RU2207545C2 - Method of determination of oil saturation coefficient of core sample - Google Patents

Abstract

FIELD: methods of determination of oil saturation coefficient of core sample; field and scientific laboratories; oil geology work; outlook of regions. SUBSTANCE: proposed method includes extraction of oil-forming compounds from core sample; specimen of core sample is placed in weighing bottle with ground cover and carbon tetrachloride ((CCl₄)) of definite amount is poured in said bottle ; mixture is held for no more than 24 hours, after which extract is studied by infra-red spectroscopy or infra-red photometry and oil saturation coefficient is determined from the following relationship:

, where S is core sample oil saturation coefficient, %;

is mass fraction of hydrocarbons extracted from core sample and contained in extractive reagent (CCl₄), where

is volume of extractive reagent (carbon tetrachloride), l; ρ is oil density, g/cu cm; V_n is volume of pore space of core sample, cu cm. EFFECT: reduction of time required for performing study; enhanced accuracy of measurements.

Description

 The invention relates to a method for determining the coefficient of oil saturation of cores, which can be used in field and research laboratories, exploration units of oil and gas enterprises when performing exploration, geological exploration for oil and gas, when assessing the prospects of the region, as well as to solve other applied geological problems, in particular, the solution of hydrocarbon migration in reservoir conditions.

A known method for determining the oil saturation of the core, which uses the extraction-distillation method [1], based on the long-term extraction of hydrocarbons from the core by placing the core in a stream of hot toluene, drying the extracted core in an oven at a temperature of 100 ^o C, repeatedly weighing to obtain a constant weight extracted core sample, determination of the difference between the masses of the original and extracted, dried core samples, the mass of extracted hydrocarbons adjusted for the water contained in this sample. As you can see, the determination of the hydrocarbon content in the core sample in order to determine its oil saturation in a known manner is a lengthy procedure with the consumption of a significant amount of extractant, and also requires an additional determination of the water content in it. In this case, the accuracy of determining the mass of hydrocarbons in the core turns out to depend on the accuracy of determining the water content in it, which can introduce a significant error at low water concentrations in the core and, in addition, is an additional procedure that also increases the time for determining the oil saturation of the core material.

 The objective of the invention is to reduce the time to conduct research while maintaining the necessary measurement accuracy.

где S - коэффициент нефтенасыщенности керна, %;

- массовая доля углеводородов, экстрагированных из керна и находящихся в экстрагенте (ССl₄), г/л;

- объем экстрагента (четыреххлористого углерода), л;
ρ - плотность нефти, г/см³;
V_n - объем порового пространства керна, см³.The problem in the method for determining the oil saturation coefficient of cores is solved by extracting oil-forming compounds from the core, while the core sample is placed in a bottle with a ground cap, into which a fixed volume of carbon tetrachloride is poured, the mixture is kept for no more than a day, and the obtained extractant is examined by infrared spectroscopy or infrared photometry, and the oil saturation of the core is determined from the following relationship:

where S is the coefficient of oil saturation of the core,%;

- mass fraction of hydrocarbons extracted from the core and located in the extractant (CCl ₄ ), g / l;

- volume of extractant (carbon tetrachloride), l;
ρ is the density of oil, g / cm ³ ;
V _n - the volume of the pore space of the core, cm ³ .

Вышеприведенные существенные отличительные признаки нам были неизвестны из патентной и научно-технической информации и соответствуют критерию "Новизна".Salient features in the claimed invention are:
- the core sample is placed in a bottle with a ground lid, into which a fixed volume of carbon tetrachloride (CCl ₄ ) is poured;
- maintain the mixture for no more than a day;
- the obtained extractant is examined by infrared spectroscopy or infrared photometry;
- oil saturation of the core is determined from the dependence

The above significant distinguishing features were unknown to us from the patent and scientific and technical information and meet the criterion of "Novelty."

 Significant distinguishing features are not obvious to the average specialist in this industry, which meets the criterion of "Inventive step".

 The claimed invention has successfully passed the test in the sector of spectral studies, which allows us to conclude in accordance with its criterion of "Industrial applicability".

 The claimed method of determining the coefficient of oil saturation of the cores is carried out in the following sequence.

где S - коэффициент нефтенасыщенности керна, %;

- массовая доля углеводородов, экстрагированных из керна и находящихся в экстрагенте (ССl₄), г/л;

- объем экстрагента (четыреххлористого углерода), л;
ρ - плотность нефти, г/см³;
V_n - объем порового пространства керна, см³.The test core sample is placed in a bottle with a ground cap into which a fixed volume of carbon tetrachloride (CCl ₄ ) is poured. For the complete extraction of hydrocarbons from the core, the mixture is kept for no more than a day. After that, the extract obtained is examined by infrared (IR) spectroscopy and infrared (IR) photometry, and the coefficient of oil saturation of the core is determined from the following relationship:

where S is the coefficient of oil saturation of the core,%;

- mass fraction of hydrocarbons extracted from the core and located in the extractant (CCl ₄ ), g / l;

- volume of extractant (carbon tetrachloride), l;
ρ is the density of oil, g / cm ³ ;
V _n - the volume of the pore space of the core, cm ³ .

в CCl₄, которое оказалось равным 3,29 г/л. Для экстрагирования использовался объем CCl₄ Vэ=13,3 мл = 0,0133 л. Было известно, что плотность нефти ρ=0,8936 г/см³, а объем порового пространства испытуемого образца керна V_n=0,190 см³. После подстановки данных выполняется расчет коэффициента нефтенасыщенности керна по формуле

Заявленное изобретение в сравнении с прототипом позволяет сократить время на исследование и получить необходимую точность измерений.Definition Example
After daily core extraction, the absorption spectrum of the extract was measured using a LAFS-02I laboratory Fourier spectrometer in the region of 2700-3200 cm ^-1 in a cuvette with an absorbing layer thickness of 0.0998 cm. The content of petroleum hydrocarbons extracted from the core was determined from the optical density spectrum of the extract

in CCl ₄ , which was found to be 3.29 g / L. For extraction, a volume of CCl ₄ Ve = 13.3 ml = 0.0133 L was used. It was known that the density of oil was ρ = 0.8936 g / cm ³ and the pore volume of the test core sample was V _n = 0.190 cm ³ . After data substitution, the core oil saturation coefficient is calculated using the formula

The claimed invention in comparison with the prototype allows to reduce the time for research and to obtain the necessary measurement accuracy.

Sourse of information
1. Methodological recommendations for the study of reservoir rocks of oil and gas by physical and petrographic methods. - M .: VNIGNI, 1978.- 396 p. (prototype).

Claims (1)

A method for determining the oil saturation coefficient of a core, including extraction of oil-forming compounds from the core, characterized in that the core sample is placed in a box with a ground lid, into which a fixed volume of carbon tetrachloride is poured, the mixture is kept for 24 hours, after which the obtained extract is examined by infrared spectroscopy or infrared photometry, the obtained spectrum or the optical density of the extract determines the content of petroleum hydrocarbons extracted from the core

and the oil saturation of the core is determined by the formula

where S is the coefficient of oil saturation,%;

- mass fraction of hydrocarbons extracted from the core and located in the extractant (CCl ₄ ), g / l;

- volume of extractant (carbon tetrachloride), l;
ρ is the density of oil, g / cm ³ ;
V _n - the volume of the pore space of the core, cm ³ .