Measuring flow rates of multiphase fluids

Patent metadata

Field	Value
Publication number	US-12326353-B2
Application number	US-202217813540-A
Country	US
Kind code	B2
Filing date	Jul 19, 2022
Priority date	Jul 19, 2022
Publication date	Jun 10, 2025
Grant date	Jun 10, 2025

Abstract

A multiphase fluid is flowed from a flow pipe to a U-bend. Several differential pressures of the multiphase fluid flowing through the flow pipe and U-bend are measured. A total flow rate of the multiphase fluid is determined at least based on the measured differential pressures. In some cases, flow rates of each of the phases of the multiphase fluid can be determined at least based on the measured differential pressures.

First claim

What is claimed is:

1. A system comprising:
a U-bend configured to flow a multiphase fluid, the U-bend comprising:
a first conduit;
a second conduit, wherein a cross-sectional flow area of the first conduit is substantially the same as a cross-sectional flow area of the second conduit; and
a connecting conduit connecting the first conduit to the second conduit;

a third conduit configured to flow the multiphase fluid, the third conduit having a cross-sectional flow area that is different from the cross-sectional flow area of the first conduit;
a first bend connecting the third conduit to the first conduit;
a fourth conduit configured to flow the multiphase fluid, the fourth conduit parallel to and in-line with the third conduit, the fourth conduit having a cross-sectional flow area that is substantially the same as the cross-sectional flow area of the third conduit;
a second bend connecting the fourth conduit to the second conduit;
a first differential pressure sensor coupled to the third conduit and to the first conduit, wherein the first differential pressure sensor is configured to measure a first differential pressure of the multiphase fluid across the first bend;
a second differential pressure sensor coupled to the second conduit and to the fourth conduit, wherein the second differential pressure sensor is configured to measure a second differential pressure of the multiphase fluid across the second bend; and
a computer, comprising:
a processor communicatively coupled to the first differential pressure sensor and to the second differential pressure sensor; and
a computer-readable storage medium coupled to the processor and storing programming instructions for execution by the processor, the programming instructions instructing the processor to perform operations comprising:
receiving a first differential pressure signal from the first differential pressure sensor, the first differential pressure signal representing the first differential pressure of the multiphase fluid;
receiving a second differential pressure signal from the second differential pressure sensor, the second differential pressure signal representing the second differential pressure of the multiphase fluid;
receiving, as input, a mixture density of the multiphase fluid; and
determining a total flow rate of the multiphase fluid at least based on the first differential pressure, the second differential pressure, and the mixture density of the multiphase fluid.

2. The system of claim 1 , wherein the first differential pressure sensor is coupled to the third conduit at a first location and to the first conduit at a second location, and the first location and the second location are separated by a specified height with respect to gravity.

3. The system of claim 2 , wherein the second differential pressure sensor is coupled to the second conduit at a third location and to the fourth conduit at a fourth location, and the third location and the second location are separated by the specified height with respect to gravity.

4. The system of claim 3 , wherein the total flow rate of the multiphase fluid is determined as a first total mass flow rate of the multiphase fluid at least based on a first differential pressure equation:
m T1 =C d1 ×ε 1 ×K 1 ×√{square root over (2×ρ×(Δ P 1 −ρ×g×h ))},

wherein m T1 is the first total mass flow rate of the multiphase fluid, C d1 is a first discharge coefficient, ε 1 is a first expansion factor, K 1 is a first fixed geometry factor proportional to the cross-sectional flow area of the first conduit, ΔP 1 is the first differential pressure, ρ is the mixture density of the multiphase fluid, g is an acceleration due to gravity, and h is the specified height.

5. The system of claim 4 , wherein the total flow rate of the multiphase fluid is determined as a second total mass flow rate of the multiphase fluid at least based on a second differential pressure equation:
m T2 =C d2 ×ε 2 ×K 2 ×√{square root over (2×ρ×(Δ P 2 +ρ×g×h ))},

wherein m T2 is the second total mass flow rate of the multiphase fluid, C d2 is a second discharge coefficient, ε 2 is a second expansion factor, K 2 is a second fixed geometry factor proportional to the cross-sectional flow area of the fourth conduit, ΔP 2 is the second differential pressure, ρ is the mixture density of the multiphase fluid, g is the acceleration due to gravity, and h is the specified height.

6. The system of claim 5 , wherein the operations performed by the processor comprise comparing the first total mass flow rate of the multiphase fluid and the second total mass flow rate of the multiphase fluid to determine an adjustment of the first discharge coefficient (C d1 ) or an adjustment of the second discharge coefficient (C d2 ).

7. The system of claim 6 , wherein the first total mass flow rate (m T1 ) is equal to the second total mass flow rate (m T2 ), the mixture density of the multiphase fluid is a first mixture density of the multiphase fluid, and the operations performed by the processor comprise determining a second mixture density of the multiphase fluid at least based on a combined differential pressure equation:

ρ
2

=

Z
×
Δ
⁢

P
1

-

Δ
⁢

P
2

g
×

(

1
+
Z

)

,

wherein ρ 2 is the second mixture density of the multiphase fluid, ΔP 1 is the first differential pressure, ΔP 2 is the second differential pressure, g is the acceleration due to gravity, and Z is defined by:

Z
=

(

C

d
⁢
1

×

ε
1

×

K
1

C

d
⁢
2

×

ε
2

×

K
2

Assignees

• Saudi Arabian Oil Co

Inventors

• Ramakrishnan Vijay

Classifications

• G01F1/74 Primary

  Devices for measuring flow of a fluid or flow of a fluent solid material in suspension in another fluid · CPC title

• G01F1/34

  by measuring pressure or differential pressure · CPC title

• G01F1/372 Primary

  with electrical or electro-mechanical indication · CPC title