US 12,436,014 B2
Metering method based on gas volume fraction fitting for wet natural gas
Yanzhi Pan, Shanghai (CN); Hailin Xue, Shanghai (CN); Yi Zhang, Shanghai (CN); Huamin Xiao, Shanghai (CN); and Xichun Liu, Shanghai (CN)
Assigned to Haimo Subsea Technology (Shanghai) co., Ltd., Shanghai (CN); and CNOOC CHINA LIMITED, SHANGHAI BRANCH, Shanghai (CN)
Appl. No. 18/694,431
Filed by Haimo Subsea Technology (Shanghai) co., Ltd., Shanghai (CN); and CNOOC CHINA LIMITED, SHANGHAI BRANCH, Shanghai (CN)
PCT Filed Apr. 20, 2023, PCT No. PCT/CN2023/089557
§ 371(c)(1), (2) Date Mar. 26, 2024,
PCT Pub. No. WO2024/093158, PCT Pub. Date May 10, 2024.
Claims priority of application No. 202211365421.5 (CN), filed on Nov. 3, 2022.
Prior Publication US 2025/0130087 A1, Apr. 24, 2025
Int. Cl. G01F 1/88 (2006.01); G01F 1/74 (2006.01)
CPC G01F 1/88 (2013.01) [G01F 1/74 (2013.01)] 12 Claims
OG exemplary drawing
 
1. A flow metering method based on gas volume fraction fitting for wet natural gas, being implemented according to the following steps:
step 1, acquiring a fitting array, wherein
the fitting array comprises some one-to-one corresponding data comprising a gas Froude number Frg, Venturi pressure loss PL, Venturi differential pressure DP1 and a gas volume fraction GVF;
step 2, fitting relationships between the gas Froude number Frg and the Venturi pressure loss PL and the Venturi differential pressure DP1 according to Formula (1) as follows:

OG Complex Work Unit Math
DP3=DP1−PL, and
a gas Froude number calculation formula is obtained by means of fitting;
step 3, setting a division range according to a data size of the gas Froude number Frg, and dividing the fitting array into three sections, namely a high Frg section, a medium Frg section and a low Frg section;
fitting, according to the section to which the fitting array belongs, relationships between the gas volume fraction GVF and the Venturi pressure loss PL and the Venturi differential pressure DP1 in sections, as shown in Formula group (2) as follows,

OG Complex Work Unit Math
wherein
x1, x2 are both natural numbers, x1<x2,
k=DP1/DP3, and
a piecewise gas volume fraction calculation formula is obtained by means of fitting;
step 4, acquiring a calculation array of wet gas to be measured, wherein
the calculation array comprises some one-to-one corresponding data comprising real-time Venturi pressure loss PLs, real-time Venturi differential pressure DP1s, a real-time gas phase density ρg, and a real-time liquid phase density ρl, wherein the method comprises measuring at least the real-time Venturi pressure loss PLs and the real-time Venturi differential pressure DP1s, with a Venturi flow meter,
a real-time ks value is calculated according to Formula (3) as follows:

OG Complex Work Unit Math
a real-time DP3s value is calculated according to Formula (4) as follows:

OG Complex Work Unit Math
step 5, calculating a real-time gas volume fraction GVFs, wherein
the real-time DPS value is plugged into the gas Froude number calculation formula obtained in step 2 to obtain a real-time gas Froude number Frgs, the three values of Frgs, x1 and x2 are compared, the section to which the calculation array belongs is determined by taking the division range set in step 3 as a standard, and
the real-time ks value is plugged into the corresponding section in the piecewise gas volume fraction calculation formula obtained in step 3 to calculate and obtain the real-time gas volume fraction GVFs; and
step 6, calculating a real-time mass flow rate Qtp according to Formula (5) as follows:

OG Complex Work Unit Math
wherein
C,E are both constants, d represents a diameter of the throat of the Venturi, and

OG Complex Work Unit Math