Method and a system for enhanced flow line control

Patent metadata

Field	Value
Publication number	US-9323252-B2
Application number	US-92026706-A
Country	US
Kind code	B2
Filing date	May 9, 2006
Priority date	May 10, 2005
Publication date	Apr 26, 2016
Grant date	Apr 26, 2016

Abstract

A method for automatically controlling a flow in a flow line system including a flow line, a flow line inlet and outlet, and a control valve located in the flow line at the outlet. The method includes controlling the opening of the valve with a control unit. An outlet flow rate is measured or estimated from the flow line. The valve is opened. It is determined if a sudden drop occurs in any of the measurements or estimates. It is decided if a liquid blockage in the flow line is present or approaching. If a liquid blockage is indicated as present or approaching, the opening of the valve is increased by an amount determined by the measurements or estimates. Any further manipulation of the valve is inhibited before a non-zero time period has expired. The steps are repeated. Also a system and a computer program product.

First claim

The invention claimed is:

1. A method for automatically controlling a multiphase flow in a flow line system, said flow line system comprising a flow line, a flow line inlet and flow line outlet, and a control valve or choke located in the flow line at the flow line outlet, the method comprising:
controlling opening of the control valve or choke in a nonlinear manner with a control unit,
measuring or estimating the opening of the control valve or choke and at least one parameter at the flow line outlet selected from the group consisting of an outlet flow rate, a pressure upstream of the control valve or choke, a pressure difference across the control valve or choke, a fluid density upstream of the control valve or choke, a fluid temperature upstream of the control valve or choke, and any combination thereof, the opening of the control valve or choke being directly measured or estimated to be used in controlling the control valve or choke to minimize disturbances in the multiphase flow,
determining if a sudden drop occurs in one or more of said measurements or estimates only,
measuring or estimating a trend value of the outlet flow rate or the pressure upstream of the control valve or choke, or the pressure difference across the control valve or choke, or the fluid density, or the fluid temperature, or any combination thereof, and the opening of the control valve or choke in a first window moving with time,
measuring or estimating a trend value of the outlet flow rate or the pressure upstream of the control valve or choke, or the pressure difference across the control valve or choke, or the fluid density, or the fluid temperature, or any combination thereof, and the opening of the control valve or choke in a second window moving with time, and if said trend value measured or estimated in the first window falls below a defined percentage of the trend value measured or estimated in the second window
deciding if a liquid blockage in the flow line is present or approaching based on said measurements or estimates,
and if a liquid blockage is indicated as present or approaching, adjusting intermittently, via the control unit, the control valve or choke by
increasing the opening of the control valve or choke abruptly by an amount determined by said measurements or estimates,
inhibiting, via the control unit, any further manipulation of the control valve or choke before a non-zero time period has expired, and thereby waiting the non-zero time period during which the control unit is controlling flow in the flow line system before manipulating the opening of the control valve or choke again, and

repeating the steps according to the above.

2. The method according to claim 1 , further comprising:
measuring or estimating a flow rate or a pressure, or a fluid temperature at the inlet of the flow line,
determining a mass balance of the flow line system, and
deciding if said liquid blockage is present or approaching based on said mass balance.

3. The method according to claim 1 , further comprising:
measuring a pressure differential across the control valve or choke, and if said pressure differential exceeds a predetermined or automatically computed value,
inhibiting manipulation of the control valve or choke.

4. The method according to claim 1 , further comprising:
measuring said outlet flow rate with a multiphase flow meter.

5. The method according to claim 1 , further comprising:
estimating said outlet flow rate from measurements of a pressure differential across the control valve or choke.

6. The method according to claim 1 , further comprising:
estimating said outlet flow rate from measurements of a pressure differential across the control valve or choke and measurements of valve or choke opening and/or density of the fluid flowing in the flow line.

7. The method according to claim 1 , further comprising:
controlling the control valve or choke only when a predefined time period has expired since last opening step.

8. A system for automatically controlling a multiphase flow in a flow line system, said flow line system comprising a flow line inlet and flow line outlet, and a control valve or choke located in the flow line at the flow line outlet, the system comprising:
a control unit controlling opening of the control valve or choke in a nonlinear manner,
means for measuring or estimating the opening of the control valve or choke and at least one parameter at the flow line outlet selected from the group consisting of an outlet flow rate a pressure upstream of the control valve or choke, a pressure difference across the control valve or choke, a fluid density upstream of the control valve or choke, a fluid temperature upstream of the control valve or choke, and any combination thereof, the opening of the control valve or choke being directly measured or estimated to be used in controlling the control valve or choke to minimize disturbances in the multiphase flow,
means for determining if a sudden drop occurs in one or more of said measurements or estimates only,
measuring or estimating a trend value of the outlet flow rate or the pressure upstream of the control valve or choke, or the pressure difference across the control valve or choke, or the fluid density, or the fluid temperature, or any combination thereof, and the opening of the control valve or choke in a first window moving with time,
measuring or estimating a trend value of the outlet flow rate or the pressure upstream of the control valve or choke, or the pressure difference across the control valve or choke, or the fluid density, or the fluid temperature, or any combination thereof, and the opening of the control valve or choke in a second window moving with time, and if said trend value measured or estimated in the first window falls below a defined percentage of the trend value measured or estimated in the second window
means for deciding if a liquid blockage in the flow line is present or approaching based on said measurements or estimates,
and if a liquid blockage is indicated as present or approaching, the control unit adjusting intermittently the control valve or choke by,
means for abruptly increasing the opening of the control valve or choke by an amount determined by said measurements or estimates, and
means for inhibiting, via the control unit, any further manipulation of the control valve or choke before a non-zero time period has expired, and thereby waiting the non-zero time period during which the control unit is controlling flow in the flow line system before manipulating the opening of the control valve or choke again.

9. The system according to claim 8 , further comprising:
means to enable the control unit to control the control valve or choke only when a predefined time period has expired since last opening step.

Assignees

• Slupphaug Olav
• Kristiansen Dag
• Bjune Bjørn
• Kristiansen Veslemøy
• Abb Research Ltd

Inventors

• Slupphaug Olav
• Kristiansen Dag
• Bjune Bjørn
• Kristiansen Veslemøy

Classifications

• Y10T137/0379

  By fluid pressure · CPC title

• G05D7/0635 Primary

  by action on throttling means (G05D7/0688, G05D7/0694 take precedence) · CPC title

• E21B43/12 Primary

  Methods or apparatus for controlling the flow of the obtained fluid to or in wells (E21B43/25 takes precedence; valve arrangements E21B34/00) · CPC title

• Y10T137/7759

  Responsive to change in rate of fluid flow · CPC title

• E21B2200/09

  Detecting, eliminating, preventing liquid slugs in production pipes · CPC title