TY - THES

T1 - Management of Multiphase Flow in Pipelines: A Flow Assurance Study

AU - Ali, Ahmed Hussein Mahmoud Ali

N1 - embargoed until null

PY - 2020

Y1 - 2020

N2 - This thesis provides a Flow Assurance (FA) study of a gas condensate pipeline network that is planned to be constructed onshore in a continental climate with extremely cold winters and hot summers. The pipeline network is 33 km long in total and consists of five flowlines tied into a main trunk-line. A range of operating conditions is considered, where the analysis of the whole pipeline network is performed at target gas flowrate, as well as turndown, ramp-up, and shutdown conditions. OLGA [version 2018.1.0], a specialized dynamic multiphase flow simulator, is used to study the steady-state and transient behaviours of the system from a hydraulic standpoint and a thermal standpoint. Multiflash [version 7.0], a PVT and physical properties package, is used to create PVT tables and hydrate curves as input for OLGA. Line sizes, as reported in the Basis-of-Design, are confirmed, and more possible sizes, based on the given pressure rating, are examined. Pressure, temperature, velocity profiles are determined based on production profiles, along with flow regimes and liquid hold-ups. The predominant flow regimes in the network branches are determined under turndown flowrates, in addition to the minimum stable flowrate (MSFR) into the slug catcher, then the slugging characteristics in the pipeline and the liquid handling capabilities of the slug catcher are examined as flowrates are ramped up again. The required methanol injection flowrates are estimated, and the right insulations for flowlines are determined to prevent hydrate formation and/or wax deposition during production, and to allow for the required no-touch time set by the operator. Pigging simulations are performed to determine proper pigging velocities that avoid surging the slug catcher at the pipeline outlet, and pipeline packing is simulated to determine the time required to reach the pipeline design pressure during a process shutdown. The thesis also serves as a guide for carrying out FA studies: It elaborates on building the simulation model, setting up the simulation cases, and compares different methods of running the cases. Well models and IPRs are used to simulate the sources of the gas condensate instead of the typical mass sources, and all network branches are simulated simultaneously, rather than in isolation, to capture the dynamic effect of the different branches on one-another.

AB - This thesis provides a Flow Assurance (FA) study of a gas condensate pipeline network that is planned to be constructed onshore in a continental climate with extremely cold winters and hot summers. The pipeline network is 33 km long in total and consists of five flowlines tied into a main trunk-line. A range of operating conditions is considered, where the analysis of the whole pipeline network is performed at target gas flowrate, as well as turndown, ramp-up, and shutdown conditions. OLGA [version 2018.1.0], a specialized dynamic multiphase flow simulator, is used to study the steady-state and transient behaviours of the system from a hydraulic standpoint and a thermal standpoint. Multiflash [version 7.0], a PVT and physical properties package, is used to create PVT tables and hydrate curves as input for OLGA. Line sizes, as reported in the Basis-of-Design, are confirmed, and more possible sizes, based on the given pressure rating, are examined. Pressure, temperature, velocity profiles are determined based on production profiles, along with flow regimes and liquid hold-ups. The predominant flow regimes in the network branches are determined under turndown flowrates, in addition to the minimum stable flowrate (MSFR) into the slug catcher, then the slugging characteristics in the pipeline and the liquid handling capabilities of the slug catcher are examined as flowrates are ramped up again. The required methanol injection flowrates are estimated, and the right insulations for flowlines are determined to prevent hydrate formation and/or wax deposition during production, and to allow for the required no-touch time set by the operator. Pigging simulations are performed to determine proper pigging velocities that avoid surging the slug catcher at the pipeline outlet, and pipeline packing is simulated to determine the time required to reach the pipeline design pressure during a process shutdown. The thesis also serves as a guide for carrying out FA studies: It elaborates on building the simulation model, setting up the simulation cases, and compares different methods of running the cases. Well models and IPRs are used to simulate the sources of the gas condensate instead of the typical mass sources, and all network branches are simulated simultaneously, rather than in isolation, to capture the dynamic effect of the different branches on one-another.

KW - Multiphase flow

KW - Flow Assurance

KW - OLGA

KW - Mehrphasenströmung

KW - Flow Assurance

KW - OLGA

M3 - Master's Thesis

ER -