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Test system and method of fluid non-linear percolation characteristics in low-permeability porous media

A technique for porous media and characteristic testing, which is applied in the fields of suspension and porous material analysis, measuring devices, permeability/surface area analysis, etc. Long time and other problems, to achieve the effect of ensuring accuracy and stability, saving experimental testing time, and small changes

Active Publication Date: 2013-10-16
PETROCHINA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The inventor found in the process of realizing the present invention that the ring pressure loaded on the rock core increases with the increase of temperature, and the phenomenon is more obvious, because the time required for each experimental point test of the low-permeability rock core is relatively long , so if the external temperature fluctuates greatly, the micro-flow rate of the tested fluid will change greatly, which will bring a lot of inconvenience to the measurement of the nonlinear seepage characteristic curve

Method used

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  • Test system and method of fluid non-linear percolation characteristics in low-permeability porous media
  • Test system and method of fluid non-linear percolation characteristics in low-permeability porous media
  • Test system and method of fluid non-linear percolation characteristics in low-permeability porous media

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0047] Example 1: Discrete Data Measurements at High Displacement Pressures

[0048] Wash the core to be tested, dry it, and saturate the simulated formation water in advance;

[0049] Before the experiment starts, all valves are closed;

[0050] Fill the intermediate container 6 with simulated formation water, place the prepared core in the core holder 17, open the valves 15, 16, 19, and use the ring pressure pump 20 to load the core in the core holder 17 with ring pressure, Monitor the ring pressure value from the ring pressure gauge 14 until it reaches the standard, and then close the valves 16 and 19;

[0051] According to the experimental needs, a pressure value is initially set for the pressure reducing valve 2, and then an accurate experimental pressure value is set through the high-precision gas pressure-stabilizing valve 4;

[0052] Open the valves 3 and 8 to make the process smooth, and after confirming that there is no leakage, remove the possible air for the core...

Embodiment 2

[0059] Example 2: Discrete Data Measurements at Low Displacement Pressures

[0060] Wash the core to be tested with oil in advance, dry it, and saturate it with simulated formation water;

[0061] Before the experiment started, all valves were closed;

[0062] Place the prepared rock core in the core holder 17, open the valves 15, 16, 19, use the ring pressure pump 20 to load the ring pressure on the rock core in the core holder 17, and monitor the ring pressure value from the ring pressure gauge 14 , until the standard is reached, close the valves 16 and 19;

[0063] According to the needs of the experiment, open the required one of the valves 9g, 9h, 9i, 9j, such as the valve 9j, at this time, ensure that the other valves 9g, 9h, 9i are closed, start the peristaltic pump 9f, at this time, the constant pressure pipe 9e constant water overflow;

[0064] Open the valve 12 to make the low-range pressure sensor 11 effective;

[0065] Observe whether the process is unimpeded, ...

Embodiment 3

[0072] Example 3: Non-linear Curve Drawing

[0073] Using a series of pressure, displacement and time values ​​measured in Example 1 and Example 2, and using data processing tools, the relationship curve of "flow velocity-pressure gradient" can be drawn. Specifically, in the "flow rate-pressure gradient" relationship curve, since the opening pressure of the glass thin tube of the photoelectric micro-flowmeter 18 is atmospheric pressure, the pressure gradient is equal to the ratio of the reading of the high-range pressure sensor 10 or low pressure sensor 11 to the length of the rock core ,which is:

[0074] grad P = P L

[0075] gradP is the pressure gradient (unit: MPa / m); P is the reading of the high-range pressure sensor 10 or the low pressure sensor 11 (unit: MPa); L is the core length (unit: m). The flow velocity is equal to the ratio of the fluid volume in the glass capillary 18a whose length is...

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Abstract

The invention provides a test system and method of fluid non-linear percolation characteristics in a low-permeability porous media. The test system comprises a plurality of test branches, wherein, each test branch comprises a displacement pressure output unit for providing different pressures to transfer displacing fluid to a test core, a pressure measuring unit for the pressure of the displacingfluid output by the displacement pressure output unit, a flowing unit for accommodating the test core and providing ring crush to the test core, a flow measuring unit for measuring the flow of the displacing fluid flowing through the test core, and a thermostatically control unit for providing a constant ambient temperature for the flowing unit and the flow measuring unit. By adopting the thermostatically control unit, the influence of variation in temperature to the test results is eliminated, so that the test results are accurate.

Description

technical field [0001] The invention relates to the technical field of testing fluid flow laws in porous media, in particular to a testing system and method for nonlinear seepage characteristics of fluid in low-permeability porous media. Background technique [0002] Due to the complex pore structure and strong solid-liquid interaction in low-permeability porous media, the fluid inside it no longer obeys the classic Darcy's law during low-speed flow, but presents nonlinear seepage characteristics. figure 1 It is a schematic diagram of a typical non-linear seepage curve of a fluid in a low-permeability porous medium, which exhibits two obvious features, namely: there is a start-up pressure gradient (point A) and a nonlinear seepage section (section AD). For the study of these two characteristics, the most commonly used method is the steady-state method, that is, the "pressure difference-flow method". The quasi-linear section (DE section) measured by this method is relatively ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N15/08
Inventor 杨正明熊生春刘学伟张亚蒲何英王学武齐亚东
Owner PETROCHINA CO LTD
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