RU2465461C2 - Open development method of mineral resources deposits - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: first, regular hexagons with the sides equal to diameter of the main wells are marked on plane of extraction field. Then, external and central circles with diameter equal to diameter of extraction wells are marked at tops and in the centre respectively of the above hexagons. Besides, each boundary circle of one hexagon adjoins three circles of two neighbouring hexagons as per close packing scheme. After that, core of central well is drilled in the centre of hexagon by means of core method with pre-drilling of service well. System of cracks directed perpendicular to axis of wells is made out of the cavity of the above well at the depth of core drilling of external wells, or slot raise with diameter equal at least to 2.4 of the extraction well diameter is cut. After that, cores of the rest six extraction wells with the centre at tops of hexagons are drilled and lifted. Therefore, core drilling cycle of six of seven wells excludes technologically complex and time-consuming operation of core removal from rock mass.

EFFECT: improvement of drilling capacity of core of large diameter due to their preliminary cutting prior to the beginning of the well drilling.

3 cl, 6 dwg

Description

The invention relates to mining and can be used in the open development of mineral deposits, mainly tube-shaped low-volume diamondiferous kimberlites, or in the refinement of the root of diamond deposits after excavation by underground mining, as well as in drilling stone columns for buildings and shafts for paper machines or tunneling mine shafts .

A known method for the extraction of stone raw materials by drilling a core of large diameter in the form of cylindrical shells with a coaxial core set [1]. In this method, due to the formation of a large-sized cavity in the center of the core to separate the core from the array, it is possible to place in the core separation zone a device with a cutting tool or a high-pressure feed device for abrasive air mixtures, which upon rotation form a cutting gap in the core, as well as other large and small-sized devices. Such spatial diversity of rock-destroying drilling elements and core separation devices, in turn, allows to reduce the width of the end face of the drill bit, therefore, power and other energy parameters of rock destruction. However, the significance of all this is reduced by the need to drill in the center of each core core of a significant diameter and a narrow scope of this method.

There is a method of developing mineral deposits by core drilling, which can be carried out by various devices for drilling the core method of large diameter wells (hereinafter - diameter D), for example, a mechanical core drill [2].

In this method, first, an auxiliary well of small diameter is passed in the usual way, then a device for core removal is introduced into this well, and at the same time, a large diameter well is passed with a core drill. Core separation is carried out by wedges directed perpendicular to the axis of the core and clogged by the impact of the drill pipe string.

The main advantage of this method is that diamonds remain intact in the volume of large diameter kimberlite core. In addition, since the core is detached only from the impact in the auxiliary well, it becomes possible to drill a large-diameter well with a crown with a minimum width of its end part, which reduces the load on the core tube and crown.

The main disadvantage of this method of mining is the need to drill in the center of each excavation well a special auxiliary well with the installation of a device for separating core from the array. The disadvantages should also include the impossibility of using workable and simple in design, but often large-sized core trimming devices. In addition, when drilling core of strong elastoplastic rocks that are difficult to break by impact, a core breaking device is additionally placed along the outer diameter of the well, which sharply increases the width of the bottom of the well and reduces the drilling speed.

Thus, to address these shortcomings and achieve a technical result to increase the productivity of drilling core samples of different ores, the following tasks can be set:

- exclusion from the cycle of drilling a core of large diameter the operation of its separation from the rock mass;

- preliminary formation around one of the extraction wells perpendicular to its axis a circular cutting slot (hereinafter referred to as the cutting slot) or a similarly directed system of cracks (hereinafter referred to as the system of cracks) in the rock mass at a distance of the diameter of the drilled wells.

This problem can be solved as follows. According to the proposed method of developing minerals, including opening a mineral, drilling auxiliary wells of small diameter in the center of the core and extraction wells with drilling large diameter core, separating it from the array, lifting to the surface and removing from the core pipe, first, on the plane of the extraction field, the correct hexagons and circles centered on the vertices and in the middle of these hexagons, while the sides of the hexagons and the diameter of the circles are equal to the diameter of the extraction wells, and each outer circle of one hexagon adjoins three circles of two adjacent hexagons according to the “tight packing” scheme, then in the middle of the hexagons, core drilling of central excavation wells is carried out using a core method with preliminary drilling of the auxiliary well, from the cavity of which at the depth of drilling the core of the external extraction wells form a continuous system cracks directed perpendicular to the axis of the wells, or cut in the same directional cutting slits with a diameter equal to at least 2.4 diameters mochno wells then centered on the vertices of the hexagons carried core drilling-out the remaining six excavation wells located on the perimeter of hexagons.

When implementing the proposed method of production problematic is the disruption of the core of the excavation well in the middle of the hexagon. If you drill a well with a diameter of 1000 mm in kimberlite, then to break the core, you need to apply a force of 300-400 tons. To create such a separation force, it is necessary to apply a pressure of at least 150-200 atmospheres to the bottomhole device. Although in our time and 500 atmospheres is not a problem, however, the core itself can be destroyed by crushing under the core grabber, violating the conditions for transferring the separation force to the core. Therefore, the simultaneous action of destructive forces from inside and outside the core is necessary, which will make it possible to break off a kimberlite core with a diameter of more than 2 m.

Currently, there are many core separating devices, both separately installed in the cavity of the auxiliary well, and combined with the drill bit and core pipe. But for drilling a core of large diameter, the latter is impractical, since in this case the width of the end face of the crown increases, which requires significant axial loads and torque during drilling, which cause an unjustified increase in the weight of the drilling rig. In the presence of a cylindrical cavity in the center of the core, various types of energy can be transmitted through it to break it, which will be summed up with the separation force and the torsion moment transmitted by the core through the core holding device of the drilling rig. In this regard, it is possible to use various sawing devices, well expanders, heating devices, hydraulic fracturing, thermal stresses during heating, and even the energy of microexplosions. However, if there are cracks or fracturing zones intersecting the core in the section of the well, then large core samples are detonated in the most damaged part of the core, using core grabbing devices that overlap the core section.

New in the present invention is the guidance from the cavity of a previously drilled one of the extraction wells of a system of cracks or the eruption of a cutting gap in the rock mass around this well and the subsequent drilling of other excavation wells in contact with it and with each other. Due to this, the core failure operation is excluded for the last six wells, which greatly simplifies core lifting, and the width of the crown end will depend only on the strength of the core tube and crown body. The simplest solution for cutting a horizontal circular slit can be the use of core trimming devices with the corresponding reinstallation of their cutting organs, for example, according to Russian patents No. 232,526, 2,211,135, 819,301 and others. When pointing a system of cracks around one of the excavation wells with hydraulic fracturing in permafrost non-freezing liquids are used, having previously cut through the initial guide slots.

When drilling with cleaning the bottom of the water and from the point of view of maintaining the stability of the walls of the drilled wells, preventing curvature of the axis of the well and safe mining operations, you should lay the wells as soon as the last core is raised or the last slot is cut. At the same time, in the process of drilling a deep adjacent well, the bookmark column must be stable, which requires the use of a hardening bookmark, at least along its outer contour. Simple calculations show that the pillar volumes reach up to 9 percent of the total volume of extracted deposits, so the need for their drilling in each case is decided separately.

Based on the foregoing, we can conclude that the proposed method of mining mineral deposits in comparison with the prototype has the following advantages:

- decreases by 7 times the number of drillable auxiliary wells in the center of the core in the absence of additional devices that expand the width of the annular bottom hole of a large diameter well;

- 86% of wells are excluded from the core drilling cycle for the technologically complex and lengthy operation of separating the core from the array;

- the choice of devices for pointing a system of cracks or cutting a cutting gap in a rock mass around a central excavation well is little limited by their size;

- there is no need to drill an auxiliary well in the core method, since it is possible to obtain reliable information for determining the location (depth of drilling) and the method of separating the core of external wells from the array, selecting the type of crown and optimizing the parameters of the drilling mode with a large diameter core core.

From the analysis of known methods for the development of tube-shaped and other deposits, as well as drilling of stone cylindrical products, we can conclude that this proposal has novelty and significant differences from the known methods.

Figure 1 shows the implementation diagram of the proposed development method; figure 2 - core drilling of a central excavation well; figure 3 - cutting cracks in the array of deposits around the Central well; figure 4 is a section of figure 3 along aa; figure 5 is a tab of the Central excavation wells; figure 6 - core drilling of external excavation wells.

The method is as follows. After overburden deposits on the plane of the extraction field, regular hexagons 1 with sides equal to the diameter D of the extraction wells are marked, and on the tops and middle of the hexagons, the contacting circles 2 with a diameter equal to D (Fig. 1). In Fig. 1, a hexagon with circles is highlighted as an element of a continuous coating of a excavation field. Subsequent hexagons are arranged in such a way that the outer circle of one hexagon adjoins three circles of two adjacent hexagons according to the “tight packing” scheme. Then, in the middle of the hexagon, an auxiliary well 3 is drilled to the entire depth of the mineral, a core 4 is sequentially drilled from a central excavation well 5 of diameter D (Fig. 2).

Separation of the core of the central well is carried out from the cavity of the auxiliary well so that the external and central wells are drilled with crowns of the same type without devices for separating the core from the array. For this, a system of cracks is made between the raft and the reservoir with a hydraulic, mechanical or sandblasting device 6 or a circular slit 7 is cut through, cutting the pillars formed between the two outer circles of one hexagon and one circle of the other. Lifting up the device cut through the desired number of slots (Fig.3, 4).

Following this, to eliminate the curvature of external wells and collapse of the walls of the borehole in the fracture zone, as well as to ensure the safety of work, the central well is filled with a self-hardening tab 8 (Fig. 5). Moreover, the self-hardening tab is used mainly around the perimeter of the wells, and its central part is filled with waste rock 9. After that, cores 10 are drilled from the remaining six external excavation wells 11 centered on the vertices of the hexagons (Fig.6). At the same time, raising the core is not difficult, since all the core samples are cut in advance. But after trimming there remains an insignificant pillar 12 (core leg), limited by the contour 13 of the external extraction wells 11 and the contour of the cutting slots 7, it is necessary to tear the core by raising the core pipe with rotation. After lifting the last core from the well, its cavity is immediately filled around the perimeter with a self-hardening tab 8, and its central part is filled with waste rock 9.

Simple calculations carried out similarly to those described in [2] show that for partial trimming of the cross-hole pillars 14 with the legs at the protruding corners, the diameter of the circular slit 7 should be taken no more than 2.4D, and for the complete trimming of the pillar - no less than 2.6 D. In the latter In this case, the maximum diameter of the circular slit is limited by the need to save the legs 12 of the core of the extraction wells. The need to leave the legs is caused by the fact that not only the volume of destruction during cutting is reduced, but also core stability is ensured at the end of the drilling cycle.

If when lifting a core pipe with rotation, the core easily breaks away, which can be when drilling not very strong rocks, then a slit with a diameter of 2.4D is cut. In this case, the cross-hole pillars have an insignificant part in the corners of the uncut, which easily breaks when climbing. But at the same time, the cross section of the core leg increases, which can complicate its stall. Therefore, clarification of the diameter of the cutting gap is a matter of developing a specific mineral deposit.

Information sources

1. Egorov D.E. Advantages of drilling cylindrical stone products in quarries and methods of their separation from the rock mass [Text] / D.E. Egorov // Notes of the Mining Institute. T.167. Part 1. - 2006. - S.10-12.

2. A.S. 857431 USSR, class Е21В 25/00. Device for core separation [Text] / V.V. Chubarouv, V.V. Chunosov (USSR). - No. 2723301 / 22-03; declared 02/06/1979; publ. 08/23/1981, bull. No. 31. - 4 s .; silt.

Claims (3)

1. The method of open development of mineral deposits, including the opening of minerals, drilling auxiliary wells of small diameter in the center of the core and dredging wells with core drilling of large diameter, its separation from the array, lifting to the surface and extraction from the core pipe, characterized in that at first on the plane of the excavation field, regular hexagons and circles are drawn centered on the vertices and in the middle of these hexagons, while the sides of the hexagons and the diameter of the circles are equal to capacity wells, and each outer circle of one hexagon adjoins three circles of two adjacent hexagons according to the “tight packing” scheme, then in the middle of the hexagons with a core method with preliminary drilling of the auxiliary well, core cores of the central extraction wells are drilled from the cavity at the depth of drilling of the core of external excavated holes wells make a continuous system of cracks directed perpendicular to the axis of the wells, or directional cutting slits with a diameter not equal to m She 2,4 diameter recessed wells, then centered on the vertices of the hexagons carried core drilling-out the remaining six excavation wells located on the perimeter of hexagons. 2. The method according to claim 1, characterized in that the cavity of the drilled wells along their perimeter is filled with a hardening tab, and its central part is filled with waste rock. 3. The method according to claims 1 and 2, characterized in that the guidance of the system of cracks in permafrost around the central excavation well is carried out by hydraulic fracturing, using non-freezing fluids, after cutting through the initial guide slots.

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