CN107271323B - Real-time measuring instrument for hydrate decomposition gas - Google Patents

Abstract

The invention discloses a real-time measuring instrument for hydrate decomposition gas. The experimental device measures the gas release amount in the hydrate decomposition process in the rock core by using a drainage method. The device can control the temperature in the reactor to carry out an experiment, wherein hydrates in the rock core are decomposed, and the discharged water is measured by an electronic balance and is collected in real time by a data collector. And processing the data to draw a decomposition gas volume change curve and a decomposition gas release rate change curve with time in the process of decomposing the hydrate in the rock core. And obtaining the decomposed gas release amount after the decomposition is finished. And (4) breaking the core, releasing hydrate in the core, and measuring the total hydrate decomposition gas release amount in the core at the moment. The ratio of the value obtained by subtracting the two values to the total hydrate decomposition gas release amount is the specific gravity of the decomposition residue.

Description

A real-time measuring instrument for hydrate decomposition gas

technical field

The invention relates to the technical field of hydrate decomposition monitoring, and relates to a device that can measure the volume of decomposed gas in real time during the temperature-controlled decomposition of natural gas hydrate in the core and measure the residual amount of the decomposition gas in the core containing hydrate after decomposition.

Background technique

At present, people's attention to the exploitation of hydrates is gradually increasing, and understanding the decomposition status of hydrates to guide the exploitation of hydrates has become the focus of attention. The natural gas hydrate (combustible ice) in the Shenhu waters of the Pearl River Estuary of China was ignited for trial production on May 10, 2017. The initial production volume was large, but with time, the production volume declined rapidly. The first day of trial production There are 35,000 cubic meters of mining volume, but after 31 days of trial mining, the total gas production reaches 210,000 cubic meters, with an average daily output of 6,800 cubic meters. It is very important to actively carry out research on hydrate decomposition.

The research on the decomposition of hydrate in the core in the laboratory has guiding significance for the analysis of the decomposition of hydrate in the actual formation. At present, there is not enough research on the kinetics of hydrate decomposition. At present, the establishment of a model is generally used for qualitative analysis, and then the model parameters are calculated through experimental quantitative data for research. Quantitative measurement of decomposed data is generally carried out using instruments designed with complex sensor groups. Such instruments are complex and expensive, and this measurement method is not suitable for experimental research in general laboratories. In order to solve this problem, it is necessary to design an experimental instrument that can use general laboratory equipment, has a simple structure, is convenient to operate, and is economical and can be widely used in general experimental conditions. At the same time, it is found that there is no research on the measurement of the residual amount of hydrate decomposition in the core. The residual amount of decomposition has a certain guiding significance for the on-site recovery factor. Therefore, a device that can measure the residual amount of hydrate decomposition can be designed to measure this data. Analysis is important.

SUMMARY OF THE INVENTION

The problem to be solved by the present invention is to provide a real-time measuring instrument for hydrate decomposition gas which collects and measures the amount of hydrate decomposition gas by using the drainage method, aiming at the imperfection of existing facilities and technologies.

The technical scheme of the present invention is as follows:

An experimental method and device for measuring the volume of decomposed gas in real time. Hydrate decomposes in a closed space with constant pressure, and the volume of hydrate decreases. Due to the increase in the volume of gas in the space where decomposed gas is generated, the increase in gas volume is much greater than that of hydrate volume decomposition. Decreased amount, it is considered that the increase in the volume of gas in the space is the volume of hydrate decomposition gas. Water is added to the airtight connection chemical instrument to produce a reaction-drainage container with two phases of gas and water and a fixed volume. The gas-phase space is used as the reaction device and the interior is approximated as a constant-pressure closed space. The closed space can be separated by a valve to separate excess Water phase and gas phase, the separation state can open the reaction device and add the hydrate core to be tested. The reaction device is connected to the top of the drainage device, the pressure generated by the liquid column in the connected state has a suction effect on the reaction device, the hydrate is decomposed in it, the gas phase displaces the liquid phase downward, and the displaced water is discharged from the container, and the volume of the discharged water is equal to the space The gas increase volume is also equal to the hydrate decomposition gas volume. By collecting the variation law of the discharged water quality through the data acquisition system, the volume of water can be calculated by V=m/ρ, and the real-time volume of the decomposed gas can be obtained. The constant temperature water bath box provides the required constant temperature to the reaction device, and then the gas phase near the water phase condenses the produced gas to a uniform constant temperature for drainage. The top of the reaction device is connected to a container that can store the core-breaking liquid separated by a valve. After the normal decomposition is completed, the valve can be opened to inject the liquid into the reaction device by liquid gravity without changing the total volume of gas and liquid in the existing device. The internal residual hydrate continues to decompose, and the residual gas displaces the discharged water in the same way to measure the volume of the decomposed residual gas.

Description of drawings

FIG. 1 is a schematic structural diagram of a real-time measuring instrument for hydrate decomposition gas according to the present invention.

In the figure: 1—constant pressure separatory funnel; 2,3,8,14—valve; 4,7—bend joint with valve; 5—three-port opening reactor; 6—constant temperature water bath; 9,11,15—seal 10—condensing pipe; 12—bend joint; 13—pear-shaped separatory funnel; 16—drainage conduit; 17—beaker; 18—electronic balance; 19—data collector; 20—iron stand.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

Example 1 The principle and implementation steps of the measurement experiment of the hydrate decomposition gas volume using the drainage method

Close all valves before connecting the unit. Before connecting the device, put the core breaking liquid corresponding to the detected core in the constant pressure separatory funnel 1 and seal the top, and put enough water in the pear-shaped separatory funnel 13 . The three-port opening reactor 5 is composed of the upper three-port reactor cover and the lower barrel-shaped container. The barrel-shaped container is immersed in a constant temperature water bath 6 to control the temperature in the container. During injection, the core breaking liquid does not contact the reactor wall and falls vertically into the reactor, and the left and right sides are respectively connected with valve elbow joints 4 and valve elbow joints 7. The right valve elbow joint 7 and one end of the condenser pipe 10 are connected by a sealed conduit connector 9 to cool the gas phase of the right displacement water phase to a constant temperature. The other end of the condenser tube 10 is connected to the elbow joint with the same sealed conduit connector 11, the elbow joint 10 is connected to the upper interface of the pear-shaped separatory funnel 13, and the pear-shaped separatory funnel is fixed with the iron stand 20, and the gas phase is from top to bottom. Displace the liquid phase. The nozzle under the pear-shaped separatory funnel 13 is connected to the drain conduit 16 by the sealed conduit connector 15. The drain conduit 16 penetrates into the beaker 17, but does not touch the beaker 17. This is to prevent the draining water flow from causing the drain conduit 16 to vibrate and tap the beaker to affect the balance reading. In addition, the nozzle of the drainage conduit 16 cannot be too close to the bottom of the beaker 17, which is to prevent the nozzle of the drainage conduit 16 from being too close to the bottom of the beaker 10, and the impact of the water flow in the conduit opening on the bottom of the beaker 10 will affect the balance reading. The beaker is placed on the electronic balance 18, and the electronic balance 18 is connected to the data collector 19 for real-time data collection. Once the device is connected, the experiment is ready.

When carrying out the test, it is necessary to test the air tightness of the device first, and open the valve 8 and valve 14. At this time, the entire device has only one side of the drain conduit 16 under the pear-shaped separatory funnel to communicate with the outside world. The liquid column proves that the device connection is airtight. After checking the air tightness of the device, open the constant temperature water bath 6 to preheat the three-port opening reactor 5 for a period of time, and at the same time, the condensate begins to pass into the condenser tube 10 to remove the influence of temperature on the gas volume. Then open the valve 3 to make the drain conduit 16 be filled with the liquid column, and continue to discharge water until the liquid level in the beaker 17 has not passed the drain conduit 16 orifice and then close the valve 3. This is to prevent the drain conduit 16 orifice from hanging in the air at the beginning of the experiment, and the water flow in the air. Acceleration will shock the beaker 17 and affect the balance reading. In order to prevent excessive loss of water in the pear-shaped separatory funnel during the process of opening the three-port opening reactor 5 and putting it into the core to be tested, close the valve 3 and then close the valve 8. The electronic balance 18 was zero-adjusted, and then the three-port opening reactor 5 was opened to put the experimental hydrate-containing core. Immediately after closing the three-port opening reactor 5, open the valve 8, the device begins to drain water with the decomposition of hydrate, and the reading of the electronic balance 18 changes accordingly. The volume of water can be calculated by V=m/ρ to obtain the real-time volume of decomposed gas. When the balance reading no longer changes to prove the decomposition is complete, record the final reading as the maximum amount of decomposition gas. At this time, the valve 2 is opened so that the core breaking liquid in the constant pressure separatory funnel 1 flows into the three-port opening reactor 5, so that the core is broken and the residual hydrate is further decomposed into gas. Complete the core destruction, and record the balance reading as the total amount of decomposed gas after the balance reading is stable. Specific gravity of residual amount of decomposed gas=(total amount of decomposed gas-maximum amount of decomposed gas)/total amount of decomposed gas.

Claims (4)

1. A real-time measuring instrument for hydrate decomposition gas, mainly comprising: a core destruction device based on a constant pressure separatory funnel; a decomposition gas reaction device based on a three-port opening reactor, a constant temperature water bath box, and a condensation pipe; The drainage device is mainly composed of a separatory funnel and a beaker, and the data collection device is mainly composed of an electronic balance and a data collector. It is characterized in that: the bottom of the three-port open reactor is immersed in a constant temperature water bath, and the ambient temperature of hydrate decomposition is determined by the water bath temperature. Control, a condenser tube is connected between the three-port opening reactor and the pear-shaped separatory funnel to cool the gas displacing the water phase to a certain constant temperature, and the three-port opening reactor is connected to the top of the pear-shaped separatory funnel, and the gas phase displaces the liquid phase downward. , There is a beaker under the pear-shaped separatory funnel. The liquid in the pear-shaped separatory funnel can enter the beaker through the drainage conduit. The beaker is placed on the electronic balance. The data collector is connected to the electronic balance and collects the data measured by the electronic balance. The constant pressure separatory funnel of the liquid is connected above the three-port opening reactor, and the valve is opened, and the destructive liquid flows into the reaction device by gravity and contacts the core to destroy the core. The internal temperature is decomposed to generate gas to displace the water in the drainage device. After the decomposition, the core is destroyed by the core destruction device to drain the residual gas, and the data collection device completes the data collection. 2 . The real-time measuring instrument for hydrate decomposition gas according to claim 1 , wherein the volume of the water phase displaced by the gas phase in the drainage device is the volume of the decomposed gas. 3 . 3 . The real-time measuring instrument for hydrate decomposition gas according to claim 1 , wherein the displaced water is discharged, collected, weighed by a balance, and the volume is calculated by V=m/ρ. 4 . 4. The real-time measuring instrument for hydrate decomposition gas according to claim 1, characterized in that: the balance is connected to the data collector, the device continuously drains water, and the displayed value of the balance changes in real time, and the displayed value of the balance can be recorded in real time.

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