By-pass pigs for two-phase flow pipelines

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:418207

Wu, H L; Spronsen, G van; Klaus, E H; Stewart, D M

Pigging two-phase pipelines normally leads to the generation of large liquid slug volumes in front of the pig requiring excessively large separators or slug catchers. The concept of using a high by-pass pig to disperse the liquid and reduce the maximum liquid production rate prior to pig arrival is under investigation by Shell Exploration and Production companies. A simulation model of the dynamics of the pig and related two-phase flow behavior in the pipeline was used to predict the performance of by-pass pigs. Field trials in a dry gas pipeline were carried out to provide friction data and to validate the model. It was then used to explore operating possibilities in a two-phase lie which led to the follow-up trial in a 15.6 km, 20 inch OD two-phase offshore interfield pipeline with risers. Whereas the volume of liquid swept in front of the pig would be 179 m{sup 3} if the by-pass fraction were zero, a reduction of 70% to 53m{sup 3} was achieved in the field with a by-pass fraction of 10%. The predicted mobility of the high by-pass pig in the pipeline and risers was verified and the beneficial effects due to the by-pass concept exceeded the prediction of the simplified model. The significant gains of using a by-pass pig in modifying gas and liquid production rates during pigging operation have been demonstrated. The method can widen the possibility of applying two-phase flow pipeline transportation to cases where separator or slug catcher capacity are limited for reasons of practicality or cost.

• OSTI ID: 418207
• Report Number(s): CONF-960348--
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
DESIGN
FLOW MODELS
MAINTENANCE FACILITIES
NATURAL GAS
NATURAL GAS DISTRIBUTION SYSTEMS
NATURAL GAS LIQUIDS
PERFORMANCE
PIPELINES
REMOVAL
TRANSPORT
TWO-PHASE FLOW