Here generalized analysis is given for transport of highly paraffin and highly congealing oil taking into account layout, technology of transport and construction features of subsea oil pipeline.

In accordance with results of physical experiments for active oil pipelines the generalized mathematical model was made to explain thermohydrodynamic regime of telescopic construction oil pipe operation for paraffin and highly congealing oil transport.

Thermohydrodynamic and mass exchange process in subsea pipelines are explained by differential equation system: flow (1), continuity (2), energy (3), heavy hydrocarbon fraction concentration forming wall depositions (4), adsorbtion kinetic and hydrodynamic desorbtion of wall oil depositions (5).

Based on mathematical model of existing subsea oil pipeline, new computer method was created for analysis of thermohydrodynamic and technological process while transporting highly paraffin and highly congealing oils. There was developed respective software package allowing to study both steadied and unsteady transport process in wide range of thermobaryc and technological parameters change characterizing oil pipeline operation.

Proposed method of analysis is intended for designing of new pipelines and modification of old subsea oil pipelines and change of transport technology in active pipelined, i.e. optimization of transport parameters and determination of oil pipeline safe operation limit eliminating critical transport regime-telescopic pipeline "freezing".

Digital experiments have shown that in certain technological transport condition the critical operation regime starts proceeding from intensive heavy hydrocarbon depositions (in solid phase) at inside pipeline surface. It is accompanied by spontaneous (uncontrollable) decrease (due to hydraulic resistance) of pipeline throughput. This process (if timely special measures are not taken) will result in full transport stoppage and subsequent pipeline "freezing".

Based on analysis of different technological parameters influence on thermohydrodynamic pipeline operation regime, there were considered and proposed method of thermal, hydrodynamic and chemical influence on wall depositions which allow to eliminate critical pipeline operation regime at different flow rates.

Here the results are given for digital simulation of pipeline operation in form of diagrams.

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