Automatic Start-up and Control of Artificially Lifted Wells
Artificial lift in oil wells using a downhole pump has received much attention
the last decades and is established as a reliable and efficient lifting
method. In particular, artificial lift using an electric submersible pump
(EPS) has proven to be an important alternative in deep wells with high
production rate requirements.
This thesis investigate the problem of controlling the ESP intake pressure
under rigid ESP operational constraints and input requirements, using the
ESP frequency and choke position as control inputs.
A mathematical model of a system containing ESP lifted wells is created
and a control strategy that fulfil the control requirements is proposed.
The model is an extension of the ESP model developed by Amundsen(2010) and
contain four ESP lifted wells. Mathematical proof of open-loop stability
is derived based on analysis of a linearized well model. Also, closed-loop
stability for the linearized model is proved based on frequency analysis.
The proposed control strategy is tested on the model in a range of different
case study. The control system display a capability of minimizing the
control error while keeping the ESP operated within the given constraints,
with an optimal combination of control inputs. Simulation results indicate
that the proposed control strategy is capable of handling a step-change
in ESP intake pressure, ESP tripping, and ESP and booster-pump start-up/
Place, publisher, year, edition, pages
Institutt for teknisk kybernetikk , 2011. , 120 p.
IdentifiersURN: urn:nbn:no:ntnu:diva-23579Local ID: ntnudaim:5947OAI: oai:DiVA.org:ntnu-23579DiVA: diva2:668124
Aamo, Ole Morten, ProfessorPavlov, Alexey