SU1719657A1 - Method for producing seam treatment - Google Patents

Description

The invention relates to the mining industry and can be used to reduce the gas content and the outburst hazard of host rocks and coal seams with a capacity of over 2.5 meters.

The purpose of the invention is to increase the safety of mining operations by providing intensive pumping liquid and deeper degassing of the productive strata.

The sequence of technological operations for the implementation of the invention is as follows. From the day surface to the resistant rocks of the developed coal seam, drill a well, surround it

pipes, plugging up the annulus, lowering a hydraulic perforator into the design point and cutting gaps in the horizontal plane of the well at the level of contact between the rocks and the main soil of the developed coal seam. A main crack is formed in them by injecting a working agent, the sand mixture is fed into the cracks and the sand plug is corked in the well to the coal seam. After alluvium sand

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The plugs in the borehole before the rock caving dome perforate the well at the level of the latter, form a main crack in these rocks by injecting a working agent and fix it with water-sand mixture.

Then a perforator is lowered into the well and the sand plug is washed away.

Having lowered the pump-compressor pipes into the well to the lower perforation interval, install a packer above it, pump air into the central column of pipes, displace the gas-liquid mixture to the surface through the annular space of the well.

Reinstall the packer below the upper perforation interval of the well, pump air into the annular space, displacing the gas-liquid mixture to the surface through the central column of pipes.

Master the well. The formation of a system of trunk cracks at the contact of the rocks of the direct and main soil of the developed coal seam in the body of the last willow of the dome of rock caving is due to the formation of additional sets between them, including vertical cracks, which provides the most favorable conditions for the flow of fluid into the soil rocks the expense of both the air-breakage of the collapsing dome rocks and the gravitational forces of the fluid.

The complex of predetermined force elements contributes to intensive degassing in the whole productive stratum and increasing well flow rates, reducing the water saturation of the stratum, dividing the host rocks of the coal seam into blocks, reducing the stability of the main soil rocks, etc. In addition, part of the methane from the productive stratum is brought to the surface through a trunk crack in the collapse dome before and after working the well through mining.

Thus, the creation of a single system of trunk and vertical cracks in the productive stratum will ensure effective degassing of the latter and will increase the safety of coal mining.

Example. Suppose you need to effectively degassing the reservoir under development. Let it lie at a depth of 580 m, has a capacity of 8 m, an effective porosity of 5%, and is characterized by an increased gas content of 15 m3 / t. Mudstone is found in the top of the seam 4-6 m in thickness, sandstone above it, up to 30 m thick. The soil of the seam is represented by carbonaceous argillite, up to 0.5 m thick, below (vertical) aleurolite and sandstone, 13-15 m thick. properties: crush 3.2-14.5 (sandstone), 3.1-8.4 (aleurolite), 1.6-3.8 (mudstone, carbonaceous mudstone) and 1.6-3.4 (coal) MPa .

A borehole is drilled to a depth of 620 m, lined with steel pipes, for example, 0.146 m in diameter with a wall thickness of 8 mm, the well annulus is plugged with cement. Perforator installation

at a given depth of 595–600 m, they provide a thorough measurement of the length of the pipes during tripping and determining the depth of the descent by a winch. For a more accurate installation of the perforator against the desired interval, a reporter coupling is used in the tubing string. After the AP-6M is lowered into the well, the wellhead is tied down and the pumping units are connected to it, the system is pressed

pressure exceeding the working 1.5 times. Before crimping, a 50 mm diameter ball is dropped into the tubing from the upper valve to seal the system. After crimping, the backwash, i.e. by pumping fluid into the annular space, the upper ball is brought to the surface and removed. Then, the small — lower ball — is dropped into the tubing and, when it is seated on the saddle, the fluid is injected only through six nozzles with a diameter of 6 mm, placed in a horizontal plane. After that, perforations are carried out by pumping into the tubing of the sandy mixture. The concentration of sand in a fluid is usually

80-UOkg / m3.

With hydroperforated perforation (GPP), the creation of holes in the column, cement stone and channel in the rock is achieved by imparting a speed of several hundred meters per second to the sand-liquid jet,

The lower limit of the allowable differential

in nozzles, providing effective

destruction of the column, cement stone and

breed should not be less than 12-14 MPa

(for 6 mm nozzles). With the strength of rocks (OSJ 20-30 MPa), it is advisable to increase the lower limits to 18-20 MPa.

The time of effective impact on the barrier should not exceed 15-20 minutes.

In the case of hydro perforated perforation, the same equipment is used as in the case of fracturing.

The wellhead is equipped with standard 1AU-700 fittings, calculated

at a working pressure of 70 MPa. For pumping. water sand mixture used pumping units 4AN-700, developing a maximum pressure of 70 MPa, at lower pressures - cementing units.

Water sand is prepared in a sand mixing unit (2.PA, ZPA, etc.). which is a sand bunker with a capacity of 10 meters with a conical bottom.

The pumping of fluid by the 4AH-7QO pumping units into the soil rocks of the coal seam is carried out in the dissection mode, which is accompanied by the opening and expansion of natural cracks. In doing so, the cracks are connected in a single hydraulic system oriented towards the injection well .;

The bottom hole pressure varies within 0.12 N R 0.25 N, kgf / cm2, where H is the depth of the reservoir, m. The rate of pressure of the working fluid is 40-60 L / s. The injection volume is determined by the formula

Q пВ2тпеф 3.14-1502 -3-0, m3, where R is the reduced radius of influence of the injection well, m ;.

m - power to be processed, m;

Pef - effective porosity of rocks, fractions.

Sand the well in the well to a coal seam.

A hydraulic perforator is lowered on the tubing and a hole is cut in the well in the middle of the thickness of the reservoir under development (584 m interval). The main fracture in the coal seam body is formed by injecting fluid in the fracture mode, which is understood as the bottomhole pressure, which provides hydraulic fracturing (HF) either along the strata or along natural fractures.

The resistance of rocks to rupture is usually small and lies within ar - 1.5–3 MPa; for coal, p is 1.5 MPa; therefore, it does not significantly affect Fr.

The fracture is produced through the casing, which allows the required pressure to be created at the bottom of the well, since the pressure losses due to friction when the fluid is pumped through the casing are small compared to the losses during injection through the tubing.

Parameters of coal seam rupture: fluid injection rate over casing 60 - 90 l / s; wellhead pressure 25-35 MPa. The process of water injection into the reservoir is recorded by the SCC monitoring station and stops in case of a sharp increase in fluid flow (absorptive capacity of the well) at the same pressure or in the case of a sharp decrease in pressure at the wellhead at the same flow rate.

As a fracturing fluid, fluids that penetrate well into a natural fracture and have a high viscosity are used, otherwise it will dissipate in the reservoir volume without causing a wedging effect in the resulting fracture.

In injection wells, clean or thickened water is used as a fracturing fluid. Thickening agents include components having a starch basis, polyacrylamide, sulfate-alcoholic bourd (PRS), KMSP carboxymethylcellulose). When using a water-based fluid, its interaction with the formation bed is taken into account, since some clay components of the formation are sensitive to water and prone to swelling. In such cases, chemical reagents are added to water-based liquids to stabilize clays when wetted.

After the coal seam has been fractured, a sand-carrier fluid is pumped at pressures holding the cracks formed in the reservoir in an open state. Sand is introduced into the opened cracks to the extent possible to prevent the closure of cracks during the subsequent pressure release and the transfer of the well into operation.

Pure quartz sand with a grain size of 0.5 to 1.2 mm is used for hydraulic fracturing; Modern technology allows the injection of 180-350 kg of sand (density of 2650 kg / m3) per 1 m3 of liquid. The amount of sand injected with a typical single fracture is 2-6 tonnes.

On the tubing into the well in the interval 555-560 m lower the sandblasting machine and cut the perforations with 6 mm nozzles. A trunk crack in the dome of the collapse of rocks is formed by the injection of fluid in the mode of rupture, similarly to the above.

Actual observations in lavas (Kizelovsky and Karaganda basins), while drilling wells (Kuznetsky, Chel Binsky and Kizelovsky basins) and development of contiguous formations show that the heights of the zones of collapse are insignificant compared to the height of the subsurface thickness and in most cases do not exceed normal to the bedding 3-4 times the reservoir capacity removed.

Let the height of the rock breakdown zone in the embodiment of the method be on average 25 m.

The fracture parameters of the collapse dome rocks (elevation 555–560 m): the rate of pumping fluid over the casing is 60–90 l / s, the pressure at the wellhead is 25–35 MPa. The process of pumping the working fluid into the well is recorded by the SCC control station, the injection stops in the event of a sharp decrease in pressure at the wellhead at the same flow rate.

2-6 tons of pure quartz sand with a grain size from 1.5 to 1.2 mm are pumped into fracture cracks (with an average consumption of 200 kg per 1 m of liquid). Water is used as a squeeze fluid.

A perforator is lowered into the well, the sand plug is washed out and the well is washed by known methods. The tubing is lowered into the well to the lower perforation interval and a packer is installed above it. At the first stage of well development, air is pumped into the central column of pipes by a compressor. The shutdown of the compressor is associated with the termination of the removal of the gas-liquid mixture from the annular space of the well to the surface. The number of cycles is determined by the volumes of pumped liquid in place.

At the second stage of well completion, the packer is reinstalled below the upper perforation interval (elevation 560 m), air is cyclically injected into the annular space of the well, trunk and vertical cracks of the collapse dome, the gas-liquid mixture is brought to the surface from the main cracks developed coal seam and rocks of its soil through the central column of pipes. The shutdown of the compressor is associated with the termination of the bleeding of the HS. The number of cycles is determined by the volume of fluid remaining after the first stage of development of the well.

The main advantages of the invention are as follows: effective reduction of the gas content of the productive stratum and gas abil

the stability of the developed lava space due to the unified system of main cracks formed in the coal seam and host rocks being developed by forcing a working agent; reduction of degassing periods of the productive stratum due to Zhetion, a working agent transported at high speed with a suction medium when using a central and annular schemes for lifting the gas-liquid mixture and gas.

Claims (1)

The invention of the method of processing the productive stratum, including drilling a well from the surface, casing the well, plugging of the annulus, the formation of cracks at the level of soil rocks and the dome collapsing of the developed coal seam by forcing the working agent, pumping out liquid and gas from the surrounding rocks and removing gas from the dome collapse rocks after underworking the sewage treatment works, so that in order to increase the safety of mining operations by ensuring intensive pumping liquid and deeper degassing of the productive stratum, the cracks are formed at the level of contact of the rocks of the main and immediate soil of the developed coal seam and at the middle of its thickness, then the tuber string is lowered into the well to the lower perforation interval of the casing, the compressed gas is fed into the central column of pipes and the gas-liquid mixture and gas are displaced from the productive layer through the annular space, after which the packer is removed and its lower position is set the upper interval casing perforations, wherein the compressed gas is fed into the annulus and displace the productive strata of gas-liquid mixture and the gas through the central pipe string to the surface.