Estudo experimental de bombas de BCS operando com escoamento bifásico gás-líquido / Experimental investigation of two-phase gas-liquid flow performance of electrical submersible pump

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

21/12/2011

RESUMO

The use of electrical submersible pumps (ESP) under gas-liquid flow is very common in the oil industry. At constant liquid flow rate a dramatic degradation on pump head is observed as gas flow rate increases. Natural instabilities of two-phase flow may cause the centrifugal pump to surge at rather low gas void fraction (GVF), as evidenced by a critical point in the pressure gain x flow rate curve, a phenomenon referenced as surging point . Further increase in GVF may cause the gas to fill most of the pump impeller, making the liquid flow rate to decrease down to zero, a phenomenon known as gas locking . Therefore, knowledge of the conditions for which the pump starts to surge is of utmost importance and can only be understood through experimental investigation. The goal of this work is to present the experimental ESP performance curves (head, brake horsepower and efficiency) when operating with gas-liquid mixtures. For that purpose the characteristic curves were determined for one prototype of ESP, operating with water and two-phase air-water mixtures with GVF ranging from 0 to 10 % at different rotational speed, intake pressure and liquid flow rate. The ESP prototype is designed to make possible the flow visualization inside the pump. The performance of a gas handler was also tested in order to determine their operational characteristics. Tests were carried out on an ESP testing bench, where flow parameters (air and water flow rates, pressure and temperature at the inlet and outlet of the pump) and mechanical parameters (shaft torque and speed) were measured. A significant decrease in pump head, and consequently in pump efficiency, was observed as the air fraction was increased. Phenomena like surging and gas locking were observed during these tests. The rotational speed and intake pressure affect the critical GVF at the surging conditions. Increasing the rotational speed and intake pressure moves de critical GVF to higher values extending the operational range the ESP.

ASSUNTO(S)

bombas centrífugas engenharia de petróleo escoamento bifásico gás escoamento instável (dinâmica dos fluídos) centrifugal pumps petroleum engineering two-phase flow unstable flow (fluid dynamics) gas

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