METHOD OF QUANTITATIVE DETERMINATION FOR DIFFERENT WATER-SATURATION PHASES OF ROCK BY THERMAL MASSOMETRY Russian patent published in 2013 - IPC G01N5/02 

FIELD: oil and gas industry.

SUBSTANCE: rock sample is extracted from oil, desalinated and dried at 105°C, cooled and weighed in dry condition; its porosity and permeability is determined and thereafter the sample is saturated with distilled water under suction; then total water content is found for the same by difference in weight before and after saturation. The sample is subject to thermal massometry survey which includes drying of the sample at constant temperature of 60°C and automatic registration of drying kinetics till complete water dehydratation in 30 sec. Thermal massometry data of the sample weight change is analysed for drying process due to water evaporation. Drying curve Ao is being plotted; the curve reflects decrease of water content of the sample due to evaporation. It is converted into differential Bo and integral Co curves of gradients for evaporated water variation in time in drying process. Using curves Ao, Bo, Co and data of rated quantity of water saturation the curve A is being plotted for the sample drying; this curve reflects variation in quantity of water in the sample in relation to pore volume of the sample. Curve of differential gradient B and curve of integral gradient C for evaporated water are being plotted in relation to pore volume of the sample. A combined graph of curves A, B, C is being plotted. At curves B and C reference points are specified which reflect sequence of water dehydratation dynamics in drying process and correspond to boundaries between different water phases and namely: between free water FRw and film water Fw, between film water Fw and loosely-bound LBw, between loosely-bound LBw and adsorbed water Aw, between adsorbed water Aw and crystallisation water Cw. Quantity of free phase of water FRw is defined against the leg of curve A that corresponds to the most intensive dehydratation of the sample and identified from the initial 100% water saturation up to the point corresponding to the first minimum water saturation in the curve B projected to the curve A; quantity of film water Fw is defined against the leg of curve A that corresponds to completion of the sample intensive dehydratation and identified from the point corresponding to the first minimum water saturation in the curve B projected to the curve A up to the point of maximum water saturation in the curve C projected to the curve A; quantity of loosely-bound phase of water LBw is defined against the leg of curve A that corresponds to commencement of the sample dehydratation slowing down and identified from the point corresponding to the first maximum water saturation in the curve B projected to the curve A up to the point corresponding to the second minimum water saturation in the curve B projected to the curve A; quantity of adsorbed water phase Aw is defined against the leg of curve A that corresponds to sharp slowing down of the sample dehydratation and identified from the point corresponding to the second minimum water saturation in the curve B projected to the curve A up to the point of commencement of water saturation curve A reaching asymptote; quantity of crystallised water phase Cw is defined against the leg of curve A that corresponds to completion of the sample dehydratation and identified from the point of commencement of water saturation curve A reaching asymptote to zero value of water saturation in the curve A.

EFFECT: reliable definition of different phases for water saturating the sample.

2 dwg, 2 tbl