RU2543235C2 - Development method of shale deposits - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method consists in separation of the developed ore field into blocks isolated from each other in pillars. In the central part of each block along the bottom of the deposit there arranged are two horizontal wells as mine chambers, in which there installed with provision of an air gap is an explosive charge of alternating non-sealed containers loaded with an explosive and hollow ones dividing the charge into separate parts, which are all fixed at the well head on a rope. Containers are provided throughout the length of the charging composition with main detonating cables connected to each other at the well head, and with electric detonators with closed conductors. The working end of the containers filled with explosives is provided with a charge hollow. The second end is plugged. In order to reduce seismic action of explosion, the above containers are provided with detonators of short-delay blasting, which are mounted in a section of the detonating cable located in the inner cavity of the container. With that, an offset of one of the above detonators is connected to the main line of the detonating cable. An offset of the second detonator is connected to a backup line. Vertical production wells are arranged along the circuit of module units and provided with Khobot-Tornado vortex pumps with flow-airlift pipes providing operation of the pump. Development of the deposit is performed as per a three-stage modular circuit by series transition into neighbouring blocks isolated with pillars. At the first stage, mine formation fracturing is performed with further extraction of gas and gas condensate by means of production wells. At the second stage, heat treatment of fractured formations is performed by supplying under pressure of at least 2.0 MPa of high-temperature combustion products through vertical parts of horizontal wells into the bottom part of the formation with further removal of molten solid and viscous organic component parts. At the third stage, through vertical part of the horizontal wells there pumped to the cavity of the formation is an alkali solution to leach ash shale formations for extraction of rare-earth component parts.

EFFECT: improving development efficiency of shale deposits in areas with developed infrastructure of metropolitan cities due to improvement of environmental safety and economical effectiveness.

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Description

The invention relates to the field of gas, oil and leaching of trace elements from shale deposits, can be used to develop shale deposits as close as possible to developed megalopolis infrastructures.

Traditional methods of oil production are forced to leave up to 40-60% of technogenic reserves in separate reservoirs. Integrated economically viable technologies are needed to develop these residues, this mainly relates to shale deposits. The costs of drilling and equipping technological equipment cannot be recouped without comprehensive extraction of the entire volume of mineral resources and an increase in the service life of production wells.

To increase gas and oil recovery, methods are used to develop gas and shale deposits using nuclear explosive technologies, wells for the production of a nuclear explosion (V.I. Musinov Oil and gas production using nuclear explosions, Zh. Priroda, 1991, No. 11, p. 25-33). The essence of the method is the production in the reservoir of nuclear explosions of full internal action, not leading to the release of rocks to the surface. After blasting, production wells are drilled, one located in the cavity zone and two at a certain distance from it, and the field is being developed.

The use of underground nuclear explosions opens up new broad prospects for intensifying the development of oil and gas fields, increasing their gas and oil recovery many times over.

One of the reasons restraining the widespread use of nuclear explosions in the oil industry is the danger of radiation charging the atmosphere, the area of work, and the produced products (oil, gas, water). Some phenomena and processes that are fundamentally important for the industrial implementation of nuclear explosive technologies (NWT) have not yet been fully studied. These included a long-term (hundreds and thousands of years) forecast of the safety of explosion products left underground. Therefore, the zones of underground explosions are alienated forever, and even more so they cannot be used near megacities.

Closest to the proposed technical essence and the achieved effect is a method of developing shale deposits by the method of hydraulic fracturing (hydraulic fracturing). As a result of its use, there is an increase in the permeability of the bottomhole zone of low-permeable, weakly drained, heterogeneous and dissected reservoir layers. Hydraulic fracturing is the creation of artificial and expansion of existing cracks in the rocks of the bottomhole zone with high pressure, more than 60 MPa, of fluid. As a liquid, oil, fresh or mineralized water, oil products (fuel oil, kerosene, diesel fuel), etc. can be used. To prevent crack closure after lowering the pressure, either well-rolled coarse sand or artificial plastic or glass balls are introduced into the liquid. Pure quartz sand with a grain size of 0.5 to 1.0 mm was most widely used for these purposes. The entire system of fractures obtained, the radius of action of which can reach several tens of meters, connects the well with the productive parts of the formation remote from the bottom. The flow of fluids to the well comes from previously isolated highly productive zones, and the flow rates of wells sometimes increase several times.

The mechanism of fracturing during hydraulic fracturing is as follows: under the pressure generated by the pumping units in the well, the fracturing fluid is filtered primarily in the zone with the highest permeability. A vertical pressure difference is created between the layers, since the pressure in permeable layers is greater than in low-permeability layers. As a result, certain forces begin to act on the roof and sole of the permeable formation, higher and underlying rocks undergo deformation, and horizontal cracks form at the boundaries of the layers. It is necessary that the in-situ pressure is sufficient to ensure the flow of oil to the wells. In addition, in order to get good fracturing results, it is necessary to treat the wells with hydrochloric acid and hydrofluoric acids. After establishing pressure at the mouth of the injection wells, they are washed, cleaned of sand and chemical impurities, only after that they begin to develop them. (Methods of mechanical fracture of a formation or its bottomhole zone, htth: www.qubkin.ru/faculty/maqistr-traininq/maqistranru/posobi 03/16/2013).

As can be seen, the extremely high resource intensity and low recoverability of highly viscous shale resins put the extraction method under consideration among inefficient and environmentally hazardous water resources.

Drilled wells quickly reduce their flow rate by 30-40% per year, while leaving in the bowels the main organic components in the form of dissolved kerogens, viscous shale resins and mineral components from the array, subject to hydraulic fracturing of reservoirs.

In addition, significant volumes of waste contaminated water can accumulate near the developed fields, which is difficult to dispose of in compliance with environmental standards.

The present invention is aimed at improving environmental safety and economic efficiency in the development of shale deposits in areas with developed infrastructure of megacities.

The result is achieved by the fact that the method for developing shale deposits is that the explored ore field is divided into blocks isolated from each other by pillars, in the central part of each block, two horizontal wells are placed as mine chambers in the central part of the deposit field, in which they are installed with air the gap of the charging composition of alternating charged explosive and empty leaky, separating the charge into separate parts, containers fixed at the wellhead on a cable, ontainers supply the entire length of the charging composition with main detonating cords connected to each other at the wellhead and with detonators with closed conductors, the working end of containers filled with explosives is formed with a cumulative recess, the second end is plugged, to reduce the seismic effect of the explosion, these containers are equipped with detonators slow action mounted on a segment of a detonating cord located in the inner cavity of the container, while the tap about of one of these detonators is connected to the main trunk line of the detonating cord, the outlet of the second is connected to the backup line, production vertical wells are placed along the contour of the module blocks and equipped with Hobot-Tornado vortex pumps and, if necessary, fountain-airlite pipes that ensure the pump operates at temperatures up to ^600, field development produced by the three-stage modular circuit passing in succession adjacent blocks entirely isolated: 1 to produce a step gap mine mp ists followed by selection of the gas and condensate through production wells; at the second stage - heat treatment of fractured formations by supplying at least 2.0 MPa of high-temperature combustion products through the vertical parts of horizontal wells to the bottom of the formation with pressure, followed by extraction of the molten solid and viscous organic components; at 3 stages, an alkaline solution is pumped through the vertical part of the horizontal wells into the formation cavity in order to leach the ash shale formations to extract rare-earth components.

Hydrocarbons in shale deposits are in a gaseous, liquid and solid state in the pores of the reservoirs and make up 10-30% of the mass of the rock, in shales of very high quality can reach 50-70%. Combustible shale deposits characterize fine-grained sedimentary rocks containing minerals. Shales contain a significant amount of trace elements that plants have accumulated as a result of bioaccumulation, such as lithium, titanium (up to 5400 g / t), boron (up to 10 g / t), rubidium, tantalum (0.28 g / t), selenium (up to 100 g / t), molybdenum (up to 750 g / t), rhenium (0.8 g / t), silver (3.2 g / t), gold (0.2 g / t), vanadium (up to 680 g / t), thorium (up to 12 g / t), barium (570 g / t), mercury, chromium (up to 380 g / t), tungsten (300 g / t), arsenic (2000 g / t), uranium ( 85 g / t), manganese (up to 290 g / t), germanium (up to 6 g / t), zirconium (530 g / t), beryllium (10 g / t), scandium (5.6 g / t), copper (up to 20 g / t), nickel (up to 57 g / t), cobalt (up to 27 g / t), gallium (up to 4.2 g / t), strontium (up to 500 g / t) and friend e elements. In addition, shale deposits contain large amounts of kerogen, which in turn is valuable as a hydrocarbon feed.

All these reserves can be located in areas with developed infrastructure and production, which are not covered by the interests of monopolistic organizations that extract oil and gases in large areas and regions, since the process of producing shale oil gas is more complicated. For example, to produce bitumen oil, you need to pump a huge amount of water into the reservoirs, 9-10 barrels of water per 1 barrel of oil produced, while the hardened and viscous parts of the oil are not extracted.

The method of developing shale deposits is illustrated in the drawings, where Fig. 1 shows a general view of the module, Fig. 2 shows an explosive charging device in a horizontal well, and Fig. 3 shows a "Hobot-Tornado" vortex pump device with fountain-airlift pipes.

The explored ore field is divided into separate modules, composed of at least three blocks isolated from each other by pillars 1, providing a three-stage development of a shale deposit:

mine fracturing, gas and gas condensate;

heat treatment of fractured formations and extraction of molten solid and viscous organic components;

leaching of rare earth trace elements from the ash portion of burnt formations.

In shale deposits, on top of the main shale deposit 2 (above the deposit) there are cover rocks 3, then sediments 4. In the central part of each block, two horizontal wells 5 are placed at the bottom of the deposit reservoir, serving as mine chambers, in which an explosive air gap is established the charging composition, including alternating charged 6 and empty non-tight containers 7, mounted on the cable 8. Along the containers 6 along the entire length of the charging composition set the main detonating cords 9, 1 0, which connect at the wellhead 5, electric detonators 11 with closed conductors are connected to them to protect against stray currents. The working end of containers 6 filled with explosives is formed with a cumulative recess 12, the second end is plugged with a plug 13. In charged containers 6, each part of the charge is sequentially blown up by short-delayed devices through a detonating cord in the direction from the bottom to the wellhead 5, reducing the seismic effect of the explosion, for whereby these containers 6 are provided with two short-delay detonators 14, which are mounted on a segment of the detonating cord located in the inner cavity of the containers 6, wherein the tap of one of these detonators is connected to the main trunk line of the detonating cord 9, the tap of the second is connected to the backup line 10. Vertical wells 15 are placed along the block contour, equipped with Hobot-Tornado vortex pumps 16. Hobot-Tornado vortex pumps 16 consist of a cone-swirler 17, made in the form of a funnel-cone, in the lower part of which a tangential pipe 18 for supplying compressed air is installed, and in the upper part a prefabricated snail 19 is connected to the main pipelines for the extraction of extracted products. (The operation of the Hobot-Tornado vortex pumps is described in the article by I.K. Sadrtdinova, AM Musaev. Use of bladeless draft blowers in municipal and industrial facilities for moving high-temperature and aggressive gases / Izvestiya KGASU, No. 1 (13), 2010, 212- 218). To operate the pump in the gaseous, liquid medium oil and sludge leaching at temperatures up to 600 ^{° C} and for selecting and viscous molten resins vortex pump "trunk Tornado" fountain 16 is provided with an airlift-pipes 20, 21.

A method of developing a shale field is as follows.

At the first stage of the development of the field, shale formations are mined 2. The blast is extended due to the alternation of charged containers and empty containers, as well as the presence of short-delay detonators 14, the charge is carried out in parts, in a short-delayed manner, with air gaps, in order to reduce the seismic effect of the explosion and preservation of the pillars 1. The impact on the in-situ pressure after fracturing of the mine charges 6 is carried out through the vertical parts of the horizontal 5 and vertical with wells 15. All production wells 15 undergo perforation of the faces, the mouth is equipped with Hobot-Tornado vortex pumps 16 with fountain-airlift pipes 20, 21.

After fracturing, methane and gas condensate components do not migrate to the cover layers 3, because due to the effect of rarefaction at the bottom of wells 15, in-situ pressure changes the vector of motion of gaseous products along the cracks of formations 2, directing them to the faces of production wells 15. In the process of fracturing rocks of formation 2, a compression wave is involved, forming a series of radial cracks propagating uniformly in all directions, from the bottom of the formation 2, and the reflected tensile wave, causing spall damage in the roof of the formation 2. These phenomena control the change in the specific consumption of explosives.

In Hobot-Tornado vortex pumps 16, oil gases or compressed gas under a pressure of at least 2.0 MPa are used to create an upward vortex with a tangential supply to the conical swirl 17 of the specified pump through a tangential nozzle inside which a Venturi nozzle is installed. Vortex upward flow at the wellhead 15 creates a vacuum at the bottom, affecting the in-situ pressure by distributing it across the vertical production wells 15. The vortex flow from the cone-swirl 17 of the Khobot-Tornado vortex pump 16, together with the extracted products, enters the collection coil 19 and goes into trunk pipelines or metering plants.

In the initial period, the selection of the gas phase from the reservoirs is carried out through a fountain pipe 20 having a Christmas tree, which can be converted into an airlift pipe 21 during the selection of viscous and molten resins. The Hobot-Tornado vortex pump 16 can work with gas, gas condensate, liquid and molten resins at temperatures up to 600 ^о С.

The assembly and installation of the charging composition is carried out by lowering into the well 5 charged 6 and empty 7 leaky containers that make up the explosive charge. Each container at the wellhead 5 is wrapped with adhesive tape together with the main detonating cords 9 and 10 and the fixing cable 8.

After completion of the mine fracture of formation 2 and extraction of gases and gas condensates through production wells 15, they proceed to the second stage of field development: heat treatment of fractured formations and extraction of molten solid and viscous organic components - liquefied oils and shale resins. To do this, use the vertical parts of horizontal wells 5 through which high-temperature products of combustion are supplied under high pressure (at least 2.0 MPa) to the bottom of the fractured, most permeable formations 2. An increase in the temperature of formations 2 leads to the thinning of hardened and viscous shale resins, which extracted by production wells 15 without changing their equipment, i.e. using vortex pumps "trunk-tornado" 16 using the central pipe as an airlift.

With the complete exhaustion of liquefied shale resins, the burning out of organic residues and the formation of the ash part of the reservoirs, they proceed to the next third stage of the development of the shale field - leaching of the ash parts of the shale formations to extract rare earth trace elements. Leaching can be complex or selective, depending on the value of the extracted metals.

As the blocks are mined, they are used as chambers for returning used solutions and oil refining wastes to the bowels.

The method involves the integrated development of deposits cost-effective and environmentally friendly methods. The method of developing shale deposits is carried out according to a three-stage scheme, sequentially switching to adjacent blocks in isolated pillars, i.e. carry out simultaneously different stages of field development in different blocks, sequentially and independently from each other carry out stages of field development.

The proposed method for the development of shale deposits according to a three-stage modular scheme for the development of shale deposits that are as close as possible to developed megalopolis infrastructures makes it possible to create multidisciplinary processing enterprises of organic components and rare earth microelements on the basis of unlimited volumes of mineral resources, some of which are of particular value. With the comprehensive extraction of all useful components of shale deposits for the regions, they can become not only a fuel reserve, but also high-tech industries with hundreds of new jobs.

The economic and environmental efficiency of integrated processing of extracted raw materials will significantly exceed traditional oil and gas production, especially in those regions where commercial oil and gas have not yet been found.

Claims (1)

1. A method for the development of shale deposits, which consists in dividing the explored ore field into blocks isolated from each other by pillars, in the central part of each block, two horizontal wells are placed as mine chambers in the central part of the deposit, in which an explosive charge of alternating charged explosives is set to provide an air gap substance and empty, separating the charge into separate parts, leaky containers fixed at the wellhead on a cable, the containers are supplied throughout Other than the charging composition, with main detonating cords connected to each other at the wellhead and with detonators with closed conductors, the working end of containers filled with explosives is formed with a cumulative recess, the second end is plugged, to reduce the seismic effect of the explosion, these containers are equipped with short-delay detonators, mounted on a segment of a detonating cord located in the inner cavity of the container, with the removal of one of these detonators in connect to the main trunk line of the detonating cord, the drain of the second is connected to the backup line; vertical production wells are placed along the contour of the module blocks and equipped with Hobot-Tornado vortex pumps with fountain-airlift pipes that ensure pump operation, the field is developed according to a three-stage modular scheme, sequentially switching neighboring blocks into isolated pillars: at the first stage, a mine is fractured followed by sampling of gas and gas condensate through production wells; at the second stage - heat treatment of fractured formations by supplying at least 2.0 MPa of high-temperature combustion products through the vertical parts of horizontal wells to the bottom of the formation with pressure, followed by extraction of the molten solid and viscous organic components; in the third stage, an alkaline solution is pumped through the vertical part of the horizontal wells into the reservoir cavity in order to leach the ash shale formations to extract rare earth components.

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