RU2281393C1 - Method for fractured zone boundary determination in underworked rock massif - Google Patents

Abstract

FIELD: methods of underground or surface mining, particularly to determine fractured zone boundary determination without mine ventilation disturbance.

SUBSTANCE: method involves drilling upward hole from developing entry towards goaf space in several stages along with isolating hole interval under test at each stage and recording hole interval depth; installing partition made as annular diaphragm on hollow drilling tool end at well head; communicating the drilling tool with mine compressed air system through diaphragm and reducer and leaving it at rest; determining air pressure difference inside and outside hole interval by measuring pressure upstream and downstream of annular diaphragm under different pressure values of air flow to be supplied via the reducer; determining air flow velocity at well head from above pressure difference and annular diaphragm orifice diameter; plotting side and upper fracture zone boundaries.

EFFECT: increased safety of mining operations.

2 dwg

Description

The invention relates to the mining industry and can be used to determine the boundaries of the zone communicating with the worked out space of cracks. These boundaries are used to determine the conditions for safe mining at flooded workings and water bodies, as well as for the effective degassing of adjacent formations and mined space.

There is a method of determining the height of the zone communicating with the worked-out space of cracks in nature by monitoring the pressure of water in open piezometers (Recommendations for determining safe conditions for the extraction of suite formations under water objects. L .: Publishing house VNIMI, 1987, p. 26-38) .

The disadvantage of these methods is their limited ability to determine the parameters of the zone of cracks. They make it possible to determine only one parameter of the crack zone — its upper boundary, i.e. height.

There is also a method of determining the boundaries of the zone communicating with the worked-out space of cracks, including interval drilling of an upright well from a well into an array, sealing its mouth, installing an easily-ventilated ventilation bridge in the production, isolating a test interval with a sealant, measuring the speed and difference of air pressure in the well between the well head and the worked-out space and plotting along the length of the well of graphs of the speed of movement and pressure difference with a mark of the depth of the well, etc. wherein there is a change velocity and the pressure difference (Ed. St. №1634803, IPC E 21 F 7/00, publ. 15.03.1991 g). In this case, the pressure drop during installation of the jumper is created due to the mine depression.

The disadvantage of this method is that it involves a violation of the ventilation mode of the working face and adjacent workings for the duration of measurements of the speed and difference of air pressure, which is undesirable, because violates safety precautions.

The objective of the invention is to provide the ability to determine the boundaries of the zone of cracks without violating the ventilation mode of the face and adjacent preparatory workings.

To achieve the required technical result in the known method, which includes phased drilling of an upright well from the preparatory development towards the worked out space, isolating the tested interval of the well at each stage, fixing its depth, installing a jumper on the end of the hollow drill at the wellhead and determining the difference between air pressure in the interval and air pressure outside the interval, determining the air velocity through the wellhead and graphical construction of the upper and side It is proposed to use an annular diaphragm as a jumper for the new boundaries of the sin zones, and connect the hollow drill through the annular diaphragm and gear to the shaft compressed air system and withstand it. It is proposed to determine the air pressure difference by measuring pressures immediately in front of and behind the annular diaphragm at different pressures of the air supplied through the pressure reducer, and determine the air velocity through the wellhead by the indicated pressure difference and hole diameter of the ring diagram.

The use of pressure in the shaft compressed air system and the installation of a jumper in the form of a diaphragm directly at the wellhead eliminates the need to overlap the cross-section of the preparatory workings for the time of measurement and does not violate the ventilation mode of the working face provided for by the mining technology.

The method is illustrated by drawings, where Fig. 1 shows a vertical section through a well and graphs of the speed of movement and the difference in air pressure in the well, and Fig. 2 is the same, for example.

In the drawings, the following notation:

1 - rising well;

2 - a niche;

3 - preparatory development, located in the coal pillar;

4 - coal pillar;

5 - worked out space;

6 - zone of cracks;

7 - the upper boundary of the zone of cracks;

8 - lateral border of the zone of cracks;

9 - sealant;

10 - isolated interval;

11 - hollow shell;

12 - jumper in the form of an annular diaphragm;

13 - gear;

14 - manometer;

15 - mine system of compressed air;

16 is a point on the graph corresponding to the depth of the well L ₁ , at which there was a significant increase in speed and pressure difference;

17 is a point on the graph corresponding to the depth of the well L ₂ , at which there was a decrease in the speed and pressure difference to the initial values (close to zero);

18 - the edge of the reservoir.

The rising well 1 (Fig. 1) is drilled intervalwise from the niche 2 of the preparatory mine 3 located in the rear pillar 4 between the mine 3 and the mined-out space 5, in the direction of the mined-out space, over which a zone of cracks 6 communicating with the mined-out space is formed from the upper 7 and lateral 8 borders. The pressure difference and air velocity (calculation) is determined during drilling breaks after installing a sealant 9 in the well (tampon, gland or packer), with which the tested interval 10 is isolated from the rest of the well.

At the end of the hollow projectile 11 near the wellhead 1, a jumper 12 is installed in the form of an annular diaphragm or nozzle and the projectile is connected through a reducer 13 with a manometer 14 to the shaft compressed air system 15 used when drilling to purge the well.

To measure the pressure drop and air velocity through the hollow shell 11 and the tested interval, manometers are used that are connected to the hollow shell directly in front of and behind the annular diaphragm (jumper 12). The pressure drop can also be directly measured by a differential pressure gauge or a corresponding depressiometer. The speed of movement (or the amount of air passed through the annular diaphragm per unit time) is calculated according to the methodology (see Yamshchikov BC, Shkuratnik VL, Process Control during Underground Gasification of Coal. Study Guide: MGI, 1985, p. 73) taking into account the measured pressure drop, the diameter of the projectile (internal) and the diameter of the hole of the annular diaphragm, i.e. relative section of the diaphragm. The time to determine the flow rate or air velocity at a steady pressure drop is measured by a stopwatch.

At the same time, testing is carried out after 3-5 m of well drilling without violating the ventilation mode of the working face and adjacent preparatory workings. Measurements are made at different air pressures supplied through a pressure reducer 13 to a test interval 10 of the well.

According to the measurement results, graphs are built on which the depth of the well is plotted on one axis, and the velocity V, m / s of air through the annular diaphragm in the interval under test and cracks (if any) and the pressure difference in front and behind the annular diaphragm ( jumper 12) ΔР, Pa. According to the graphs ΔР and V, the depth L _{1 of the} well is determined, which is determined based on the position of the interval at which an increase in the speed of movement and the pressure difference is noted, and the depth L ₂ , where the above parameters are again reduced to zero. Marked in the section, the depths of the wells L ₁ and L ₂ give the position of points 16 and 17, respectively, on the lateral 8 and upper 7 boundaries of the zone of water-supply cracks. Having drawn a straight line through point 16 and edge 18 of the formation, a lateral boundary 8 is obtained, and through point 17 a line parallel to the bedding plane, the upper boundary 7.

The invention is as follows. The coal seam at the Tentekskaya mine in the Karaganda coal basin was mined by long pillars under the flooded workings of an overlying previously worked seam. In order to establish the lateral (from the fall side) and upper boundaries of the zone of cracks in front of the working face from the niche 2 of the ventilation Bremsberg 3, a well 1 was drilled, rising at an angle of 52 ° to the horizon 1. The next 5-meter interval under test was isolated. 10 using a sealant 9, connecting a hollow drill through an annular diaphragm (jumper 12) and a gearbox 13 to a shaft system 15 of compressed air and measuring with a differential pressure gauge hell pressure in annular diaphragms at different pressure levels, measured by manometer 14 and an adjustable gear 13. After the measurements from the system was disconnected and the ring gear aperture, and the recovered dock continued drilling of the next 5-m interval, after which the measurements were repeated. Each isolated test interval of the well was first filled with compressed air for 3 minutes, then the differential pressure was measured at the annular diaphragm and the measurement time was recorded. From the tested intervals 10, not related to the crack zone, the air did not go into the rock mass, the pressure in them (after a 3-minute pause) became equal to the pressure behind the gearbox, so the pressure drop in front of and behind the annular diaphragm (respectively, the speed calculated from it movement) was zero.

In the tested intervals, which were located in the zone of cracks, the air through the cracks went into the worked-out space, therefore a pressure differential arose at the diaphragm, which was recorded by a differential pressure gauge. In this case, the entire air flow passed through the annular diaphragm into the interval under test and through cracks into the mined-out space associated with the mine atmosphere.

On a vertical section along the axis of the well, graphs of the results of measuring the pressure difference ΔP at the annular diaphragm and calculated (by the difference in pressure and relative aperture of the diaphragm) velocities of air V through a hollow shell were calculated. According to the graphs, well depths L ₁ and L ₂ corresponding to the tested intervals were noted, where in the first case there was a significant increase in the difference in pressure and speed, and in the second, they decreased to zero after 3-minute pauses necessary to equalize the air pressure before an annular diaphragm and in the test interval 10. These points in the section gave the position of the lateral 8 and upper 7 boundaries of the zone of cracks corresponding to the worked out space, respectively. Graphic construction established the upper boundary of the zone at a distance of 85 m from the soil of the reservoir, and the lateral from the fall side - at an angle of 72 ° to the horizon. The graphs of V and ΔP versus well length shown in FIG. 2 were obtained at a pressure of 0.3 MPa. At a pressure of 1.5 MPa, the graphs are similar to those shown (not shown in the drawing).

Thus, as a result of measurements, the lateral and upper boundaries of the zone communicating with the worked-out space of cracks were established without violating the ventilation mode of the face and workings adjacent to it.

The advantage of the proposed method is the provision of the possibility of taking measurements without violating the ventilation mode of the workings.

The economic effect of the use of the method is due to the reduction of downtime due to the need to normalize its gas regime.

The invention is intended to be used in determining safe mining conditions for flooded workings and the rational location of wells for the degassing of adjacent formations.

Claims (1)

The method of determining the boundaries of the fracture zone in the undermined rock mass, including phased drilling of an upright well from the development towards the developed space, isolating the tested interval of the well at each stage, fixing its depth, installing a jumper at the end of the hollow drill at the wellhead and determining the difference between air pressure in the interval and air pressure outside the interval, determining the air velocity through the wellhead and graphical construction of the upper and the boundary of the crack zones, characterized in that an annular diaphragm is used as a jumper, and a hollow drill through an annular diaphragm and a reducer is connected to a shaft compressed air system and maintained, the specified air pressure difference is determined by measuring pressures immediately before and behind the annular diaphragm at different the pressure supplied through the air reducer, the air velocity through the wellhead is determined by the specified pressure drop and the hole diameter of the ring diagram .

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