Device and method for automatic detection of hydrocarbon diffusion coefficient in rock under high temperature and high pressure

Abstract

The present invention provides a device and method for automatic detection of hydrocarbon diffusion coefficient in rocks under high temperature and high pressure, wherein the device includes: a first high pressure chamber, a first low pressure chamber, a first pneumatic actuator, a second pneumatic actuator, Second high-pressure chamber, second low-pressure chamber, third pneumatic actuator, fourth pneumatic actuator, first automatic six-way valve, second automatic six-way valve, gas chromatograph detector, left diffusion chamber and right diffusion chamber. The measuring device can realize automatic gas extraction, thereby solving the technical problems of cumbersome operation and inaccurate diffusion coefficient measurement in the prior art, and achieving the technical effect of effectively providing the accuracy of the diffusion coefficient measurement result.

Description

technical field [0001] The invention relates to the technical field of oil and gas exploration, in particular to a device and method for automatic detection of hydrocarbon diffusion coefficients in rocks under high temperature and high pressure. Background technique [0002] Diffusion refers to a physical process in which gas molecules migrate freely from high-concentration areas through various media to low-concentration areas to reach equilibrium under the action of concentration gradients of hydrocarbon gases. Diffusion is one of the important mechanisms of oil and gas migration. It plays an important role in the migration, accumulation, and formation of oil and gas, especially natural gas (because natural gas has small molecules, light weight, and strong mobility, so it has strong diffusibility underground). Hiding, preserving and destroying play a vital role. [0003] For the accumulated oil and gas reservoirs, in addition to the sealing ability of the caprock itself a...

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Problems solved by technology

[0006] However, considering that both hydrocarbon gases and nitrogen have a certain solubility in water, the method of drainage and gas extraction may cause the change in the concentration of hydrocarbon gases to be undetectable in the initial stage of diffusion, thereby delaying the start time of diffusion and resulting in a smaller value of the final diffusion coefficient; However, due to the small amount of gas required for chromatographic detection, manual control of the valve to take gas may easily lead to a large amount of gas intake, which will cause a large pressure loss in the diffusion chamber and fail to meet the requirements of the experimental conditions.

Furthermore, the artificial control method will also cause the pressure imbalance of the two diffusion chambers, which will cause the gas to break through the sample through the pressure difference instead of diffusing through the concentration difference, thus making the measurement results larger

In addition, the manual control method requires the operator to take air every once in a while, which not only has a large workload, but also easily brings certain analysis errors due to manual operation.

[0007] For the technical problem of inaccurately determined diffusion coefficients mentioned above, no effective solution has been proposed so far, so it is necessary to modify the existing equipment to overcome the limitations of the device

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