Device and method for joint measurement of pores and permeability of tight rock under formation pressure

Abstract

The invention discloses a compact rock pore-permeability joint measurement device and method under formation pressure. Acquisition device; the high-pressure gas source is connected to the inlet end of the variable volume pressure chamber; the variable volume pressure chamber is connected to the pressure monitoring device, and the outlet end of the variable volume pressure chamber is connected to the core holder The inlet end of the holder is connected; the core holder is connected with the confining pressure pump, the temperature monitoring device, and the pressure difference monitoring device; the outlet end of the core holder is connected with the vacuum pump; the variable volume pressure A chamber and the core holder are disposed within the thermostat. The invention can determine the dead volume of the joint measurement device, preferably the volume of the variable volume pressure chamber, and can simultaneously measure the porosity and permeability of the target rock core under formation pressure through the pressure decay curve.

Description

technical field [0001] The invention relates to the technical field of measuring rock porosity and permeability, in particular to a device and method for combined measurement of pores and permeability of tight rocks under formation pressure. Background technique [0002] The porosity and permeability of reservoir rocks are important properties for understanding and studying reservoirs. Porosity is an important parameter to quantitatively describe the storage capacity of rocks. It refers to the ratio of the pore volume in rocks (or the volume of spaces in rocks not filled by solid matter) to the total volume of rocks. Permeability indicates the property that rocks allow fluid to pass under a certain pressure difference, and the permeability of the reservoir is expressed by permeability. With the extraction of underground oil and gas, oil and gas fluids will be extracted from the ground, the pore fluid pressure in the reservoir rock will decrease, and the reservoir rock will ...

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Problems solved by technology

[0004] (1) The existing methods do not directly measure the porosity and permeability of reservoir rocks under formation conditions, which are indirect methods for determining the porosity and permeability of reservoir rocks. Some scholars have proved that the equivalent porosity and permeability values ​​calculated by the existing methods do not have Representative under stratigraphic conditions (Xiao Wenlian et al., 2019)

[0005] (2) At present, most of the existing rock sample porosity and permeability testing equipment need to test the porosity and permeability separately, or test step by step in the same equipment, and have not achieved simultaneous and accurate measurement; There may be unstable factors such as micro-cracks in the rock, and it is difficult to ensure the consistency of the rock properties during the test in separate tests or step-by-step tests, resulting in that the tested rocks are not in the same condition.

[0006] (3) During the experiment, different test schemes, equipment maintenance, etc. may cause changes in the volume of pipelines and valves, which will affect the test results, and often require dead volume calibration and correction in time

[0007] (4) The permeability of tight rocks is very low, generally the conventional steady-state method (He Gengsheng et al., 2011) cannot be used to measure the permeability, and the pressure pulse method is usually used to measure the permeability; the pressure pulse method is currently used In general, the volume of the pressure chamber in the test instrument is usually fixed or selected based on experience. However, the actual volume of the variable pressure chamber will affect the pulse pressure decay curve, resulting in errors in test results.

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