• A two-layer structure for stabilization and optimization of an oil gathering network 

      Codas, Andres; Jahanshahi, Esmaeil; Foss, Bjarne Anton (Journal article; Peer reviewed, 2016)
      In this work, we present the control and optimization of a network consisting of two gas-lifted oil wells, a common pipeline-riser system and a separator. The gas-lifted oil wells may be open-loop unstable. The regulatory ...
    • Anti-Slug Control Experiments Using Nonlinear Observers 

      Jahanshahi, Esmaeil; Skogestad, Sigurd; Grøtli, Esten Ingar (Journal article; Peer reviewed, 2013)
      Abstract: To prevent slug-flow on offshore oil production units, controlling a subsea pressure is the recommended solution. However, the subsea pressure is not often available as a measurement. The top-side pressure is ...
    • Anti-Slug Control with Non-Linear State Estimation 

      Syre, Terese Vardenær (Master thesis, 2012)
      In offshore production, the two-phase mixture of oil and gas is transported from the seabed oil wells to the surface facilities by pipelines and risers. The two-phase flow can have different flow regimes, where severe ...
    • Control of Steady-state Gradient of an Ammonia Reactor using Transient Measurements 

      Bonnowitz, Harro; Straus, Julian; Krishnamoorthy, Dinesh; Jahanshahi, Esmaeil; Skogestad, Sigurd (Journal article; Peer reviewed, 2018)
      This paper presents the application of a steady-state real-time optimization strategy using transient measurements to an ammonia synthesis reactor case. We apply a new method for estimating the steady-state gradient of the ...
    • Control Solutions for Multiphase Flow: Linear and nonlinear approaches to anti-slug control 

      Jahanshahi, Esmaeil (Doktoravhandlinger ved NTNU, 1503-8181; 2013:271, Doctoral thesis, 2013)
      Severe-slugging flow in offshore production flowlines and risers is undesirable and effective solutions are needed to prevent it. Automatic control using the top-side choke valve is a recommended anti-slug solution, but ...
    • Feedback Real-Time Optimization Strategy Using a Novel Steady-state Gradient Estimate and Transient Measurements 

      Krishnamoorthy, Dinesh; Jahanshahi, Esmaeil; Skogestad, Sigurd (Journal article; Peer reviewed, 2019)
      This paper presents a new feedback real-time optimization (RTO) strategy for steady-state optimization that directly uses transient measurements. The proposed RTO scheme is based on controlling the estimated steady-state ...
    • Gas-lift Optimization by Controlling Marginal Gas-Oil Ratio using Transient Measurements 

      Krishnamoorthy, Dinesh; Jahanshahi, Esmaeil; Skogestad, Sigurd (Journal article; Peer reviewed, 2018)
      This paper presents the application of a steady-state gradient control using transient measurements to a gas-lift optimization problem. Optimal operation of a gas-lifted field involves controlling the marginal gas-oil ratio ...
    • L1 Adaptive Anti-Slug Control 

      Ohrem, Sveinung Johan; Holden, Christian; Jahanshahi, Esmaeil; Skogestad, Sigurd (Journal article; Peer reviewed, 2017)
      In many multiphase pipeline-riser systems, anti-slug control is necessary to ensure steady and optimal operation. In this paper, we propose using an ℒ1 adaptive controller as an augmentation to standard PI control to ...
    • Nonlinear model-based control of two-phase flow in risers by feedback linearization 

      Jahanshahi, Esmaeil; Skogestad, Sigurd; Grøtli, Esten Ingar (Journal article, 2013)
      Active control of the production choke valve is the recommended solution to prevent severe slugging flow conditions at offshore oilfields. The slugging flow constitutes an unstable and highly nonlinear system; the gain of ...
    • Online PID Tuning for Unstable Processes: Application to Anti-Slug Control 

      Nilsen, Anne Sofie (Master thesis, 2013)
      Slug flow is an undesired multiphase flow phenomena causing problems in the processing of oil and gas. Anti-slug control is therefore an important research topic. Satisfactory results have been achieved in anti-slug control ...
    • Plantwide control of an oil production network 

      Jahanshahi, Esmaeil; Krishnamoorthy, Dinesh; Codas Duarte, Andres; Foss, Bjarne Anton; Skogestad, Sigurd (Peer reviewed; Journal article, 2020)
      In this paper, we consider Real-Time Optimization (RTO) and control of an oil production system. We follow a systematic plantwide control procedure. The process consists of two gas-lift oil wells connected to a pipeline-riser ...
    • Robust control solutions for stabilizing flow from the reservoir: S-Riser experiments 

      Esmaeilpour Abardeh, Mahnaz (Master thesis, 2013)
      One of the best suggested solutions for prevention of severe-slugging flow conditions at offshore oilfields is the active control of the production choke valve. This thesis is a study of robust control solutions for ...
    • Stabilizing Slug Control Using Subsea Choke Valve 

      Lieungh, Mats (Master thesis, 2012)
      This thesis study the possibility of riser slugging control in oshore oil productionusing a subsea choke valve. A 5-state simplied model of a well-pipelinerisersystem is introduced and tted to a reference model in the ow ...