UA137639U - METHOD OF GAS EXTRACTION FROM GAS HYDRATES - Google Patents

Abstract

A method of extracting gas from deposits of gas hydrates, comprising: opening a gas hydrate formation with a horizontal well; disintegration of the rock of the gas hydrate formation, starting from the bottom of the well, flooded with high-pressure water jets with an admixture of abrasive material (and to increase the volume of production hydromonitor nozzles are mixed on rods, which in the working position , together with the drill string gradually move to the front of rock disintegration); gravitational separation of the formed hydraulic mixture at some distance from the fracture front where the energy of the flows is extinguished and its mixing is slowed down; selection from production and subsequent separation in the separator located on the seabed, the target product, according to the utility model, the target product of the technology is gas obtained by melting gas hydrate in the process of disintegration of hydrate-containing rock due to thermal energy introduced into production with jets high-pressure water, which is heated in a heater located on the seabed, as a result of burning part of the extracted gas, and to maintain the combustion of gas in the heater air is supplied by a compressor from a surface intake through the air supply pipe, and combustion products are pumped from the heater recuperative heat exchanger for heating the extracted gas in order to prevent clogging of the line of its selection as a result of repeated hydration.

Description

The useful model belongs to the gas production industry, namely the extraction of gas from marine gas hydrate deposits. The main methods offered for gas extraction from gas hydrate deposits are: 1) pressure reduction below equilibrium hydrate formation; 2) heating of hydrate-bearing rocks to a temperature higher than the equilibrium hydrate formation;

C) introduction into the productive layer of substances that shift the equilibrium conditions of hydrate formation towards more rigid ones (inhibitors of this process).

Methods of extracting gas hydrates by mechanical grinding are also known.

Most of the proposed methods of developing gas hydrate deposits involve a combination of the methods listed above.

Today, a number of thermal methods of developing gas hydrate deposits are known. Thus, in patent 5 6192691, it is proposed to pump hot water under the dome for gas collection, installed above the bottom accumulation of gas hydrate. In the application O5 20050161217, it is proposed to carry out electric heating of the productive layer and extract the gas released from the production well.

An example of a method of reducing reservoir pressure (by pumping gas from lower horizons) is described in international application UUO 2007/072172.

However, rocks with a hydrate content greater than 60 95 are virtually impermeable to gas (1). Therefore, this method is acceptable for formations where hydrate saturation is insignificant, and gas or water has not lost its mobility.

Another disadvantage of methods based on pressure reduction is associated with secondary hydrate formation in the undercut zone as a result of the Joule-Thomson effect. For example, at a reservoir temperature of 283 K and a pressure of 5.7 MPa, the Joule-Thomson coefficient is 3-4 K per 1

MPa depression. Thus, with a depression of 3-4 MPa, the slaughter temperature can reach the freezing temperature of water. As a result, the gas hydrate will be preserved by a layer of ice for a long time (which will depend on the rate of heat input and will be determined by the thermophysical properties of the rock of the productive and adjacent layers).

In addition, gas hydrates perform the function of "cement" for the formation rock particles. their dissociation leads to abnormally high porosity and release of large masses of water |21.

Therefore, the dissociation of gas hydrate due to a decrease in pressure, an increase in temperature, or the introduction of inhibitors can lead to a decrease in the strength of sedimentary structures, the loosening of hydrate-cemented rocks and its transformation into an overmoistened unstable mass. As a result, an unlimited amount of rock along with water and gas will enter the wellbore, making its further exploitation possible. Therefore, methods based on traditional approaches - dissociation of gas hydrates and extraction of gas released through a well of classical design - will be ineffective.

The methods given in the applications 5 2008/0088171, UUO 00/47832 and VO 2004106857/03 provide for quarry development of marine gas hydrate deposits by their mechanical destruction. They are united by the fact that the object of the proposed methods is the accumulation of gas hydrates located directly on the seabed. However, most of the known hydrate occurrences are characterized by a relatively small hydrate content (gas hydrate fills the pores or is the cement of the mineral part of the reservoir). Therefore, the effectiveness of such methods will be questionable.

As the closest analogue, the one given in the patent OA 109336 |Z) was chosen. It takes into account the above features of gas extraction from gas hydrate deposits. This method involves: - opening of the gas hydrate layer with a horizontal well; - disintegration of the rock of the productive layer and its conversion into a hydraulic mixture, starting from the drilling of the well by means of mechanical grinding as a result of the action of submerged high-pressure jets of a mixture of water and abrasive material. To increase the volume of production, hydromonitoring nozzles are placed on rods, which in the working position are elongated, occupy a position perpendicular to the axis of the well and, rotating around it, together with the drill string gradually move to the rock disintegration front; - enrichment of the water mixture into gas hydrate as a result of gravitational sedimentation of part of the rock (at some distance from the destruction front, where the energy of the jets fades); - extraction from production and feeding (under pressure higher than equilibrium hydrate formation) to a separator located on the bottom of the sea, a water mixture previously enriched in gas hydrate for its separation into streams: gas hydrate, water mixture depleted in gas hydrate and rock; - pumping of the rock selected in the separator to the bottom of the sea or into the spent product; - supply of separated gas hydrate through the pipeline to the mining platform;

- selection of a part of the water mixture depleted of gas hydrate, addition of sea water to it and supply under pressure to the hydromonitoring device as a working mixture for rock destruction; - feeding the other part of the gas-hydrate-depleted water mixture into the sea under the gas-collecting dome through a pipe, the open end of which is located at some level above the upper limit of gas-hydrate stability, where due to its stay in non-equilibrium conditions and heat exchange with seawater, the remaining gas-hydrate dissociates into gas and water; - capture of the gas released as a result of the dissociation of the remaining gas hydrate under the gas collecting dome and its supply to the mining platform.

Therefore, the method proposed in patent SHA 109336 provides for extraction as the target product of the technology, mainly gas hydrate. However, this is precisely its drawback, since currently the gas production complex does not have implemented technologies for handling gas hydrates as energy raw materials (their transportation, storage, regasification). Therefore, the method of developing gas hydrate deposits will have competitive advantages, which will involve obtaining hydrocarbon gas technology as the target product.

The basis of a useful model is the task of developing a method of extracting gas from gas hydrate deposits that is industrially acceptable for the current state of the art.

To achieve the set task in the method of gas extraction from gas hydrate deposits, which includes: - opening of the gas hydrate layer with a horizontal well; - disintegration of the rock of the gas-hydrate layer and its conversion to the composition of the hydraulic mixture, starting from the wellbore, flooded by high-pressure water jets with an admixture of abrasive material (and in order to increase the production volume, the hydromonitoring nozzles are placed on the rods, which in the working position are elongated and occupy a perpendicular to the axis of the well position and, rotating around it, together with the drill string gradually move to the rock disintegration front); - gravitational separation of the formed water mixture at some distance from the destruction front (where its mixing ceases); - selection from production and subsequent separation in a separator located at the bottom of the sea of the target product, according to the useful model, the target product of the method is gas, which is obtained in

As a result of gas hydrate dissociation in the process of disintegration of hydrate-containing rock due to the energy introduced into the production with high-pressure water jets. The result of the gravitational separation of the formed aqueous mixture is the accumulation of gas in vaults, from where it is removed together with the aqueous mixture depleted in the solid phase. At the same time, the selection is carried out as a result of the manifestation of the airlift effect due to the excess pressure created in the production as a result of the inflow of the working fluid through the hydromonitors and the dissociation of gas hydrate into gas and water. In addition, the function of abrasive material in hydromonitoring submerged jets is performed by rock fragments that fall into them as a result of capturing part of the hydromixture. High-pressure water is heated in a heater placed on the seabed by burning part of the gas. At the same time, to maintain the combustion process, air is supplied through a pipeline from the surface of the sea. Combustion products are pumped into the sea by the compressor, but before that, the produced gas flow is heated in a recuperative heat exchanger to prevent hydrate formation.

The essence of the useful model is explained by the drawings, where in Fig. a schematic diagram of the method of gas extraction from gas hydrate deposits is given, where: 1 - mining in a gas hydrate layer; 2 - rock sediment; C - gas cap; 4 - intake device; 5 - aqueous mixture, depleted to the solid phase; 6 - hydromonitoring system; 7 - horizontal section of the well; 8 - three-phase separator for separating the aqueous mixture; 9 - water purification separator; 10 - heater; 11 - compressor; 12 - recuperative heat exchanger; streams: I - gas and a water mixture depleted in the solid phase; II - breed;

And - water; IM - gas selection line; M - combustion products removal line; MI - air supply line.

The method is carried out as follows.

The gas hydrate layer is opened with a horizontal well 7. Then, starting from the wellbore, with the help of the hydromonitoring system 6, the rock of the gas hydrate layer is destroyed for conversion into a hydraulic mixture. In the initial position, the hydromonitoring system 6 is in the well drilling mode - the rods with nozzles are pressed against the column (not shown in the diagram). The process begins with the fact that a working fluid under pressure is supplied to the hydromonitoring system b, the rods with hydromonitors begin to rotate around the axis of the well, high-pressure jets destroy the rock adjacent to the column, the formed hydraulic mixture is withdrawn through the intake device 4 and enters the three-phase separator 8.

Production 1 at the bottom of the well gradually expands, and the hydromonitoring rods gradually deviate 60 from the axis of the well until they take a position perpendicular to it. Further, disintegration of the rock occurs in the production of the maximum diameter. For this, the movement of the entire mining system along the axis of the well is added to the rotational movement of the hydromonitors on the rods.

The system is slowly removed from the well, maintaining a minimum distance between the sections of the nozzles of the hydromonitors and the front of the rock destruction. Before being fed to the hydromonitors, the working water (PI flow) is heated due to the energy of part of the produced gas in the heater 10. It is located on the seabed. To maintain the combustion process along the MI line, air is supplied to the heater 10 from the surface of the sea.

Combustion products (stream M) are pumped from it into seawater through the recuperative heat exchanger 12 to heat the extracted gas (stream IM). in order to prevent clogging of its selection line (IM flow) as a result of repeated hydrate formation. Circulation of air and gas combustion products is carried out using the compressor 11. In this case, the compressor 11 is located on the line between the recuperative heat exchanger 12 and the heater 10. Along the suction line, the compressor 11 creates a vacuum in the combustion chamber of the heater 10, providing air from the sea surface along the air supply line E. Along the injection line, the compressor 11 discharges the combustion products into the sea through the recuperative heat exchanger 12.

The initial stage of penetration of the production 1 is characterized by the fact that most of the rock is removed from it to the three-phase separator 8 together with the gas. This is due to the fact that in this area the entire hydromix in the production is exposed to the action of high-pressure jets, which leads to its active mixing. This makes it impossible to separate the solid phase of the rock from it by gravity.

However, upon reaching a certain length of the production, when the forces of gravity will exceed the action of the damping flows of the aqueous mixture, the gravitational separation of most of the solid phase will begin, as well as the accumulation in the vaulted part of the gas cap. After that, there is an established mode of product selection (stream I - gas and a water mixture depleted in the solid phase).

Gas and solid phase-depleted aqueous mixture (flow I) is taken by the intake device 4, which in the working position rises to the vault of the product 1. At the same time, part of the intake holes along its length is at the level of the gas cap 3, and part is immersed in the solid-depleted the phase of the aqueous mixture 5. The gas released as a result of the dissociation of the gas hydrate creates

The production pressure exceeds the initial formation pressure. The water supply pressure to hydromonitors is even higher. At the same time, the operation of hydromonitors is characterized by a certain level of water consumption.

Along with other factors, the effectiveness of hydraulic fracturing depends on the level of excess pressure in the nozzles of the hydromonitor over the reservoir pressure. Based on this, this system is regulated by the intensity of production selection from the well (throughput). At the same time, adjusting the selection pressure also regulates the ratio between the gas phase and the aqueous mixture.

Since both gas and water mixture enter the intake device, their further compatible transport is carried out in the gas lift mode.

The gas and solid phase-depleted water mixture (flow Y) enters the three-phase separator and is separated into the solid phase (flow II), gas (flow IM) and water with an admixture of the clay fraction of the rock (flow IP). Next, the solid phase (flow II) is removed to the seabed or into the spent production, gas (flow IM) is fed to the mining platform, and water with an admixture of the clay fraction of the rock (flow I) enters the water purification separator 9 to separate the maximum amount of the solid phase ( stream II). The prepared water is heated to the required level in the heater 10 and supplied to the hydromonitors.

Thus, the proposed method makes it possible to extract gas from gas hydrate deposits without complications associated with rock removal or self-preservation of the productive layer. In addition, this method corresponds to the existing level of development of technology in the gas production industry.

Sources of information: 1. Capable of developing gas hydrate deposits/ K.S. Basniev. V.V. Kulchytskyi, A.V.

Shchebetov, A.V. Nyfantov// Gas industry. - M.: - 2006. - Mo. 7. - P. 22-24. 2. KmepmoiYidep K.A. Sav Nuagaiez-deiodisa! regeresiimez apa dioba! snapde// NoUu. Seorpuvisv. - 1993. - Mine. 31. - R. 173-187. 3. Patent of Ukraine for the invention No. 109336. Method of development of marine gas hydrate deposits/

Pedchenko L.O., Pedchenko N.M., Pedchenko M.M.; applicant and patent owner M.M. Pedchenko - Mo a2014 00539; published 10. 08. 2015; Bul. May 15, 2015 - 7 p.

Claims (3)

USEFUL MODEL FORMULA 1. The method of extracting gas from gas hydrate deposits, which includes: opening of the gas hydrate layer with a horizontal well; disintegration of the rock of the gas-hydrate layer, starting from the wellbore, with flooded jets of high-pressure water with an admixture of abrasive material (and in order to increase the production volume, the hydromonitoring nozzles are stirred on the rods, which in the working position are elongated and occupy a position perpendicular to the axis of the well and, rotating around it , together with the drill string gradually move to the rock disintegration front); gravitational separation of the formed water mixture at some distance from the destruction front, where the energy of the flows fades and its mixing slows down; selection from production and subsequent separation in a separator located at the bottom of the sea of the target product, which differs in that the target product of the technology is gas, which is obtained as a result of the melting of gas hydrate in the process of disintegration of the hydrate-containing rock due to thermal energy introduced into the production with jets high-pressure water, which is heated in a heater located on the seabed, as a result of burning part of the produced gas, and to maintain the process of gas combustion in the heater, air is supplied by a compressor from an above-water intake through the air supply pipeline, and combustion products from the heater are pumped into seawater through recuperative heat exchanger for heating the produced gas in order to prevent clogging of the line of its selection as a result of repeated hydrate formation. 2. The method according to claim 1, which differs in that the function of the abrasive material in hydromonitor submerged jets is performed by rock fragments that are captured by these jets together with the hydraulic mixture in the area from the cut of the nozzle of the hydromonitors to the contact with the hydrate-bearing rock of the formation. 3. The method according to claim 1, which differs in that, as a result of gravity separation, the aqueous mixture is depleted into the main part of the solid phase, which settles to the bottom of the product, and gas, which accumulates in its vault, in addition, the release of gas, as a result of the melting of gas hydrate , and the entry of working high-pressure fluid into the production creates an excess pressure in it, which is used to extract gas and part of the water mixture depleted to the solid phase (to ensure water circulation) due to the gas lift effect.