Screw pump calculation

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Department of «Petroleum Engineering»

PET 4383 - Offshore Fields Development

Practical work №11

Topic:  Screw pump calculation

Problem №1

Select a screw pump of OKB BN design for oil production from the well. The pump is driven by submersible electric motor PED-10-103 with power 10kW and n=3000 rpm and is lowered into the well on 62 mm tubing. Well flow rate Q=40 tons/day, design pressure P=6 MPa.

Relative density of produced liquid ρж=0,9. Static liquid level in the well hst=500 m; excess of liquid level in the trap over the wellhead h2=3 m; pressure in the trap hc=11 m of liquid; well productivity coefficient K=50m3/day-MPa. Depression at steady flow rate and at linear filtration of liquid is determined by the formula 1

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where ρw is the density of water, 1000kg/m3.

According to formula (1) we obtain

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The required head (in m. waterst) for obtaining the given flow rate is defined as the sum of formula 2

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The value of һtr is close to zero, Ршт is the pressure drop in the connector.

Consequently, according to formula (2) we have

Нскв=81,6+(500+3+11)0,9+Ршт =543,6+ Ршт.

According to the nature of the pump flow rate Q=40 m3/day corresponds to a head H=600 m of water column.

Taking the scheme of installation without bypassing the liquid, but the installation of additional resistance (fitting), we have a pressure drop in the fitting

Ршт+ =600-543,6=54,4 m water. st.

With change of working characteristic of screw pump Q - H it is necessary to change the value, keeping constant flow rate Q=40 m3 /day.

Options for independent solution

Theoretical questions:

1. Gravity methods?
2. Magnetic methods?
3. Seismic methods?