RU2708847C1 - Device for sample preparation of core to determination of crack resistance - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention relates to mining, in particular to oil and gas industry, and concerns devices for core preparation in order to determine their crack resistance. Device for preparation of core sample for determination of crack resistance includes base with installed on it core placement device, measuring scales, wherein base is made in form of rectangle with two longitudinal parallel guides and is equipped with a ruler, wherein the guides are of rectangular shape. Besides, device for arrangement of core is made in form of fixed support, which rigidly fixed from one end of base, and movable support, wherein movable support is installed in longitudinal guides with possibility of movement along base, note here that bottom is provided with two neodymium magnets. On the basis there is a longitudinal groove into which there is an angle with measurement scales made with possibility of movement along the base length.

EFFECT: high operational and technical qualities of the device, which lead to higher efficiency and accuracy of preparation core to test.

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Description

The invention relates to mining, in particular to the oil and gas industry and relates to devices for core preparation in order to determine their fracture toughness.

A device for separating and fixing the core when disassembling a core projectile (patent RU No. 2516311, IPC ЕВВ 25/10, publ. 05/20/2014 in bull. No. 14), including the upper and lower parts, representing the upper and lower crimp clamps, respectively, when this upper crimp collar consists of links interconnected pivotally and is fixed to the core pipe using the upper screw-coupler and nut, the lower part of the device is made in the form of a screw that is contracted on the core surface with the lower screw-coupler and nut of the lower crimp clamp, co oyaschego of the profiled inside surface having links interconnected pivotally, on the side surfaces of which are provided with holes defined therein kernolomatelyami-screws, the lower clamp connected to the upper.

The disadvantages of this device are:

- firstly, the complexity of the design, due to the large number of parts nodes (crimp clamp with handles, screw-coupler with nut, knife-cutter, etc.);

- secondly, it is impossible to prepare the core before testing it for crack resistance, since this device does not allow marking of the core before cutting it;

- thirdly, it is impossible to reduce the consumption of core material during core preparation (a large amount of core material is wasted);

- fourthly, the poor quality of preparation of core material for the determination of crack resistance, since it is impossible to measure the height and angle of the sawn core, and the error (deviation from the right angle of 90 °) obtained when cutting the core can lead to erroneous results when calculating the value of crack resistance.

The closest in technical essence and the achieved result is a device for preparing a core sample for determining crack resistance, including a base with a device for core placement installed on it, measuring scales (a.s. SU No. 1696944, IPC G01N 3/00, publ. 07.12. 1991 in bull. No. 45). The basis of the device are limiters with supports mounted on them, made in the form of cylinders, and which are the basis for the placement of rigidly made end mandrels. Measuring scales are removable. The disadvantages of this device are:

- firstly, the complexity of the preparatory adjustment of the design, due to the large number of parts of rigid end mandrels;

- secondly, significant time spent on preparation for the test and on dismantling the installation at the end of the test, since each core sample must be fixed on both sides in the end mandrels, which reduces the performance of the device;

- thirdly, the poor quality of preparation of core material for the determination of crack resistance, since it is impossible to measure the height and angle of the sawn core, and the error (deviation from the right angle of 90 °) obtained when cutting the core can lead to erroneous results when calculating the value of crack resistance;

- fourthly, rigid fixation of the core ends in the end mandrels and their installation on the supports distorts the result of the crack propagation, which reduces the quality of the test.

The technical objectives of the invention are to increase the efficiency and accuracy of core preparation before testing for crack resistance by simplifying the setup of the device and reducing the time required to prepare for testing, improving the quality of preparation of core material for determining crack resistance, improving ease of use and reducing the time for preparing the core for testing , as well as improving the operational and technical qualities of the device.

The stated technical problems are solved by a device for preparing a core sample for determining crack resistance, including a base with a device for core placement installed on it, measuring scales.

What is new is that the base is made in the form of a rectangle with two longitudinal parallel guides and is equipped with a ruler, and the guides are made in a rectangular shape, the device for placing the core is made in the form of a fixed support, which is rigidly fixed from one end of the base, and a movable support, moreover, a movable support installed in longitudinal guides with the possibility of movement along the base, while the base is equipped with two neodymium magnets from below, a longitudinal groove is made on the base, in which the second inserted square with measuring scales and made with the possibility of movement along the length of the base.

In FIG. 1, 2 and 3 schematically depict the proposed device.

A device for preparing a core sample for determining crack resistance includes a fixed 1 (Fig. 1) and a movable 2 supports, base 3.

The base 3 is made in the form of a rectangle with two longitudinal parallel guides 4 and 5, made of a rectangular shape. The base 3 is equipped with a 6 'ruler and a 6' 'square (Figs. 1 and 3).

The fixed support 1 (see Fig. 1) is fixed rigidly from one end of the base 3, for example, using a threaded connection (not shown in Fig. 1-3). The movable support 2 (Fig. 1) is installed in the longitudinal guides 4 and 5. The movable support 2 from the bottom is equipped with a surface 7 (Fig. 1-2) that interacts with the base 3. Also, the base 3 from the bottom is equipped with neodymium magnets 8 'and 8' 'for fixation of the movable support 2 surface 7 to the base 3 at a distance - L from the fixed support 1.

The base 3 under the ruler is provided with a longitudinal groove 9, into which a square 6 ″ is inserted with the possibility of placement, fixation and movement of the outer protrusion 10 along the length of the base. The 6 '' square is equipped with a protractor 11 and an additional line 12.

The device operates as follows.

To prepare the core sample 13 for determining the fracture toughness, the fixed support 1 (Fig. 1 and 3) of the upper part of the device is rigidly attached to the base 3 of the lower part of the device using a threaded connection.

Next, in the base 3 of the lower part of the device in the longitudinal guides 4 and 5 establish a movable support 2 of the upper part of the device. The movable support 2 is moved by the surface 7 relative to the base 3 by a distance L from the fixed support 1.

The distance L is determined by the formula:

where L is the distance between the fixed 1 and movable 2 supports, mm;

S is the distance from the fixed 1 and movable 2 supports to the place of cut 14 of the core sample 13, mm

Fixed 1 and movable 2 supports should be located at the same distance S from the place of cutting 14 of the core sample 13, and the condition must be met:

where, R is the radius of the core sample, mm

We take the thickness of the core sample: t = 30 mm, the radius of the core sample: R = 34 mm, and the distance from the fixed 1 and moving 2 supports to the place where the 14 core sample was cut:

S = 20 mm.

For the correct installation of the movable support 2, a ruler 6 'is used on the base 3.

The core sample 13 is placed on a fixed 1 and movable 2 supports. The risk 15 on the fixed support 1 is set at the zero mark of the ruler 6 ', according to the risk 16 on the movable support 2 we set the mark L = 40 mm core sample 13. Then, in the longitudinal groove 9 of the base 3, the 6 ″ square equipped with the protractor 11 is inserted with the outer protrusion 10 and an additional ruler 12 and a risk 17. The square 6 '' is located at risk 17 at a distance of S = 20 mm from the zero mark on the ruler 6 on the basis of 3, according to formula 1:

L = 2⋅S = 2⋅20 mm = 40 mm.

The assembled equipment together with the core sample 13, with a thickness of t = 30 mm, is placed on the press base (not shown in Figs. 1-3) so that the place for cutting 14 of the core sample 13 is located at the same distance S from the fixed 1 and movable 2 supports.

Using the conveyor 11 of the square 6 '', we determine the angle of deviation of the cut 14 of the core sample 13, for example, the angle is 89.5 ° (not shown in Fig. 1-3) relative to the base 3 (Fig. 3), and according to the additional ruler 12 of the square 6 '' we determine the height h of the cut 14 of the core sample 13, for example, h = 15 mm, and after measuring the square 6 'is removed from the base 3.

The presence of a 6 'ruler and a 6' 'square with a protractor 11 and an additional ruler 12 makes it possible to determine the cut height 14 and the deviation of the cut angle 14. When the cut angle deviates from 90 ° at a given height (h = 15 mm) in more than 1 ° core sample 13 is rejected and not installed under the press, as this can lead to erroneous results when calculating the value of crack resistance. If the angle of cut 14 from 90 ° at a predetermined height (h = 15 mm) less than 1 °, the core sample 13 is installed under the press.

Next, the core is loaded using a press until it is destroyed, while the load P is fixed, at which the core was destroyed, for example, P = 2000 N.

After the test, the fracture toughness value of sample 1 is calculated using well-known methods, for example, proposed in “Fracture testing of a soft rock with semi-circular specimens under three-point loading” (IL Lim, IW Johnston, SK Choi, JN Boland, Fracture testing of a soft rock with semi-circular specimens under three-point loading, Part 1 - Mode I. Int J Rock Mech Min Sci, Vol. 31, 1994, pp. 185-97):

where K _IC is the value of crack resistance of the sample, MPa⋅m ^1/2 .

P _f - load at which the destruction of sample 10, N;

π - 3.14;

h - cut height 11, m;

Y _I - dimensionless stress intensity factor;

α is the dimensionless geometric coefficient;

R is the radius of the sample, m;

t is the thickness of the sample, m;

S is the distance from the cut 11 to one of the supports 1 or 2, m

Substituting the numerical values in the formulas (5, 4, 3), we obtain:

Thus, according to the results of testing on sample 1, the value of its crack resistance was determined: K _IC = 0.85 MPa⋅m ^1/2 .

A device for preparing a core sample for determining crack resistance has a simple design, since components and parts that are difficult to manufacture are excluded from the design, which will make it possible to reduce the cost of manufacturing the device, as well as reduce metal consumption and weight without losing the efficiency of the device.

The device allows the core to be prepared before it is tested for crack resistance, namely, to mark the core before sawing it, which is of paramount importance for obtaining the exact value of the load before its destruction.

When conducting tests using this device, a core sample 13 of a semi-cylindrical shape is used, which allows to reduce the consumption of core material during core preparation.

The use of this device improves the quality of preparation of core material for determining fracture toughness, because after sawing a core sample, it allows you to measure the height and angle of the sawn core, and, based on the measurement results, reject core samples that exceed the permissible error, which can lead to erroneous results when calculating the fracture toughness value.

The device for preparing a core sample for determining crack resistance has a simple design and allows you to:

- to prepare the core before testing it for crack resistance;

- reduce the consumption of core material in the preparation of core;

- to improve the quality of preparation of core material for the determination of crack resistance.

The device provides an increase in the efficiency and accuracy of core preparation before testing for crack resistance by simplifying the setup of the device and reducing the time required to prepare for testing, improving the quality of preparation of core material for determining crack resistance, improving ease of use and reducing the time for preparing the core for testing, and also improving the operational and technical qualities of the device.

Claims (1)

A device for preparing a core sample for determining crack resistance, including a base with a device for placing core on it, measuring scales, characterized in that the base is made in the form of a rectangle with two longitudinal parallel guides and is equipped with a ruler, and the guides are made in a rectangular shape, a device for placement the core is made in the form of a fixed support, which is rigidly fixed from one end of the base, and a movable support, and the movable support is installed in ln guides with the possibility of movement along the base, while the base from the bottom is equipped with two neodymium magnets, a longitudinal groove is made on the base, into which a square with measuring scales is inserted and made to move along the length of the base.

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