Includes bibliographical references.
|Statement||author, Saeid Mokhatab.|
|LC Classifications||TN871.3 .M65 2010|
|The Physical Object|
|LC Control Number||2009054184|
Intends to predict severe slugging behavior in a catenary riser, this title presents a review of the literature on severe slugging. It describes a developed model of the offshore production rig, which is used as a basis to study dynamic interactions between the riser and downstream receiving facilities in the offshore production systems. A review of the existing literature on severe slugging is presented in this manuscript. It also describes a new developed model of the offshore production rig, which is used as a basis to study. Abstract: Active control of the production choke valve is the recommended solution to prevent severe slugging ow conditions at o shore oil elds. The focus of this work is to nd the structure of a simple, yet robust anti-slug control system. In order to nd suitable control variables for stabilization, a controllability analysis of the system. Severe slugging • Terrain dominated phenomenon, characterized by the formation and cyclical production of long liquid slugs and fast gas blowdown. • Instability that may may appear for low gas and liquid flow rates. • Main issues related to severe slugging are: High average back pressure at well head, causing tremendous production losses.
Slugging has been recognized as a serious problem in offshore oil fields because the irregular flow caused by slugging can cause serious operational problems for downstream surface facilities (e.g., overflow of inlet separators). In an offshore oil and gas production facility, pipeline-riser systems are required to transport two-phase hydrocarbons from subsurface oil and gas wells to a central production platform. Severe slugging reaching several thousands pipe diameters may occur when transporting gas and liquid in these pipeline-riser systems. Severe Slugging Stage 1 Terrain Induced Slug - Severe Gas blockage can occur in downward sloped flow line at riser base A liquid slug begins to form in the riser Gas Liquid. 9 In Offshore Risers: • Add riser base gas injection • Increase backpressure. 17 Turn Up Slugs. Slugging frequently encountered in gas-liquid two-phase flow is one of the challenging flow-assurance problems for such long pipeline-riser systems. Particularly, severe slugging occurs at low gas.
Severe slugging is considered to be an unstable flow regime in the sense that it is associated with large and abrupt fluctuations in the pipe pressure and in the gas and liquid flow rates at the outlet. The process of severe slugging formation can be described as taking place according to . Severe ‘slugging’ is an operational problem associated with offshore oil and gas production systems, particularly for ageing oil fields. The conventional approach, active slug control, is effective. However, it requires subsea instrumentation which is costly to install and maintain, and it may reduce oil production. Severe slug flow (i.e., terrain-dominated slug flow) was studied in a simulated offshore pipeline riser-pipe system. Severe slug flow is characterized by extremely long liquid slugs generated at the base of the vertical riser. This phenomenon occurs at low gas . Severe Slugging of type 2. The transitional severe slugging of type 2 is qualitatively similar to SS1, but the slug length is shorter than the height of the riser and it often has intermittent unstable oscillations. In Fig. 3 four stages of SS2 are illustrated. Fig. 3: Stages for severe slugging of type 2 (a) a graphical illustration (b) marked.