SU1064187A1 - Mountain rock specimen porosity and penetrability determination device - Google Patents

Abstract

A DEVICE FOR DETERMINING THE POROSITY AND PERMEABILITY OF SAMPLES OF SAMPLES, containing a sealed sample holder, a rubber seal inserted into it, a compacting mechanism, vacuum systems and pressure measurement systems connected to the holder, and a gas supply and discharge system, and tea and gas that, in order to determine the porosity and permeability of samples of various sizes, the seal is made in the form of a rubber cup with a hole in the bottom, through which the movable hollow rod is passed, rigidly connected to I is a cylindrical base located inside the glass, and the mechanism (L clamping seal is made in the form of a piston, equipped with a screw clamp with a scale, the gas inlet and outlet systems are connected to a hole made in the piston and to a hollow rod. О) 4 00

Description

The invention relates to a technique for determining the physical properties of mountain rocks. A device for measuring porosity and skeleton volume of rock samples is known, comprising a sample chamber, an elastic sealant, gas switching elements, a pressure measurement system. The compactor in the B1 of the elastic bag separates the chamber into two parts, in one of which a sample is placed. The operation of the device is based on the principle of free expansion of gas with excess pressure when it is bypassed from one volume to another ij. The drawbacks of the device include the need to use samples with a grinded edge, as well as the impossibility of examining uncemented samples and determining permeability. The closest technical solution to the present invention is a device for determining the gas permeability of porous bodies, which contains a sealed sample holder, a rubber seal inserted into it, a mechanism for compressing the seal, vacuum system and pressure measurement connected to the holder, and gas supply and discharge systems: 2. The disadvantages of the device include the impossibility of determining the porosity, as well as the need to use samples of strictly specified geometrical dimensions. The purpose of the invention is to determine the porosity and permeability of samples of various sizes. The goal is achieved by the fact that, in a device for determining the porosity and permeability of rock samples, containing a sealed sample holder, a rubber seal inserted into it, a seal pressing mechanism, vacuum system and pressure measurement connected to the holder, and gas withdrawal, the expansion element is made in the form of a rubber cup with a hole in the day through which a movable hollow rod is passed, rigidly connected to a cylindrical base located; s inside the cup, - and the mechanism of the clamping seal is made in the form of a piston, equipped with a screw clamp with a scale, with the supply system and. The gas outlet is connected to the hole made in the piston, and to the hollow rod. The drawing shows a schematic diagram of the device. The device contains a sealed holder 1, a rubber gasket 2 inserted into it with a gap 3. Inside the cup is placed a cylindrical base 4 rigidly connected to the stem 5. The rod 5 is made with a cavity 6 that communicates with an annular groove 7, which is connected through a stop valve 8 with a gas flow meter consisting of a receiver 9 and a meter 10. A rock sample (core) 11 is mounted with an end on the base 4. On the other side of the holder 1, there is an upper piston 12 with a hole for connection to the gas lines, lowered and dnimaemy with a screw 13 rotated by the capstan 14. The position of the piston relative to the rubber cup 15 is controlled by a scale graduated in units of volume occupied by the piston in the holder 1. The sealing joint. the holder 1 with respect to the upper piston 12 and the base 16 is reached using rubber standard rings 17 and 18, and the rod 5 with the ring 19. The vacuum system and the pressure measurement system contain valves 20 and 21, which serve to fill the core holder with gas, the valve 22 to connect the core holder with a vacuum pump and a vacuum gauge 23 and a valve 24 with a measuring press 25 and a pressure gauge 26 having a movable pointer (arrow position lock) 27. The axis of the flywheel 28 of the press 25 is connected with gears from the press volume counters 29. Using valve 30, the device is connected to a source of gas (helium,: nitrogen, air) at a pressure of 3.5-4 atmospheres, and by means of a valve 31 with a vacuum pump. The determination of the porosity of the cemented and non-cemented rocks is carried out as follows. The core is pressed into the rubber cup and placed on the base 4. If sand is tested, it is poured into the glass so that its top is 56 mm below the top of the glass. The internal volume of the cup 2 with the inserted piston (without sample) is known. The total volume of the holes connecting the valve 8 to the lower end of the core and the valve 20 to the upper end is strictly constant. Due to the fact that the holes in the rod 5 move along with the rod for the length of the annular groove 7, their volume does not change with different sample lengths and different compression. After installing the core, assembling the holder 1 and inserting the piston 12 into the sleeve to a depth controlled by the scale 15, the cup 2 and the pores of the core are evacuated with open valves 2U, 22 and 31 and closed 8, 21, 30 and 24.

Vacuuming is performed within 2-3 minutes. Next, valves 20 and 22 are closed, and through valve 24 and 3.0, the system is filled with gas. The piston of the press 25 set to the position of maximum volume, the counter 29 is set to zero. The valve 30 is closed and the pointer 27 fixes the position of the gauge 26. The valve 20 is opened, after which part of the gas from the system enters the core holder, filling its free space and core pores, and the gauge 26 moves away from the previously fixed position by some angle.

By turning the flywheel 28, the press piston is moved in the direction of decreasing its volume until pressure in the system is restored, which is determined by combining the arrow of the pressure gauge 26 with the pointer 27. The reading from the counter 29 is determined and the volume of the solid core phase is determined by the formula

where U (silt is the volume of the solid phase of the skeleton core) the internal volume of the cup 2 with the piston 12 inserted (without sample); Ufp is the volume of holes connecting the end of the upper piston with the needle of the valve 20 (in the closed state) in total with the volume of the holes connecting the lower end of the core with the needles of the valves 8 and 21 (in the closed state);. U (is the volume read from counter 29.

Next, opening the valves 8 and 30, pr the closed valves 21 and 22, pass the gas core holder, observe the gas counter 10 and rotate the screw 13 using the driver 14, compress

the piston 12 of the wall and the bottom of the glass 2 until the gas flow through the counter 10 does not fall sharply. In this case, the following will occur: the piston 12 acts on the walls of the glass and through the sample and the base 4 on its bottom (narrows the inner diameter of the steel pipe). Since the Poisson's ratio is reactive (| U 0.48–0.49) is almost 0.5, the core is compressed by uniform all-round pressure.

The permeability coefficient of the sample is determined by

Rg

five

where 1 is the viscosity of the gas passed through the core;

I core length-,

average pressure in the core, Ppl cross-sectional area of the core J

0

Qy, is the gas flow rate through the pores of the core; Closing the valves 8, 24 and 30. And opening 22 and 31, again evacuate the core holder and the core in the compressed state 5 NI. In the described manner, the volume of air entering the pores of the core is determined by the counter 29, and the volume of the pore space is calculated by the formula

,R,

WITH

and then calculate the coefficient of porosity m by the formula

Ur

pore

m

five

  . The ability to determine porosity and permeability on a single instrument significantly increases the productivity of researchers.

0

The invention can be used in field laboratories engaged in testing cores extracted from boreholes to obtain a comprehensive description of rock formations, which will allow a more reliable assessment of reserves.

Claims (1)

DEVICE FOR DETERMINING 'POROSITY AND PERMEABILITY OF ROCK SAMPLES, containing a sealed sample holder, a rubber seal inserted into it, a seal clamping mechanism, vacuum and pressure measuring systems connected to the holder, and gas supply and exhaust systems, and scheesya in that, to determine the porosity and permeability of the samples of various sizes, the seal is designed as a rubber Vågå cup with a hole in the bottom, through ^- which is omitted movable hollow rod rigidly connected to the cylinder ndricheskim base located inside the cup, the seal and clamping mechanism is designed as a piston equipped with a screw clamp with a scale, the supply system and connected to a gas outlet opening provided in the piston, and the hollow stem. G '”ns V