SU1553680A1 - Method of control of solid roof - Google Patents

Abstract

The invention can be used in the development of stratal deposits for the management of hard-to-damage roofs (TK). The goal is to create a controlled process of changing the strength and structural properties of the TC and increasing the efficiency of crack formation. The process of softening TC is carried out in three stages. At the first stage, the well (C) is located outside the zone of the reference rock pressure of the clearing hole (OGDOZ). The rock mass is preliminarily moistened and the torpedo 8 is subsequently detonated in a high viscosity fluid. In the second stage, C is in the OGDOZ zone. The injection of HPI is performed according to the specified parameters. In the third stage, C is located in the zone of maximum OGDOZ. The HPV is injected with surfactant additives until the liquid breaks through the cracks into the cleared area of the clearing slab, after which the TC is softened to the next C during the working out of the paw. 7 il.

Description

The invention relates to the mining industry and can be used in the development of stratum deposits to control hard-to-collapse roofs.

The aim of the invention is to create a controlled process of changing the strength and structural properties of roof rocks and to increase the efficiency of cracking by eliminating the degree of crack opening under the influence of the reference rock pressure on the penetration of fluid into the roof rocks.

Fig. 1 shows the layout of a well in an extraction column of lava, a plan view; Figure 2 is the same in the zone of influence of the reference rock pressure; fig. 3 - the same, in the zone of maximum reference pressure; figure 4 - section aa in figure 1; figure 5 is a section bB in figure 2; figure 6 - section bb In fig.Z; Fig. 7 shows a diagram of the displacements of the stress profile of the reference rock pressure with respect to the well as it moves downward.

The method is carried out as follows.

When developing stratum deposits with hard-to-collapse roofs or when clearing the bottom zones of the seamy rock pressure below the pillars from the outlined production of 1 borehole 2, crossing the main roof rocks along the length of the clearing hole 3. The well 2 is drilled in the first case through the required collapse step roofs, in the second - to the stress concentration zone under (above) all the pillars. After completion of drilling, the wellhead 2 is cased with pipes and sealed with sand-cement cement.

Prior to the start of blasting operations, the roof rocks are pre-moistened. In the borehole 2, nearest to the clearing face 3, a fluid, for example water, is injected with a high-pressure unit 4. Injection parameters are monitored using a pressure gauge 5 and a flow meter 6, which is equipped with a high-pressure installation 4. Water is pumped from the mine reservoir 7. At the end of the pre-moistening of the roof rocks, the well water is drained and sent to a predetermined depth torpedo 8,

0 5

0

, 45

five

0

five

BB. After that, the wellhead is sealed with an anti-shock attachment and, through a high-pressure installation, a fluid of higher viscosity is injected into the well than with the fluid being injected when the roof rocks are moistened, from the tank 9, where it is pre-stirred to a certain consistency. When pumping a fluid of increased viscosity, the hose from the mine reservoir is silenced. After the well is filled with a fluid of higher viscosity, a torpedo blast is produced, and the blasting is performed outside zone 10 of the reference rock pressure of the clearing face.

In this case, the pores and cracks of the array around the well in the radial fracture zone 11 are blocked, which prevents the free drainage of water previously pumped when the roof rocks are moistened back into the well. In addition, an increased viscosity fluid under the influence of

Due to the wedging effect of the fluid itself, the size of the explosives, penetrating into the pores and fractures of the array, and affecting the previously injected water, displaces it deep into the array, thereby significantly increasing the induced fracture zone 12 (microcracking) around the well.

As the mine clearing moves, the well enters zone 13 of the ever increasing reference rock pressure. In order to keep the cracks in zone 11 created by the explosion and hydraulic fracturing in the opened state and to continue the process of the formation of new cracks in zone 12, further injection fluid of high viscosity into the well is produced, while simultaneously monitoring the pressure of the pressure gauge and the flow rate of the fluid - claws flow meter. In the process of injection of well-tested viscosity fluid into the well, the parameters of fluid injection change as the filtration properties of the array change. Thus, when the pressure in the well, which occurs at the time of the opening of new cracks, increases, the permeability of the mass increases, then, to maintain the proppant effect of the increased viscosity fluid on the walls of the cracks, the flow rate and pressure of the fluid increase. With signs of hydraulic fracturing — a sharp increase in the injection pressure and a decrease in fluid flow occurring at the moment of filling all the cracks with liquid, the high-pressure installation is turned off, and the formation of new cracks and the further opening of the existing cracks occurs not only due to the viscous fluid, but and due to the creation in the well of a constant backwater, compensating for the ever-increasing rock pressure. As a result, there is a further expansion of zones 11 and 12 of radial and induced cracks around the well to more significant distances.

At the moment when the well reaches the zone 14 of the maximum reference pressure of the clearing hole, the cracking process fades out, since the openness and rate of formation of cracks decreases due to the effect of increased rock pressure. In order to continue the process of crack formation, even in the zone of increased rock pressure, surfactant additives are added to the viscous fluid being injected to increase its fluidity in order to penetrate it into smaller pores and fractures of the massif.

A fluid with surfactant additives that penetrates into cracks formed in its end parts, reduces the surface stress, contributes to the opening and growth rate of new cracks with a lower discharge pressure gradient. In addition, lubricating the surface of cracks with a viscous fluid drastically reduces the friction angle at their contact, reduces the adhesion force between the blocks and the splitting cracks, which positively affects the movement of the rock blocks. When cracks tend to close under the effect of increased rock pressure, the fluid of increased viscosity, concentrating in the unevenness of the planes of cracks and delaminations, slows down and prevents the cracks from completely closing. At the same time, a fluid of increased viscosity, which has a greater dynamic viscosity than water, does not practically squeeze out when the injection pressure drops towards the well, as may occur at the initial stage of processing.

roof, and wedging cracks, retains water. With an increase in the pressure gradient, the fluid of increased viscosity, having already increased flowability due to the addition of surfactants, penetrates into smaller pores and cracks not only of the array as a whole, but also inside the block of rocks itself, thereby violating its continuity and increasing its stratification.

As the radius of fracture increases under the influence of injection and the influence of the reference rock pressure, as well as the well reaches the maximum 14 zone of the reference rock pressure at the time the hole passes through the hole, the number and extent of fractures increases and, accordingly, the filtration properties of the massif. In addition, the magnitude of the opening of cracks is influenced by the degree of displacement of blocks of rocks relative to each other, which occurs when tensile forces are applied when a well enters the zone of active displacements. Therefore, to wedge the cracks formed by displacing the rock blocks and keep them open, they increase the flow rate and pressure of the injected fluid while simultaneously increasing its viscosity, i.e., surfactant additives are ceased to inject the fluid. Injection of a fluid of increased viscosity, without the addition of surfactants, is continued until a sharp steady pressure drop in the well occurs, resulting from the breakthrough of fluid through cracks into the exhausted well space. Thereupon, the process of weakening of the hard-to-collapse roof at the closest well to the bottom hole is stopped, the equipment is dismantled, except for stop valves at the wellhead, and is transferred to the next section of the excavation column, i.e. to the next well in the course of mining lava.

Claims (1)

Invention Formula The method of controlling hard-to-collapse roofs in the development of reservoir fields, including drilling during well drilling into the roof of the reservoir, injecting fluid into the well in the mode of moistening roof rocks, placing in the well WB charges and blasting them and injecting fluid in the Well in the fracture mode due to the fact that, in order to create a controlled process of changing the strength and structural properties of the roof rocks and improving the efficiency of fracturing, the drilling of wells lead beyond the reference pressure zone tim, further fluid is pumped into them elevated | viscosity and blasting charges WB pro- recension t after further injection of said liquid, then continues to inject liquid increased in viscosity to pressure fracturing  one T five with the subsequent maintenance of the proppant of the fluid and after re-reaching the pressure of the hydraulic fracturing and simultaneously reducing the flow rate of said fluid, a surfactant is injected into the well, which ceases to flow into the well when pressure decreases and the flow rate increases, then viscosity to fracture pressure is repeated until a steady pressure drop in the well is established, after which the process of weakening of the hard-to-break roof is transferred to the next one trabotki well. FIG. 2 eleven . . -I O..y.: - ..-. -L ... .. „-. -x  ... .     . L "..- .. S V ... / -. . . ./. ".about .. . "I    . . .    - . . . -I      . -. | | | .. ..: : .-. : - then ::;: n  . L “. S v / -. ./. ..   I . . .   - I) one S € ъ