Method for measuring overburden porosity with water in permeation fluid mechanics experiment

Abstract

The invention discloses a method for measuring overburden porosity with water in permeation fluid mechanics experiment. The method comprises the following steps of: adding ambient pressure around the core with known pore volume; injecting the single-phase fluid with known compression coefficients into the core in a saturated manner, and enabling pressure at the two ends of the core to conform to the actual conditions of the stratum; and then, sequentially increasing the ambient pressure, and sequentially measuring the change of pore pressure in the core after the ambient pressure is increased so as to determine the change of pore volume and determine the porosity change under an overburden condition. The measuring method disclosed by the invention is applicable to the overburden porosity research in the field of low-permeability and ultralow-permeability storage layer stress sensitive research; and the method can realize overburden porosity research on rock while simulating the overburden pressure on a real storage layer, pore pressure and real fluid parameters. The test equipment adopted by the method is simple, and the test principle is clear; and compared with the method for measuring overburden porosity with air, the effective porosity measured by the method disclosed by the invention can better reflect the overburden porosity characteristics of the real storage layer, and quantitative research on the overburden porosity of the storage layer can be realized.

Description

technical field [0001] The invention relates to a method for measuring core porosity in the petroleum geological industry, in particular to a method for measuring overburden porosity by water measurement in seepage mechanics experiments. Background technique [0002] At present, in the core analysis test work in the petroleum geology industry, the gas measurement method is usually used to study the overburden pressure porosity and permeability characteristics of the core; the experimental medium generally uses helium or nitrogen to measure the corresponding core gas porosity; the test principle is based on wave Boyle's law to determine the pore volume of rock samples. [0003] Such as image 3 Shown is the schematic diagram of the existing measurement of the pore volume of rock samples. The standard air chamber is a known volume V k The air chamber, the core is placed in the core chamber (core holder), the core is wrapped by a rubber sleeve and the confining pressure is ap...

AI Technical Summary

Problems solved by technology

In general, for the conventional overburden porosity test by gas measurement, the gas source pressure of the gas measurement overburden porosity measurement device is not too high, which cannot simulate the pressure of the fluid in the pores under the real reservoir, so under this condition The overburden porosity data obtained from the test cannot truly reflect the real situation of the formation porosity changing with the overburden pressure, and cannot simulate the fluid pressure of the real reservoir. The relationship between the overburden pressure and porosity obtained under this condition The overburden porosity relationship with the actual formation has a large deviation, and can only qualitatively describe the porosity and stress sensitivity characteristics of the reservoir

[0009] Therefore, the existing overburden porosity measurement method by gas measurement restricts the in-depth development of experimental quantitative research on the stress-sensitive characteristics of reservoirs, and the experimental results can only be used for qualitative research, which limits the application of experimental data

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