Abstract
Rotodynamic multiphase pumps are usually equipped with many compression units to provide sufficient boosting pressure for the transportation of production fluid in gas oil field. It is a challenge to maintain pump performance while flow parameters in each stage vary due to the compressibility of gas-liquid phase. In this article, a stage-by-stage design method is proposed to improve the boosting capability of a multiphase pump. Variations of flow parameters in each stage are investigated based on computational fluid dynamics (CFD) numerical simulation. Available methods to determinate main impeller geometry parameters of impeller are discussed. The stage-by-stage design method is applied on a five-stage multiphase pump when the inlet gas volume fraction (GVF) are 30% and 50% separately. The second stage is modified base on its corresponding inlet flow parameters when inlet GVF is 30% while the second and third stage are modified when inlet GVF is 50%. Flow parameters, pressure distribution and velocity distribution are compared between the original pump and modified pump. Differential pressure of the modified pump increases by 53.72 kPa and 58.57 kPa respectively when inlet GVFs are 30% and 50%. The feasibility of the stage-by-stage design method is verified through the comparison results.
Highlights
In a subsea gas oil field, the production fluid is usually transported from the wellheads to the production facilities through long subsea pipelines and risers
In order to provide sufficient boosting pressure for the production fluid, a helico-axial multiphase pump is usually equipped with multi-stage which contains dozens or even hundreds of compression units when applied on the subsea gas oil fields.[4]
A stage-by-stage design method is proposed in this paper based on the variation characteristics of flow parameters in a five-stage multiphase pump
Summary
In a subsea gas oil field, the production fluid is usually transported from the wellheads to the production facilities through long subsea pipelines and risers. One of the challenges is to keep up a sufficient production rate and the right amount of pressure to flow fluid Due to this reason, multiphase pumps are widely used in subsea operations to overcome these issues. In order to provide sufficient boosting pressure for the production fluid, a helico-axial multiphase pump is usually equipped with multi-stage which contains dozens or even hundreds of compression units when applied on the subsea gas oil fields.[4] Flow conditions changes obviously in a multi-stage multiphase pump because of the existence and compressibility of gas. The gas-liquid two phase flow patterns inside flow passage of pump vary from isolated bubbles, bubbly flow, gas pocket flow and segregated gas flow as inlet gas volume fraction increases, which could significantly affect the pump performance and brings challenges to maintain the boosting capability of a pump.[5]
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