Black shale soluble salt extracting method

Abstract

The invention discloses a black shale soluble salt extracting method which comprises the following steps: (1) preparing black shale into a centimeter-level block sample in any shape; (2) utilizing a vacuum drying box to dry the sample and weighing; (3) adding distilled water and an organic reducing agent acetone oxime into a container to make a water solution be in strong reducing environment (anEh value is lower than -200mV); (4) completely immersing the shale block sample into the water solution in the step (3) and utilizing an oxidizing and reducing potentiometer and a conductivity meter to respectively monitor the Eh value and conductivity of the water solution in real time; (5) controlling the adding amount of the acetone oxime in an extracting experiment process to make the water solution keep the strong reducing environment (the Eh value is smaller than -200mV); (6) obtaining an extracting solution containing the black shale soluble salt when a conductivity value of the water solution does not increase any more. By means of the black shale soluble salt extracting method disclosed by the invention, mineral oxidization and dissolution in a soluble salt extracting process areeffectively avoided, and the soluble salt is prevented from being lost in a sample preparing process; thus, accurate black shale soluble salt ion composition data can be obtained.

Description

technical field [0001] The invention relates to a core analysis method in the technical field of oil and natural gas exploitation, in particular to an experimental method for leaching soluble salts from black shale. Background technique [0002] Formation water has been in contact with oil and gas reservoir rocks for a long time. Under the conditions of high temperature and high pressure in oil and gas reservoirs, various minerals in rocks (such as feldspar, calcite, dolomite, clay minerals, etc.) undergo dissolution and phase transformation, resulting in the formation water containing various metal salts Classes, such as potassium salt, sodium salt, calcium salt, magnesium salt, etc., so the formation water is also called brine. Formation water salinity (that is, salt content) represents the sum of anion and cation contents in water, and the unit is mg / L or ppm. The salinity of formation water in rocks in oil and gas reservoirs varies greatly, ranging from thousands, tens ...

AI Technical Summary

Problems solved by technology

[0011] The purpose of the present invention is to overcome the shortcomings of existing methods such as easy oxidation and corrosion of minerals in the leaching process, easy loss of soluble salts in the sample preparation process, and unscientific leaching time setting, and propose a method for leaching soluble salts of black shale. method, this method selects centimeter-scale massive shale samples, uses organic reducing agents to keep the leaching solvent (i.e. distilled water) in an anaerobic state, and monitors the conductivity of the leaching solution to determine the leaching time reasonably, and can accurately obtain the The leaching solution of black shale soluble salt ensures the accurate evaluation of the ion type and content of shale gas reservoir formation water

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