Tight gas reservoir starting pressure gradient determination method

A technology of starting pressure gradient and determining method, applied in measurement devices, suspension and porous material analysis, instruments, etc., can solve the problem of unable to characterize the starting pressure gradient of tight gas reservoirs

Active Publication Date: 2021-10-01
SOUTHWEST PETROLEUM UNIV
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Problems solved by technology

[0004] The purpose of the present invention is to overcome the deficiencies in the existing methods, provide a method for determining the start-up pressure gradient of tight gas reservoirs, and overcome the difficulty in the prior art that the start-up pressure gradient of tight gas reservoirs cannot be characterized by theoretical models

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  • Tight gas reservoir starting pressure gradient determination method
  • Tight gas reservoir starting pressure gradient determination method
  • Tight gas reservoir starting pressure gradient determination method

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Embodiment Construction

[0043] The present invention will be further described below in conjunction with the accompanying drawings.

[0044] Step 1. Taking a single capillary in a tight gas reservoir matrix as the research object, and considering the influence of interface capillary force and effective slip factors, a motion equation of the gas-liquid two-phase flow of the single capillary is established.

[0045] The expression of the capillary force at the two-phase interface is:

[0046]

[0047] In order to characterize the effective slip of the fluid flow in the capillary, the real slip length and the effective slip length are introduced.

[0048]

[0049] According to the force balance of gas-driven water flow combined with Newton's law of internal friction, the gas-liquid two-phase motion equation is established:

[0050]

[0051] In the formula: p c is the capillary force, MPa; l se is the effective slip length, nm; l sa is the apparent slip length, nm; l st is the real slip len...

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Abstract

The invention provides a tight gas reservoir starting pressure gradient determination method which comprises the following steps: taking a single capillary in a tight gas reservoir matrix as a research object, considering the influence of interface capillary force and effective slippage factors, and establishing a motion equation of gas-liquid two-phase flow of the single capillary; based on the established motion equation, obtaining a water-phase flow velocity equation and a water-phase flow equation of the single capillary, and carrying out scale upgrading through a fractal theory to obtain a water-phase flow equation of a rock core scale; and according to the water phase flow equation of the rock core scale, enabling the water phase flow to be made to be 0, and obtaining the corresponding starting pressure gradient through calculation. According to the method, the difficulty that the starting pressure gradient of the tight gas reservoir cannot be represented through a theoretical model in the prior art is overcome, so that the calculation of the starting pressure gradient is quicker and more accurate.

Description

Technical field: [0001] The invention relates to the field of petroleum and natural gas development, in particular to a method for determining the start-up pressure gradient of tight gas reservoirs. Background technique [0002] my country is rich in tight gas resources and has great development potential, which has become one of the most important areas for increasing natural gas reserves and production in my country. Compared with conventional oil and gas reservoirs, the matrix permeability of tight gas reservoirs is low, and hydraulic fracturing is required to obtain industrial productivity. [0003] Low-permeability tight gas layers have small pore throats, poor pore connectivity, high capillary resistance, and generally high water saturation. Gas seepage tends to produce unique seepage characteristics different from medium-high permeability gas reservoirs. Experiments show that when the water saturation of the core is greater than a certain limit value, the gas seepage...

Claims

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Application Information

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IPC IPC(8): G01N15/08
CPCG01N15/0826
Inventor 曾凡辉张涛郭建春王永红王道成
Owner SOUTHWEST PETROLEUM UNIV
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