SU721736A1 - Method of determining open porosity of ore-collectors - Google Patents

Description

one

The invention relates to the field of studying samples of oil-bearing rocks and is intended for use and exploration, the calculation of oil reserves and the development of oil fields,

A known method for determining the open porosity of reservoir rocks (Preobrazhensky method) 1, in which a sample is extracted, dried, saturated with liquid, then the sample is weighed in air to saturation, after Sddeni, and, after saturation with liquid, it is weighed in the same liquid , and calculate the open porosity by the volume of the fluid entering the pores and the sample volume.

This method is very long, so to determine the open porosity of the sample, it is necessary to spend at least 30 minutes. In addition, this method gives a significant error in determining the porosity of the sludge. As is known, during the drilling of wells due to the complexity and laboriousness of coring, its number is very limited and does not sufficiently characterize the section of the reservoir. In order to obtain the missing data, sludge is used, which is small pieces of rock, for example, 3x4x5 mm in size, produced by drilling wells. The slime samples can be used to characterize the formation at the gsoboy point of the incision.

The closest to the proposed technical essence is the method of determining open porosity

0 collector rocks by the method of nuclear magnetic resonance (NMR) 2, which includes the following operations: sample of rock rock extractor {dried, saturated under vacuum with hydrogen-containing liquid ,. the amplitude of the induction signal from this liquid is measured, the volume of the sample is measured, and the porosity is calculated from the pore volume and sample. NMR instrument, with

By means of which the pore volume is determined, it is pre-calibrated with a known amount of the same hydrogen-containing liquid. The time for determination of open porosity by the indicated method is shortened by 3 times as compared with the Preobrazhensky method.

However, rock samples (core, as well as sludge samples) have closed pores, in some part of these

0 then contains a liquid, due to which distortions are introduced into the results of the determination of open porosity by NMR. The presence of volume of closed pores introduces an error in the determined value of open porosity.

The aim of the invention is to improve the accuracy of determining the open porosity of reservoir rocks.

The goal is achieved by the fact that in the method of determining the open porosity of reservoir rocks using NMR, including sample extraction, drying, saturation under vacuum with hydrogen containing a liquid, measuring the amplitude of the induction signal from a saturating liquid, and calculating the open porosity taking into account the amplitude of the calibration signal, additionally measuring the amplitude of the induction signal from the reference sample after its saturation, hydrogen-containing liquid, the amplitude of the induction signal from the test sample after its drying and determine the open porosity (Kpo) by the formula

V, (Rev.),

K - s

e and v, p

reference volumes

where and test specimens;

TO

E 1-1 amplitude of the induction signal from the reference sample after saturating it in odorods with the containing liquid;

the amplitude of the induction signal from the sample under study after saturating it with a hydrogen-containing liquid;

 the amplitude of the induction signal from the sample after drying

moreover, as reference samples use samples that do not have closed pores.

An example of the proposed method.

198 samples were taken for testing, of which 143 were represented by limestone and 55 by sandstone. The length of the samples was 22 mm and the diameter was 6-8 mm. In addition, collector rock slurry consisting of 4-5 pieces of 3x4x5 mm was tested.

The method was carried out as follows.

In each experiment, the sample was extracted with toluene, then dried to constant weight. Then, using a minispec R-20 coherent spectrometer, the signal was measured

induction from the dry sample, the maximum magnetic field generated by the spectrometer being 4.69 kG at a frequency of 20 MHz. The amplitude of the signal was observed on the oscilloscope screen and measured with a digital volmeter with an error of no more than 0.3%.

Then, the sample under investigation was saturated under vacuum with a hydrogen-containing liquid — kerosene, and the volume of the sample was measured. The sample volume was found by changing the level of liquid kerosene - in a calibrated tube after the sample was immersed. The level was monitored using a KM-8 cathetometer. Then the induction signal from the EO pulse from the saturated sample was measured using a spectrometer, the amplitude of the signal was measured Do also using a digital voltmeter.

The open porosity () of each sample was determined by the above formula.

A sample with no closed pores was taken as a reference for all experiments, i.e. it was a dry sample that lacked an NMR induction signal.

Nowadays, dermal magnetic logging is widely used in well surveying. The proposed method allows to make a correction, determined in laboratory conditions, by the value of closed pores, specifying the open porosity value, using directly the data of magnetic magnetic logging, which will allow more accurate analysis of geophysical data, more accurately calculate oil reserves. oil reserves at the exploration stage

Claims (2)

1. Himatudinov Sh.K. Physics of oil and gas reservoir., M., Nedra, 1971, p.309. 2. Vedenin S.V. et al. Studying some of the reservoir properties of rocks by the NMR. Geology of oil and gas 1972: 12, p.59-63 (prototype).