RU2395679C1 - Method for development of hard-to-recover carbohydrates - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: method consists in arrangement of gas-dynamic rupture of bed by initiation of combustible mixture burning with release of high-temperature gaseous products and complex mechanical, thermal and physical-chemical impact at bed. Water combustible-oxidant mixture is used, which is prior to initiation of its burning is pumped into well. Its burning is initiated with the help of powder pressure generator, providing for additional formation of minor cracks net in bed, and their size is increased at the stage of water combustible-oxidant mixture burning. Burning temperature in zone of combustible-oxidant mixture burning is maintained as 1100-1600°K. Gas-dynamic rupture of bed is carried out, properties of which in process of dynamic loading provide for their irreversible deformation with residual cracks, which do not require fixation.

EFFECT: simplified technology of method implementation and reduction of costs for its realisation.

1 ex, 1 tbl

Description

The invention relates to the field of development of deposits of hard-to-recover hydrocarbons and can be used, in particular, for the decomposition of reservoir gas hydrates (clathrates) and to improve the reservoir properties of the borehole zone of a productive formation of a gas hydrate field.

Known methods for developing fields of hard-to-recover hydrocarbons using various methods of stimulating the formation, for example, using mechanical effects on the geological environment (RU No. 2007109548, 2007), generating a thermal field in the formation (RU No. 2231635, 2004), forming a heat flow by initiating in-situ combustion by supplying an oxidizing agent such as air, an oxygen-containing gas mixture (RU No. 2306410, 2007), use of radioactive hydrocarbons as a coolant (RU No. 2211319, 2003).

However, the implementation of these methods is associated with the need to use sophisticated technological equipment and, as a result, high costs, to ensure the safe transportation and injection of liquid radioactive waste, the tightness of the underground storage, as well as the creation of a radiation and environmental safety system.

A known method of developing deposits of hard-to-recover hydrocarbons, namely, a method of developing gas hydrate deposits (RU No. 2230899, 2004).

The specified method involves the operation of underground man-made cavities, in which an inclined or horizontal well is drilled taking into account the orientation of the fracture and with branches from the production well down, with the possibility of installing casing shoes in the underlying layer of the gas hydrate deposit, with the formation of a pile fastening with more than one piles to maintain an inclined or horizontal casing production site and the possibility of operating underground technological olostey with given their size and unchanged or specify the movement upwards of their position in the reservoir when applying coolant, and hydraulic fracture.

The disadvantages of this method are the complexity of the production technology, which is associated, in particular, with the need to drill an inclined or horizontal well, taking into account the orientation of the fracturing and with branches from the production wellbore, as well as with the need to maintain an inclined or horizontal production section of the casing string.

Closer to the invention is a method of developing fields of hard-to-recover hydrocarbons, which consists in conducting a gas-dynamic fracturing of a formation by first introducing a combustible mixture into the well and initiating its combustion with the release of high-temperature gaseous products and performing complex mechanical, thermal and physico-chemical effects on the formation (RU 2300629, 2007).

The gas-dynamic effect includes perforation at all intervals of the treated formation, assembly of an open-section sectional charge by passing a composite rod through the central channel with a developed surface of each section of the charge, tightening and pressing the sections of charge close to each other, and positioning the collected gas discharge diffuser of the outlet gas flow formed below when burning sections of charge, with through holes, setting the charge in the perforation interval, burning sections of charge, accompanied by an increase in temperature, the formation of hot powder gases and the creation of a pressure pulse. Simultaneously with the gas-dynamic effect on the formation, an additional chemical or thermal effect on this formation is carried out, for which several substances with the possibility of mixing are delivered to the perforation interval in the sealed compartments of the sealed container with an internal cavity, which is the central channel of the charge sections and the internal cavity of the diffuser, of the gas stream them between each other with hot powder gases and reacting when burning sections of charge, depressurization of the container and its compartments. At the same time, the reaction products enter the well fluid and the formation cracks with powder gases under the action of a pressure pulse.

The disadvantage of this method lies in the complex technology of the method and, as a consequence, in the significant cost of funds and time associated with the installation and operation of expensive equipment.

The objective of the invention is to simplify the technology of the method and reduce the cost of its implementation.

The problem is achieved by the described method of developing a field of hard-to-recover hydrocarbons, which consists in conducting gas-dynamic fracturing by initiating the combustion of a combustible mixture with the release of high-temperature gaseous products and the implementation of a complex mechanical, thermal and physico-chemical effect on the formation, in which, according to the invention, using aqueous fuel an oxidizing mixture, which is previously pumped into the well before initiating combustion, and they initiate its combustion with the help of a powder pressure generator, which additionally forms a network of small cracks in the formation, the size of which increases at the stage of combustion of the aqueous fuel-oxidative mixture, while the combustion temperature in the combustion zone of the aqueous fuel-oxidative mixture provides 1100-1600 ° C, and conduct gas-dynamic fracturing, the properties of which under dynamic loading provide the formation of residual cracks that do not require fixing.

The invention is illustrated by the example of the extraction of natural gas in the reservoir in a solid hydrated state. The method is as follows.

Using a punch open the bottom of the productive part. In the well after its perforation and pressure, a gas-dynamic fracturing is performed.

For this, an aqueous fuel-oxidation mixture is pumped into the well.

As an aqueous fuel-oxidation mixture (THC), you can use, for example, a mixture of ammonium nitrate 54% wt., Urea 14% wt. and water - up to 100% of the mass., antifreeze or oil, ammonium nitrate and water, etc.

After that, a powder generator is lowered into the well and, on command from the earth's surface, the combustion of an aqueous fuel-oxidation mixture is initiated.

At the same time, measures are taken to prevent dilution of THC with formation water or flushing liquids. To fulfill this requirement, if necessary, use rubber or foam rubber plugs, hydrophobic separation fluids or reduce the time spent by the THC in the well before burning it.

The amount of THC injected into the well is determined taking into account the geological and technological features of the well.

Combustion in a well completely or partially filled with liquid is accompanied by the formation of a large amount of gaseous combustion products in a closed object, which leads to an increase in pressure and temperature to values sufficient to break the reservoir rock. The pressure drop in the well occurs in the form of its pulsation with a damping amplitude over time, significantly exceeding the burning time of the powder charges and THC. As a result, the formation is subjected to complex mechanical, thermal and physico-chemical effects.

The mechanical effect is manifested in the formation of residual cracks in the near-wellbore massif. It is determined by the magnitude of the pressure created in the well, the nature of its change in time and duration of action.

Mechanical action is carried out in two stages. At the first stage, a pressure impulse is formed, characterized by a steep increase in pressure with a high amplitude and a short action time (fractions of a second). Thus, by means of a powder generator, not only THC is ignited, but also formation of a network of small cracks occurs in the formation. At the second stage, liquid THC is burned, this leads to the formation of a pressure pulse characterized by a long action time (several seconds) and a pressure amplitude sufficient to fracture the formation and increase the size of small cracks formed in the first stage.

Residual cracks formed in the formation do not require fixing, due to the properties of rocks, expressed in irreversible deformation during dynamic loading and unloading and the possibility of creating the necessary ratio between the borehole, reservoir and rock pressure in the well.

The dimensions of the resulting cracks and their orientation depend on the magnitude of the pressure created in the well, the rate of its growth in time and the duration of the pressure pulse. Estimates show that the length of the cracks formed using the described technology (GDF technology) reaches 25-30 m. The temperature in the combustion zone can reach 1100-1600K. During the combustion of PGD and THC, CO ₂ , CO, N ₂ , and HCl are formed.

Creating a system of cracks with powder pressure generators with subsequent processing of them with high-temperature reaction products formed during the initiation of combustion of an aqueous fuel-oxidative mixture due to the development of high pressure and temperature in a closed volume, provides an increase in the volume of cracks in the rock.

The above example illustrates the invention, but does not limit it.

The described method can also be used in the development of deposits of hard-to-recover hydrocarbons, such as high-viscosity oils, high-viscosity hydrocarbons of petroleum origin, such as bitumen.

Examples of a specific method are shown in the table.

The table shows the characteristics of the deposits and the results of field tests of the technology of the described method in borehole conditions.

As an aqueous fuel-oxidation mixture using a mixture of ammonium nitrate 54% wt., Urea 14% of the mass. and water - up to 100% of the mass.

The table uses the following conventions: Kp,% Rel. - porosity coefficient; CRC, MD - permeability coefficient; Qн, t / day - oil flow rate; Qв,% mass.- water flow rate; AB _1-2 , AB ₁ , BV ₆ , SE ₁ - water and oil reservoirs.

From the data of the table it also follows that this method allows to increase the productivity of wells within a given time of field development.

Thus, the method according to the invention allows the use of simpler technology, low-cost equipment and reagents for its implementation.

Claims (1)

A method of developing a field of hard-to-recover hydrocarbons, which consists in conducting gas-dynamic fracturing by initiating the combustion of a combustible mixture with the release of high-temperature gaseous products and performing complex mechanical, thermal and physico-chemical effects on the formation, characterized in that they use an aqueous combustible-oxidizing mixture, which is previously before initiating its combustion is pumped into the well, its combustion is initiated using a powder pressure generator I, which additionally provides for the formation of a network of small cracks in the formation, the size of which increases at the stage of combustion of the aqueous fuel-oxidation mixture, while the combustion temperature in the combustion zone of the fuel-oxidation mixture is 1100-1600 ° K, and gas-dynamic fracturing is carried out, the properties of which at dynamic loading ensure the formation of residual cracks that do not require fixing.