of the objective function with respect to the controls. Current implementations of EnOpt use a Gaussian ensemble with a constant standard deviation, i.e. a diagonal...

Fast model based approximation of the closed-loop performance limits of gas/liquid inline separators for accelerated design

A current trend in the oil and gas industry is to use compact so called inline separators (ILS). Unlike their large conventional counterparts, the operation of these separators is very sensitive towards variations in the multiphase flow to be separated. This sensitivity easily results in operational problems and economic loss and may prohibit...

Improved economic operation of MSWC plants with a new model based PID control strategy

Municipal solid waste combustion (MSWC) plant operators are currently under an increasing pressure to optimize the economic performance of their plants. A route with high potential for optimizing this performance is by improving the performance of the MSWC plant combustion control system, which typically is of the PID-type. In this paper,...

Nonlinear model predictive control with moving horizon state and disturbance estimation - With application to MSW combustion

This paper presents a nonlinear model predictive control (NMPC) strategy that can be used to tackle model predictive control problems that involve relatively simple nonlinear dynamic models, as for example obtained with first-principles modeling. The main feature of the proposed NMPC strategy is the usage of a moving horizon estimator (MHE) for...

Closed-loop identification of multivariable processes with part of the inputs controlled

In many multivariable industrial processes a subset of the available input signals is being controlled. In this paper it is analyzed in which sense the resulting partial closed-loop 1 identification problem is actually a full closed-loop problem, or whether one can benefit from the presence of noncontrolled inputs to simplify the identification...

MIMO closed-loop identification of an MSW incinerator

In this paper, the application of a specific system identification procedure to a municipal solid waste (MSW) incinerator is discussed. This procedure is a combination of, on the one hand, a particular closed-loop identification method called the two-stage method and, on the other hand, the approach of high-order multiple input multiple output ...