CN-119124294-B - Secondary separation flow measurement system based on small GLCC and ERT

Abstract

The application relates to the technical field of multiphase flow fluid measurement, in particular to a secondary separation flow measurement system based on small GLCC and ERT, which can solve the problems that the prior two methods have the defects of small flow measurement range, poor generalization capability and the like when being used independently, so that the method cannot adapt to complex and changeable flow conditions of an oilfield site, and the optimization of measurement results often needs complex data processing technology, so that the measurement is difficult and inaccurate. The system comprises a single-stage separator, a two-stage separator and a sensor, wherein the single-stage separator comprises a separation chamber, the separation chamber is of a cylinder type structure, an inlet of the separation chamber is connected with a system inlet, a liquid outlet of the separation chamber is connected with a system outlet, a gas outlet of the separation chamber is connected with the two-stage separator, the two-stage separator is based on a small GLCC design, the gas outlet and the liquid outlet of the two-stage separator are respectively connected with the system outlet, and the sensor comprises a flowmeter ERT.

Inventors

• LI DIE
• HU CHENJUN
• YU LING

Assignees

• 清华大学深圳国际研究生院

Dates

Publication Date

20260512

Application Date

20240712

Claims (6)

1. 1. A secondary separation flow measurement system based on small GLCC and ERT, comprising a single stage separator, a secondary separator and a sensor: The single-stage separator comprises a separation chamber, the separation chamber is of a cylinder type structure, the inlet of the separation chamber is connected with the system inlet, the liquid outlet of the separation chamber is connected with the system outlet, the gas outlet of the separation chamber is connected with the secondary separator, the secondary separator is designed based on a small GLCC, and the gas outlet and the liquid outlet of the secondary separator are respectively connected with the system outlet; The sensor includes a flowmeter and ERT; The inlet of the separation chamber is inclined, and the separation chamber is arranged in a circular shape with gradually smaller size; Correcting the result of the flowmeter by calculating the void fraction of the gas and the liquid by the ERT; the ERT corrects the flow meter results by calculating the void fraction of the gas-liquid, further comprising: Establishing a relation between the conductivity and the gray value of the reconstructed image by a proper image reconstruction method so as to visualize the conductivity distribution in the section of the pipeline; the measurement is corrected by calculating the void fraction.
2. 2. The small GLCC and ERT based secondary separation flow measurement system of claim 1, wherein the liquid outlet of the single stage separator is connected to the system outlet through a primary liquid line, the liquid outlet of the secondary separator is connected to the system outlet through a secondary liquid line, and the gas outlet of the secondary separator is connected to the system outlet through a gas line.
3. 3. The small GLCC and ERT based secondary split flow measurement system of claim 2, wherein sensors are installed on both the primary and secondary liquid lines.
4. 4. The small GLCC and ERT based two-stage separation flow measurement system of claim 1, wherein the system inlet is a tilted arrangement.
5. 5. The small GLCC and ERT based two-stage separation flow measurement system of claim 1, wherein the establishing of the relationship between conductivity and gray scale values of the reconstructed image by a suitable image reconstruction method to visualize conductivity distribution within a pipe section further comprises: Normalizing the voltage measurement, taking the measurement of the pipeline when the pipeline is full of water as high calibration, and the normalization formula is as follows: ; Where V n is the normalized voltage measurement, V m is the measured voltage data, and V w is the calibration data; the relationship between normalized voltage measurement and conductivity distribution is expressed as: ; Where S is the normalized sensitivity matrix, σ n is the normalized conductivity distribution, the negative sign indicates conductivity, and the direction of change of the measured value is opposite, assuming that the equivalent voltage V x is inversely proportional to the conductivity σ, x is: ; wherein, the equivalent conductivity is sigma m which is used as the input of the image reconstruction algorithm to obtain apparent conductivity distribution; the said And V w is measured with full water in the pipe, σ w /σ m is described as: ; Thus, the formula sum for calculating the volumetric flow rate of a liquid based on the Bernoulli equation is combined The calculation is as follows: ; Linear projection (LBP) was applied in ERT image reconstruction, the LBP algorithm is as follows: ; wherein g is the gray level of the reconstructed image, and can reflect the field conductivity distribution, and mu is a unit vector, namely mu= [1, 1, & 1] T.
6. 6. The small GLCC and ERT based two-stage separation flow measurement system of claim 5, wherein the correcting the measurement by calculating the void fraction further comprises: dividing the section of the pipeline into different units, and enabling the number of effective grids in the pipeline to be expressed as 'n'; The gray level of the "ith" grid is denoted as "x", which is equal to 0 if the grid is filled with air, where gvf=100%, and is equal to 1 if the grid is filled with water, where gvf=0%; Assuming that there is a linear relationship between void content of individual grids and gray level, when gvf=60%, gray level is 0.4, by summarizing gray, air content in the whole duct is obtained: 。

Description

Secondary separation flow measurement system based on small GLCC and ERT Technical Field The application relates to the technical field of multiphase flow fluid measurement, in particular to a secondary separation flow measurement system based on small GLCC and ERT. Background Multiphase flow is a phenomenon commonly existing in petrochemical industry, the phase refers to different physical properties or mechanical states of different physical states or the same physical state, substances in nature can be divided into gas phase, liquid phase and solid phase three phases according to different substance forms, in general, a fluid system with two or more substances and a clear interface is regarded as multiphase flow, for example, gas and water are two different substances which are incompatible and can have a clear interface when mixed together, so that a gas-water mixture can be regarded as one of gas-liquid two-phase flow, namely gas-water two-phase flow at normal temperature. In the field of oil exploitation, mainly rely on container type separators to handle the multiphase flow of oil gas water that produces from the wellhead, column whirl gas-liquid separator (gas-liquid cylindrical cyclone separator, abbreviated as GLCC) is a high-efficient gas-liquid separator, be applicable to the gas-liquid two-phase separation and the measurement of land oil gas field and marine oil gas platform, compared with container type separators, GLCC has simple structure, with low costs, small, easy installation and operation etc. apparent advantage, this makes GLCC stand out in numerous separators, be used in each big oil field extensively, especially in offshore oil gas platform, because space is limited, occupation area and weight of equipment need to consider, in this respect, GLCC has obvious advantage in comparison with traditional separator, consequently, have shown good application prospect in newly-built marine gas field project and in the aspect of the dilatation transformation of platform. Measurement of multiphase flow rates from oil recovery to transportation is very important. In petrochemical industry, two types of multiphase flow measurement methods are commonly used, namely separation measurement and non-separation measurement. The separation measurement is to send the multiphase flow into a gas-liquid separator to separate into two fluids, namely a gas phase flow and a liquid phase flow, and then to measure the flow velocity respectively by using a single-phase flowmeter. In this process, one of the most critical devices is the separator. The columnar cyclone gas-liquid separator (GLCC) has the advantages of small volume, high separation efficiency, easy installation and operation, and the like, and is widely applied in the petroleum industry. Non-separation measurement is another method of direct measurement of multiphase flow without separation, which does not require a separation device. Turbine flow meters, ultrasonic flow meters, electromagnetic flow meters, and the like are types of commonly used flow meters. In recent years, the electric tomography (ERT) technology has been widely used because of its advantages of visualization, non-contact, no flow field interference, little environmental impact, etc. ERT technology is a two-phase/multiphase flow measurement technology developed by combining computer application technology with modern detection technology, and can provide information about the flow characteristics of fluids, such as gas/solid, gas/liquid, and liquid/liquid. ERT technology has become a recognized measurement technology in process applications as an on-line measurement technology with the advantages of visualization, low cost, non-invasiveness, robustness, etc. However, in the separation measurement method, two factors affecting GLCC efficiency are liquid carrying capacity (LCO) and gas carrying capacity (GCU), a phenomenon in which liquid leaves from a gas outlet at the top of the separator following a gas flow during gas-liquid separation is called LCO, and a phenomenon in which gas follows liquid to the bottom of the separator is called GCU. In addition, when the liquid phase flow is smaller and the gas phase flow is larger, a plurality of gases are often mixed in the liquid phase flow generated by the separator, so that the differential pressure measured by the orifice plate flowmeter is larger, the flow measured by the flowmeter is larger than the actual flow, and a certain measurement error exists. For non-separation measurement, turbine flowmeter, ultrasonic flowmeter, electromagnetic flowmeter and other types are commonly used flowmeters, but the equipment is easy to be interfered by an external flow field, has large volume and higher requirements on installation and measurement space, and the image reconstruction effect in ERT technology is greatly influenced by the flow pattern of fluid. Therefore, the two methods have the defects of small flow measurement range, poor gener