Control of a steam-assisted gravity drainage (SAGD) process is a challenging task, because of the presence of various uncertainties, such as geological uncertainty and steam quality uncertainty. They often lead to constraint violations and performance degradation. In this work, a chance-constrained model predictive control (CCMPC) method is presented to generate a safe and optimal control strategy, considering the presence of uncertainties. A novel robust optimization method is applied to solve the chanceconstrained optimization problem under general distribution of uncertainties. Two case studies are presented to demonstrate the proposed approach. Furthermore, the modeling of SAGD process is discussed, and the proposed robust optimization-based CCMPC is tested using a reservoir simulator (Petroleum Experts) of the SAGD process. The proposed approach reduces constraint violations that are due to uncertainties and achieves satisfactory performance.
Process measurements play a significant role in process identification, control, and optimization. However, they are often corrupted by two types of errors, random and gross errors. The presence of gross errors in the measurements affects the reliability of optimization and control solutions. Therefore, in this work, we characterize the measurement noise model using a Gaussian mixture distribution, where each mixture component denotes the error distribution corresponding to random error and gross error, respectively. On the basis of this assumption, we propose a maximum likelihood framework for simultaneous steadystate data reconciliation and gross error detection. Since the proposed framework involves the noise mode as a hidden variable denoting the existence of gross errors in the data, it can be solved using the expectation maximization (EM) algorithm. This approach does not require the parameters of the error distribution model to be preset, rather they are determined as part of the solution. Several case studies are presented to demonstrate the effectiveness of the proposed approach.
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