METHOD FOR DETERMINING EFFECTIVE HYDROGEN INDEX OF FLUIDS THAT FULLY OR PARTIALLY SATURATE PORE SPACE OF NATURALLY SATURATED ROCK SAMPLES Russian patent published in 2021 - IPC G01N33/24 G01N24/08 

FIELD: mining industry.

SUBSTANCE: invention relates to the determination of the characteristics of formation fluids simultaneously located in the pore space of a rock sample. When implementing the method, several naturally saturated samples of rock belonging to the same formation are selected, so that there are 2 samples per one place of collection. Samples from the first group are crushed and pieces larger than 3 mm in size are selected. The volume of the solid phase Vsol.ph.1_i is determined on each selected sample of crushed rock using a helium porosimeter. The apparent volume of pore fluids Vf.ap.1_i is determined by nuclear magnetic resonance (hereinafter – NMR) at HI=1. The crushed sample is placed in prepared cups made of a filter paper. The cups with the sample are placed in Soxhlet apparatuses for cleaning samples by extraction in an alcohol-benzene mixture. After the extraction, the sample cups are dried, desalted in distilled water if necessary, and re-dried, at a temperature of 105ºC. The volume of the solid phase Vsol.ph.2_i is determined using a helium porosimeter. The apparent volume of pore fluids Vf.ap.2_i is determined by NMR at HI=1. The true volume of fluids that occupied the pore space is calculated, according to a given mathematical dependence. Then the apparent volume of fluids, which occupied the pore space, is calculated at HI=1 according to a given mathematical dependence. Next, the effective hydrogen index of the fluids located in the pores of naturally saturated samples is calculated. The samples are then placed under a layer of fluid in the form of kerosene or a model of formation water and kept under vacuum until the release of air bubbles stops, after which the samples are placed in a saturator, where they are kept for at least 2 hours with an excess pressure of 15 MPa. The apparent coefficient of total porosity Cp_100app is determined by NMR at 100% filling of the pore space with fluids. The hydrogen index of the fluid HI_fl.sat with which the samples were saturated with is determined. The effective hydrogen index of all fluids in the pore space is calculated for samples in a naturally saturated state with pre-saturation with fluid, followed by the calculation of the true coefficient of total porosity of samples pre-saturated with kerosene.

EFFECT: increased information content and reliability of the definition is achieved.

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