Abstract: For determining a water cut of an oil-water mixture produced from an oil well at least one Venturi tube is placed in a well, through which an oil-water mixture, produced from a selected well segment, enters the borehole. During production process, pressure at a Venturi tube inlet and in a Venturi tube throat are measured, and flow temperature of the produced oil-water mixture at the Venturi tube inlet and the temperature of the Venturi tube wall in the Venturi tube throat are measured. Based on the results of the pressure and temperature measurements, the water cut of the oil-water mixture produced from the selected well segment is determined.

Abstract: In order to predict properties of a formation in a near-wellbore area exposed to a drilling mud rheological properties of the drilling mud, of a filtrate of the drilling mud and of a reservoir fluid are determined. Properties of an external mudcake, porosity and permeability of the core sample are determined. A mathematical model of the external mudcake is created. The drilling mud is injected through a core sample and dynamics of pressure drop across the sample and dynamics of a flow rate of a liquid leaving the sample are determined. Using an X-ray micro Computed Tomography a profile of concentration of particles of the drilling mud penetrated into the sample is determined. A mathematical model is developed for the internal mudcake to describe dynamics of changes in concentration of the particles of the drilling mud in a pore space of the core sample.

Abstract: A suspension of a contaminant comprising at least one solid component and colored with at least one cationic dye is prepared. The suspension is injected through a sample of the porous medium and the sample is then split. A distribution and a profile of the contaminant in the sample is determined on the basis of a distribution and an intensity of the at least one cationic dye.

Abstract: A porous medium sample is initially saturated with a conductive fluid, or a conductive fluid and a non-conductive fluid at the same time, or a non-conductive fluid only. Measurements of electrical resistivity are taken in at least two places along the porous medium sample, and a flooding experiment is carried out with a contaminant solution injected through the porous medium sample. During or after the filtration experiment, second measurements of resistivity are carried out at the same places where the first measurement had been made. Measured data are used for computing a profile of rock saturation with filtrate and a ratio of a modified porosity to an initial porosity of the sample.

Abstract: A suspension of a contaminant comprising at least one solid component and colored with at least one cationic dye is prepared. The suspension is injected through a sample of the porous medium and the sample is then split. A distribution and a profile of the contaminant in the sample is determined on the basis of a distribution and an intensity of the at least one cationic dye.

Abstract: A core sample is taken from a wall of a borehole and at least one core fragment is cut from the core sample. The irradiation of the core fragments is carried out with longitudinal acoustic waves and a propagation velocity of the longitudinal acoustic waves in each of the core fragments is measured. An empirical relationship between a velocity of a longitudinal acoustic wave and a porosity for a given lithological type of the rock is selected. A porosity for each core fragment is determined using the measured velocities of the longitudinal acoustic wave and the selected empirical relationship. A value for porosity change is determined by comparing the determined porosity values for the core fragments and a value of a reference porosity typical for the given lithological type of the rock.

Abstract: A source and a receiver of acoustic waves are placed on opposite surfaces of a porous medium sample. A first irradiation of at least one part of the sample with longitudinal acoustic waves is carried out. A propagation velocity of the longitudinal acoustic waves is determined. An empirical relationship between a propagation velocity of a longitudinal acoustic wave and a porosity for a given type of the porous medium based on the porosity and a saturation behavior of the sample is selected. A filtration experiment by injecting a contaminant mud through the sample is carried out. A second irradiation of the same portion of the sample with longitudinal acoustic waves is performed and a propagation velocity of the longitudinal acoustic waves is measured. A porosity change in this part of the sample is determined based on the velocities of the longitudinal acoustic waves measured prior to and after the injection of the contaminant and using the selected empirical relationship.

Abstract: A method for determination of a spatial distribution and concentration of contrast components in a porous sample comprises the steps of scanning a sample with X-ray and obtaining a computer tomographic image of the sample. Then an area of interest inside the obtained computer tomographic image is selected and a first cross-section of the computer tomographic image is defined. Spatial distribution and concentration of contrast components inside the area of interest are determined by analyzing histograms of grayness distribution in the cross-sections of the computer tomographic image starting with the reference cross-section.

Abstract: In order to predict properties of a formation in a near-wellbore area exposed to a drilling mud rheological properties of the drilling mud, of a filtrate of the drilling mud and of a reservoir fluid are determined. Properties of an external mudcake, porosity and permeability of the core sample are determined. A mathematical model of the external mudcake is created. The drilling mud is injected through a core sample and dynamics of pressure drop across the sample and dynamics of a flow rate of a liquid leaving the sample are determined. Using an X-ray micro Computed Tomography a profile of concentration of particles of the drilling mud penetrated into the sample is determined. A mathematical model is developed for the internal mudcake to describe dynamics of changes in concentration of the particles of the drilling mud in a pore space of the core sample.

Abstract: A method for determination of a spatial distribution and concentration of contrast components in a porous sample comprises the steps of scanning a sample with X-ray and obtaining a computer tomographic image of the sample. Then an area of interest inside the obtained computer tomographic image is selected and a first cross-section of the computer tomographic image is defined. Spatial distribution and concentration of contrast components inside the area of interest are determined by analyzing histograms of grayness distribution in the cross-sections of the computer tomographic image starting with the reference cross-section.

Abstract: A water-soluble salt of a metal with a high atomic weight is selected as an X-ray contrast substance providing a selective ion-exchange reaction with a clay. The salt has a general formula R+M?, where R+ is selected from a group consisting of Ba2+; Sr2+; Tl+; Rb+ . . . , and M? is selected from a group consisting of Cln; NOn; OHn; CH3COO, SO4; . . . . The X-ray contrast substance is injected into a core sample. Upon completion of the selective ion exchange reaction a non-contrast displacing agent is injected into the sample. The sample is scanned by computer X-ray microtomography. An area of interest and a reference cross-section are selected at the obtained computer tomography image. Grayscale histograms in cross-sections of the sample are obtained. Spatial distribution and concentration of the clay is estimated by means of histograms analysis starting from the reference cross-section histogram.

Abstract: A water-soluble salt of a metal with a high atomic weight is selected as an X-ray contrast substance providing a selective ion-exchange reaction with a clay. The salt has a general formula R+M?, where R? is selected from a group consisting of Ba2+; Sr2+; Tl+; Rb+ . . . , and M? is selected from a group consisting of Cln; NOn; OHn; CH3COO, SO4; . . . in accordance with a standard table of inorganic substances' water solubility. The X-ray contrast substance is injected into a core sample. Upon completion of the selective ion exchange reaction a non-contrast displacing agent is injected into the sample. The sample is scanned by computer X-ray microtomography and an image of the sample is obtained. An area of interest and a reference cross-section are selected at the obtained computer tomography image. Grayscale histograms in cross-sections of the sample are obtained.