Real-Time Optimization under Uncertainty Applied to a Gas Lifted Well Network

Bjarne Foss,Sigurd Skogestad,Dinesh Krishnamoorthy

doi:10.3390/pr4040052

Bjarne Foss, Sigurd Skogestad

Open Access

https://doi.org/10.3390/pr4040052

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Journal: Processes	Publication Date: Dec 15, 2016
Citations: 46	License type: CC BY 4.0

Affiliation: Norwegian University of Science and Technology

Abstract

In this work, we consider the problem of daily production optimization in the upstream oil and gas domain. The objective is to find the optimal decision variables that utilize the production systems efficiently and maximize the revenue. Typically, mathematical models are used to find the optimal operation in such processes. However, such prediction models are subject to uncertainty that has been often overlooked, and the optimal solution based on nominal models can thus render the solution useless and may lead to infeasibility when implemented. To ensure robust feasibility, worst case optimization may be employed; however, the solution may be rather conservative. Alternatively, we propose the use of scenario-based optimization to reduce the conservativeness. The results of the nominal, worst case and scenario-based optimization are compared and discussed.

Highlights

The offshore production of oil and gas is a complex process where a lot of decisions have to be taken to meet the goals in the short, medium and long run, ranging from planning and asset management to small corrective actions
The long-term decisions involve selecting an investment strategy, operation model, infrastructure etc, which is typically known as asset management
Since well 2 has lower expected GOR, one would prioritize well 2 over well 1. This is seen in the true optimal gas lift rates in Table 3, where well 1 is prioritized over well 2 for the nominal case and vice versa for the worst case realization

Summary

Introduction

The offshore production of oil and gas is a complex process where a lot of decisions have to be taken to meet the goals in the short, medium and long run, ranging from planning and asset management to small corrective actions. There are decisions taken on a horizon of one to five years such as selecting drilling schedules and production and injection strategies, known as reservoir management. This is followed by decisions that have to be taken on a decision horizon, ranging from a few hours to days known as Daily Production

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