US20200032631A1

US20200032631A1 - Method of enhanced oil recovery and intensification of production from oil, gas and condensate wells by means of hydromonitor radial underbalance formation penetration

Info

Publication number: US20200032631A1
Application number: US16/319,170
Authority: US
Inventors: Pavel Ivanovich POPOV
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-07-20
Filing date: 2017-07-20
Publication date: 2020-01-30
Also published as: RU2632836C1; EA034567B1; CN109477371A; EA201700331A3; EA201700331A2; WO2018016996A1

Abstract

The method includes installation in a well of a high strength tubing, a mechanical anchoring device, a turning device, a sealing device, a deflector, a circulation unit, a packer and a re-entry guide, a running hydromonitor nozzle, a wellbore trajectory control module, a navigation system, work and supply coil tubing sections, a flow re-distribution device, a check valve. By aerated fluid supply into an annulus between tubing and coil tubing and running coiled tubing, hydromonitor underbalance drilling of planned length of controlled radial channel in the formation is performed. Fluid with cuttings coming out the well through annulus between tubing and casing string, cleaned at surface and circulated back. After work coil tubing section retrieval from the formation and well underbalance circulation, the deflector is re-positioned to a different plane by mechanical turning device; the working cycle is repeated for the next radial channel. Milling of windows for all radial channels is performed before drilling stage, all subsequent works performed without well killing.

Description

FIELD

This invention is related to oil and gas industry, and namely to methods for circulation of oil, gas and condensate wells with use of liquids and gases including change of drainage area and coverage of wells due to creation of radial channels of filtration, and namely methods of enhanced oil recovery and intensification of production from oil, gas and condensate wells by means of hydromonitor radial underbalance balance formation penetration.

BACKGROUND

By the technique level there is a number of known drilling methods, for example, a method implemented with use of drilling device (patent RU 2118440C1, 27.08.1998), including drilling of the main wellbore and its reinforcement with casing string with pipe fitted with a guiding element, running of drill string with motor, bit and oriented drilling of the first radial channel, and in this process the guiding element deflects the tool. When required, in order to facilitate entry into one of deviated radial channels, a re-entry device can be run into the deflecting device, and after that drilling of the second radial channel is performed in similar way.
Deficiencies of the above-mentioned method include complexity of the device design, which leads to increase of financial costs for well construction, impossibility to include the main wellbore into operation, because the guiding element is not retrieved from the well, high radius of wellbore deviation, which results in the necessity of drilling an extended interval to the radial channel entry into producing formation, necessity to reinforce the radial channel with casing string and cement it.
The closest analogue of the declared invention is hydraulic drilling method (see US 2012/0186875 26.07.2012), which includes sealed installation of deflecting device with internal surface of work string on distal end of tubing work string, and the deflector is designed with an internal channel passing in it, and drilling string contains drill tubing section with internal bore, close end and distal end, and a device of through flow having at least one channel providing for fluid communication between annulus generated by internal surface of tubing work string and internal bore of drill tubing section when drilling tool is inserted into tubing work string, further the method includes connection of the drilling tool to the connecting string, entry of drilling tool into tubing work string, entry of at least part of drill tubing section into the deflector, supply of drilling mud under pressure into annulus generated between tubing work string and connecting string, and drilling fluid under pressure passes in through flow device into drill pipe and comes out at distal end of drill tubing section.
Deficiencies of the closest analogue include low efficiency of the method, caused by low coverage by radial channels in formation pay zone due to lack of navigation for drilling of channels and control over their trajectory, lack of opportunity to drill extended channel due to hazard of their uncontrolled passing beyond the formation boundaries and ingress into water-bearing intervals or their drilling in non-producing part of well profile.

SUMMARY

The invention objective is to remove the above-mentioned deficiencies by means of creation of a new method of enhanced oil recovery and intensification of production from oil, gas and condensate wells opening additional opportunities for recovery of hydrocarbons.
Technical deliverable of the declared invention is improvement of well productivity and oil recovery factor due to addition of drain area, coverage, removal of skin-factor and increase of formation matrix permeability, penetration of producing formation without intervention of process fluid into it with preservation of initial formation permeability, provided due to control of bottomhole pressure below reservoir pressure in the process of drilling of radial channels, an individual case of work in underbalance mode can be condition of equilibrium provided by equality bottomhole and reservoir pressures; provision of an opportunity of target treatment of the formation due to directed impact on the deposit with controlled radial channels, opportunity to perform intensification without impact on casing string cement by significant pressure differential or chemical destruction; opportunity to perform intensification by significant pressure differential or chemical destruction; cleaning of the wellbore in the process of its drilling—all of this allows to efficiently use the technology both in carbonate and in terrigenous formations.
The above-mentioned objective of the invention is resolved by means of creating a method of enhanced oil recovery and intensification of production from oil, gas and condensate wells with use of hydromonitor radial underbalance formation penetration, including: installation in the well of high strength tubing section, mechanical anchoring device, turning device, sealing device deflector with internal channel passing in it, its linking and potential spatial orientation in the lower level of radial channel drilling; successive installation of disconnector, circulation unit, packer and re-entry guide below the deflector; wellhead sealing, installation of downhole equipment of coiled tubing consisting of hydromonitor nozzle, wellbore trajectory control module, navigation system, work coil tubing section, flow re-distribution device, check valve, supply coil tubing section; supply of aerated fluid into annular between tubing section/coil tubing section or simultaneously into annular between tubing section/coil tubing section and internal space of coil tubing section or separate injection of fluid and gas into these two spaces; passing of hydromonitor nozzle through sealing device, through the deflector to contact the rock; underbalance drilling of planned length of radial channel is performed with use of navigation system for control over current position of wellbore in the formation and current bottomhole pressure, and also with use of wellbore trajectory control module in order to assure wellbore drilling along the designed trajectory; after drilling through the formation the work coil tubing section with the nozzle is retrieved from the formation and underbalance well circulation is performed until full carryover of cuttings, by means of activation of mechanical turning device the deflector is re-positioned to a different plane, the working cycle is repeated for the next radial channel; bottomhole pressure below reservoir pressure or equal to it is assured in the process of drilling in the formation, which is defined by fluid density reduced due to aeration and, when required, foam generation to needed values and controlled design ratio between gas and fluid supplied from surface with opportunity to change such ratio in compliance with actual bottomhole pressure measured in the radial channel; milling of windows in casing string for all radial channels is performed well in advance before switch to implementation of the main operation for drilling of radial channels by means of full-circle milling of casing string or sand-jet cutting of individual windows in casing string, in the process of radial channel drilling wellbore trajectory is determined and changed by means of provision of work coil tubing section with wellbore trajectory control module and navigation equipment. In individual case of execution of method for enhanced oil recovery and intensification of production from oil, gas and condensate wells by means of hydromonitor radial underbalance/equilibrium formation penetration for drilling of radial channels at next levels with previously prepared windows in casing string for drilling radial channels, supply coil tubing section and work coil tubing section are retrieved from tubing section, control over pressure in tubing section is performed by means of closing check-valve included into tubing assembly, unsetting the mechanical anchoring device with the high strength tubing, control over pressure in annulus between tubing and casing string is provided by wellhead sealing device, tubing landing joint installed in advance and equal to the length of transition to the next level is retrieved, tubing section is set on mechanical anchoring device, work coil tubing section with navigation system, wellbore trajectory control module, hydromonitor nozzle is run into the well, after that works associated with drilling of radial channels are repeated.
In individual case of execution of method for enhanced oil recovery and intensification of production from oil, gas and condensate wells by means of hydromonitor radial underbalance/equilibrium formation penetration at the stage of well preparation for works associated with cutting of windows in casing string, an additional sand-jet device on coil tubing section is run into the well, abrasive cutting of rectangular hole with circulation is performed, transition from one cutting spot to another is performed by means of mechanical activation of turning device to fixed discrete angle, cutting of all required rectangular holes for drilling of radial channels in casing string at one level is performed during one trip of sand-jet device on coil tubing section, then equipment for sand-jet cutting is pulled out and then drilling of radial channels is started.
In another individual option of execution of method for enhanced oil recovery and intensification of production from oil, gas and condensate wells by means of hydromonitor radial underbalance formation penetration, in the process of well preparation for works, full-circle milling of casing string is performed in intervals of planned drilling of radial channels.
In individual option of execution of method for enhanced oil recovery and intensification of production from oil, gas and condensate wells by means of hydromonitor radial underbalance formation penetration, final operations on the well after drilling of all radial channels are performed, which include retrieval of process equipment from the well and running of production assembly (for flow lift or pump) without well killing in the interval of drilled radial channels, by means of installation of isolating assembly above intervals of radial formation penetration installed before pulling of process equipment out of the hole after completion of works associated with drilling of radial channels, which prevents kill fluid contact with producing formation in intervals of radial penetration.

BRIEF DESCRIPTION OF THE DRAWINGS

Brief explanation of the invitation essence is presented in graphical materials.

In FIG. 1—Scheme 1 of declared method.

In FIG. 2—Scheme 2 of declared method.

In FIG. 1-2:

1—check-valve;
2—flow re-distribution device;
3—mechanical anchoring device;
4—turning device;
5—sealing device;
6—deflector;
7—navigation system;
8—wellbore trajectory control module;
9—hydromonitor nozzle;
10—sand-jet cutting device;
11—casing string;
12—high-strength tubing section;
13—supply coil tubing section;
14—work coil tubing section;
15—full-circle milled area (“window”) in the casing string;
16—passage hole (“window”) cut in casing string with sand-jet cutting device;
17—disconnector;
18—circulation unit;
19—packer;
20—re-entry guide.

Further options are provided below, which are not exhaustive.

DETAILED DESCRIPTION OF THE NON-LIMITING EMBODIMENTS

The following assembly on high strength tubing section is run into the well prepared for radial formation penetration with milled “windows” in casing string in spots of drilling of radial channels: re-entry guide, packer, circulation unit, disconnector, deflector, sealing device, turning device, mechanical anchoring device. The deflector is installed with linking, when required—with gyroscope orientation, in the interval of lower level of drilling of radial channels. Downhole equipment on 38 mm coil tubing (flexible tubing) is run into the well (into 89 mm tubing). This equipment includes: hydromonitor nozzle, wellbore trajectory control module, navigation system, 38 mm work coil tubing section of designed length equal to designed length of radial channels (up to 500 m and more), flow re-distribution device, check valve, 38 mm supply coil tubing section. Then wellhead sealing is performed, and after that fluid with inert gas (cryogenic nitrogen) for formation penetration is supplied into annulus between 38 mm supply coil tubing section and 89 mm tubing, by means of supply coil tubing section hydromonitor nozzle with work coil tubing section is passed through sealing device, comes out of the deflector to contact the rock/cement. Drilling of planned length of radial channel is performed with control of bottomhole pressure below reservoir pressure or equal to it (underbalance or in individual option underbalance—equilibrium) with use of navigation system for control of current wellbore position in the formation, and also with use of wellbore trajectory control module to assure channel drilling along the designed trajectory. In this process aerated fluid passing in small annulus between tubing section and coil tubing section, flow re-distribution device, then through work coil tubing section, through hydromonitor nozzle and gets into radial channel making a radial channel further, and along with products of rock destruction through the drilled radial channel returns into the well and comes to the surface in annulus between tubing and casing string. On the surface the fluid is degassed, cleaned of hydrocarbons and products of rock destruction, if required, it passes additional chemical treatment and returns through circulation into the well. The pump shuts off and by means of coil tubing section passing through turning device, with guaranteed accuracy, deflector turns due to activation of mechanical turning device. Operation associated with underbalance drilling of the next radial channel or in individual option—underbalance-equilibrium is repeated. After drilling of required number of radial channels at one level, full pulling of coil tubing out of the hole is performed. Tubing landing joint which previously was made up in the upper part of tubing string with length designed for transition to the next level is retrieved. The well is not killed, control of pressure in tubing section is performed by means locking of check-valve included in tubing assembly, and control of pressure in annulus between tubing and casing strings is provided by means of wellhead sealing device. Deflector is installed on tubing section in planned interval on mechanical anchoring device. The work cycle is repeated. Full pulling of coil tubing out of the hole is performed after drilling of designed number of radial channels. Operations are performed without well killing, control of pressure in tubing section is performed by means of locking of check-valve included into tubing assembly, and control of pressure in annulus between tubing and casing strings is provided by wellhead sealing device. The mechanical anchoring device is unset and lifted to the design length with the high strength 89 mm tubing with installation of re-entry guide above intervals of drilling of radial channels, packer is set and pressure-tested in annulus between tubing and casing strings. Tubing string with deflector is disconnected from the packer with circulation unit by means of activation of disconnector and killing of well space above the packer, and the packer and circulation unit isolate interval of radial formation penetration from contact with kill fluid, under packer zone is not killed. The well is killed, tubing string with deflector is fully pulled out of the hole. Further operations can be performed in 2 options, with use of different types of circulation units.
The first option is related to flowing method of well production. Production tubing fitted on the bottom with top response part of the disconnector connected to bottomhole assembly of re-entry guide/packer/circulation unit/bottom response part of disconnector is run into the well. X-mas tree is installed on the well, the well is hooked-up to flow line, required pressure-testing operations are performed before the well startup. Fishing tool for stop valve of circulation unit is run on coil tubing section with use of aeration to control bottomhole pressure at the level below reservoir pressure, then it is connected with stop valve and retrieved from the well. In this process bottomhole pressure during the entire cycle of operations associated with radial formation penetration is below reservoir pressure or is equal to it. The well is transferred to flowing mode.
Through the open internal passage in circulation unit, packer and re-entry guide it is possible to perform geophysical works in the interval of producing formation, with use of coil tubing section and nitrogen supply it is possible to circulate bottomhole and perform repeated installation of stop valve into circulation unit in order to kill the well and perform its workover without contact of process fluids with producing formation. If it is required to retrieve bottomhole assembly consisting of re-entry guide/packer/circulation unit/lower response part of disconnector, the well is killed, by means of tubing tension packer is put into transportation position, well circulation and full pulling of production tubing is performed.
Option 2 is related to well production with artificial lift.
Production tubing with the pump is run to design depth. X-mas tree is installed on the well, the well is connected to flow line, required pressure-testing operations are performed before well startup, then the well is started with its flow into the flow line. After decrease of fluid level to the set value, circulation unit provides for communication between under-packer space with above-packer space, and thus inflow of formation fluid from formation to the well is performed. For the purpose of well bottom circulation or implementation of geophysical operations in the interval of producing formation, tubing section with pump is retrieved from the well. Process tubing section fitted on the bottom with top response part of disconnector is run into the well, connected to bottomhole assembly consisting of re-entry guide/packer/circulation unit/bottom response part of disconnector. Then a fishing tool for stop valve of circulation unit is run into the well on coil tubing section with use of aeration for control of bottomhole pressure below reservoir pressure or equal to it, the fishing tool connects to the stop valve and retrieves it from the well. In this process bottomhole pressure is below reservoir pressure or is equal to it. Bottomhole circulation and/or geophysical operations in the interval of producing formation are performed through open internal passage in circulation unit, packer and re-entry guide with underbalance. After completion of these operations and with use of coil tubing section or cable equipment, repeated installation of stop valve is performed, then process tubing section is disconnected from bottomhole assembly, well killing is performed, process tubing section is pulled out of the hole and production tubing section with a pump is run into the hole, the well is started up for operation. If it is required to retrieve bottomhole assembly consisting of re-entry guide/packer/circulation unit/bottom response part of disconnector when process tubing section is run into the hole, the well is killed, and process tubing section is connected to bottomhole assembly, by tubing tension the packer is put into transportation position, the well is circulated and full pulling of process tubing section is performed.
Below is one more of potential examples with variation by two methods (see example and FIG. 1, FIG. 2 below) for realization of the invention, which in no way limits all possible options of its execution. For convenience the example is provided with references to graphical materials.
[1] An assembly consisting of re-entry guide (20), packer (19), circulation unit (18), disconnector (17), deflector (6) having passage channel with side outlet, sealing device (5), turning device (4), mechanical anchoring device (3) is run into the well killed and prepared for implementation of radial underbalance formation penetration (RFP) or in individual option with overbalance—equilibrium on high strength tubing (12).
The assembly can also include additional elements not limited by this list: linear stress compensator, the second disconnector installed above the deflector, check valves and other.
By geophysical method the deflector is linked with its side channel to the interval of full-circle milled casing string (15). Tubing assembly is set on mechanical anchoring device (3) taking the link into account so that the deflector outlet (6) is aligned with open (full-circle milled) part of the casing string (15).
[2] There is another method (see FIG. 2) to assure communication of side outlet of the deflector (6) with formation by means of using sand-jet cutting of rectangular “window” (16) in the casing string (11). In order to perform this task, the above-mentioned assembly is run into not milled casing string, then it is set on mechanical anchoring device (3) with link by geophysical method.
[3] Further, sand-jet cutting device (10) on coil tubing section (13) is run into the tubing (12), which comes to connection with the deflector and the end with the nozzle is directed to casing string wall (11). Fluid is injected into coil tubing section (13) to create fluid circulation which comes out of the well in annulus between casing string (11) and tubing (12). Abrasive material (quartz sand, proppant, etc.) is added into the fluid flow on the surface, which passes through the device nozzle (10) and destructs casing string wall making a passage hole (16). Creation of a rectangular passage hole (16) is provided by moving sand-jet device nozzle down (10). Cutting of all required rectangular holes for drilling of radial channels at one level is performed during one trip of sand-jet device on coil tubing section using fixed turn of the deflector due to activation of mechanical turning device with discrete turning angle.
[4] Assembly for radial formation penetration consisting of hydromonitor nozzle (9), wellbore trajectory control module (8), navigation system (7), work coil tubing section (14) is run into the well (FIG. 1) into tubing section (12) on supply coil tubing section (13) with flow re-distribution device (2) and check-valve (1). The assembly for radial formation penetration can also contain additional elements not limited with this list of downhole equipment.
[5] Supply of aerated fluid is performed into annulus between coil tubing section (13) and tubing section (12) in the process of coil tubing section (14) and (13) running into tubing section (12) in order to equalize pressure in the well. When depth of mechanical anchoring device (3) installation is achieved, increase of injection flow rate of fluid aerated with nitrogen to the design mode is performed, full circulation is achieved with fluid coming out in annulus between tubing (12) and casing string (11). Drilling of planned extension of radial channel is performed with underbalance or in individual option with underbalance-equilibrium with use of navigation system (7) in order to control current position of the radial channel in the formation, and also with use of wellbore trajectory control module (8) in order to assure radial channel drilling along the design trajectory and hydromonitor nozzle (9) in order to create a radial channel Fluid coming out of the well is directed back into the well through the degassing and treatment system.
[6] Coil tubing section (14) movement down is achieved by means of running coil tubing section (13), this provides for hydromonitor nozzle (9) coming out of the deflector (6) and casing string (11), then hydromonitor drilling of radial channel of design length is performed in the producing formation with underbalance or in individual option with underbalance-equilibrium.
[7] Determination of geographical coordinates of radial channel bottom in the formation and their reference to lithological profile is performed by means of navigation system (7) which transmits information to the surface by cable communication channel Wellbore trajectory control model (8) controlled from the surface by hydraulic or cable communication channel is used to drill a radial channel along the design trajectory, change its trajectory when approaching boundary of the selected formation interval.
[8] When final design point (bottom) of radial channel is achieved, hydromonitor nozzle (9) on coil tubing section (14) is retrieved from the formation with its installation below sealing device (5). Washing is performed with nitrogen aeration and underbalance or in individual option with underbalance—equilibrium to achieve full removal of cuttings from annulus between tubing (12) and casing string (11).
[9] After completion of circulation (the well is not killed and is under excessive wellhead pressure), coil tubing section (14) is run with passing through turning device (4) required number of times (each coil tubing section passing through turning device provides for deflector turn to a certain discrete angle) and thus deflector turn to the angle designed for drilling of the next radial channel is achieved.
[10] In cases when during well preparation for radial formation penetration full-circle milling of the casing string was performed or when during one trip of sand-jet device on coil tubing section cutting of all required rectangular holes for drilling of radial channels at one level was performed, operation [6] is started, and then operations [7], [8], [9] are successively performed.
[11] For transition to the next level of drilling of radial channels by well profile (the well is not killed and is under excessive wellhead pressure), after implementation of drilling of all planned radial channels at one level, the assembly on coil tubing section (13), (14) is pulled out of the hole. Control over pressure in tubing section is performed by means of locking of check-vale included into tubing assembly, and control over pressure in annulus between tubing and casing strings is provided by wellhead sealing device. Unsetting the mechanical anchoring device (3) with the high strength tubing (12), tubing landing joint of design length (previously installed), providing for deflector lift to the next level is retrieved from the well.
[12] Tubing assembly is set on mechanical anchoring device (3) so that deflector (6) outlet is aligned with open (milled) part of the casing string (15).
[13] For drilling of radial channels with underbalance or in individual option with underbalance-equilibrium at each level of well profile, operations [4], [5], [6], [7], [8], [9] are successively performed.
[14] For transition to each next level for drilling of next designed radial channels with underbalance or in individual option with underbalance-equilibrium, operations [11], [12] are performed.
[15] Operations [4], [5], [6], [7], [8], [9] are successively performed for drilling of radial channels with underbalance or in individual option with underbalance-equilibrium at each level of well profile.
[16] After drilling of planned number of radial channels at all levels of well profile and well circulation to remove cuttings, coil tubing section (13) and coil (14) is pulled out of the hole. All works are performed without well killing, control over pressure in tubing section (12) locking of check-valve included in tubing assembly (12), and control of pressure in annulus between tubing (12) and casing (11) strings is provided by means of wellhead sealing device, the mechanical anchoring device is unset and lifted to the design length with the high strength tubing string (12) with installation of re-entry guide (20) above intervals of drilling of radial channels, packer (19) is set and pressure-tested in annulus between tubing (12) and casing (11) strings. Tubing (12) string with deflector (6) is disconnected from the packer (19) with circulation unit (18) by means of activation of disconnector (17) and killing of well space above the packer, and the packer (19) and circulation unit (18) isolate interval of radial formation penetration from contact with kill fluid, under packer zone is not killed. The well is killed, tubing (12) string with deflector (6), sealing device (5), turning device) (4), mechanical anchoring device (3) is fully pulled out of the hole. Further operations can be performed in 2 options, with use of different types of circulation units (18).
The first option is related to flowing method of well production. Production tubing section fitted on the bottom with top response part of the disconnector (17) connected to bottomhole assembly of re-entry guide (20)/packer (19)/circulation unit (18)/bottom response part of disconnector (17) is run into the well. X-mas tree is installed on the well, the well is hooked-up to flow line, required pressure-testing operations are performed before the well startup. Fishing tool for stop valve of circulation unit (18) is run on coil tubing section with use of aeration to control bottomhole pressure at the level below reservoir pressure, then it is connected with stop valve and retrieved from the well.
In this process bottomhole pressure during the entire cycle of operations associated with radial formation penetration is below reservoir pressure or is equal to it. The well is transferred to flowing mode.
Through the open internal passage in circulation unit (18), packer (19) and re-entry guide (20) it is possible to perform geophysical works in the interval of producing formation, with use of coil tubing section and nitrogen supply it is possible to circulate bottomhole and perform repeated installation of stop valve into circulation unit (19) in order to kill the well and perform its workover without contact of process fluids with producing formation. If it is required to retrieve bottomhole assembly consisting of re-entry guide (20)/packer (19)/circulation unit (18)/lower response part of disconnector (17), the well is killed, by means of tubing tension packer (19) is put into transportation position, well circulation and full pulling of production tubing section is performed.
Option 2 is related to well production with artificial lift.
Production tubing section with the pump is run to design depth. X-mas tree is installed on the well, the well is connected to flow line, required pressure-testing operations are performed before well startup, then the well is started with its flow into the flow line. After decrease of fluid level to the set value, circulation unit (18) provides for communication between under-packer space with above-packer space, and thus inflow of formation fluid from formation to the well is performed.
For the purpose of well bottom circulation or implementation of geophysical operations in the interval of producing formation, tubing section with pump is retrieved from the well. Process tubing section fitted on the bottom with top response part of disconnector (17) is run into the well, connected to bottomhole assembly consisting of re-entry guide (20)/packer (19)/circulation unit (18)/bottom response part of disconnector (17). Then a fishing tool for stop valve of circulation unit (18) is run into the well on coil tubing section with use of aeration for control of bottomhole pressure below reservoir pressure or equal to it, the fishing tool connects to the stop valve and retrieves it from the well. In this process bottomhole pressure is below reservoir pressure or is equal to it. Bottomhole circulation and/or geophysical operations in the interval of producing formation are performed through open internal passage in circulation unit (18), packer (19) and re-entry guide (20). After completion of these operations and with use of coil tubing section or cable equipment, repeated installation of stop valve is performed in circulation unit (18), then process tubing section is disconnected from bottomhole assembly, process tubing section is pulled out of the hole and production tubing section with a pump is run into the hole, the well is started up for operation. If it is required to retrieve bottomhole assembly consisting of re-entry guide (20)/packer (19)/circulation unit (18)/bottom response part of disconnector (17) when process tubing section is run into the hole, the well is killed, and process tubing section is connected to bottomhole assembly, by tubing tension the packer (19) is put into transportation position, the well is circulated and full pulling of process tubing section is performed.
Thus, application of the declared method provides for:

- improvement of well productivity and oil recovery factor due to addition of drain area, coverage, removal of skin-factor and increase of formation matrix permeability;
- application of the technology under conditions of abnormally low reservoir pressure for development of deposits of hydrocarbons;
- improvement of efficiency of application of this radial formation penetration technology with underbalance or in individual option with underbalance-equilibrium compared to previous analogues and prototypes of technologies for enhanced oil recovery with underbalance due to maintenance of initial permeability of producing formation;
- opportunity to develop non-traditional deposits of hydrocarbons;
- opportunity of target impact on the formation due to directed drilling of controlled radial channels with big length;
- opportunity to perform intensification without impact on casing string cement with significant pressure differential and chemical destruction;
- opportunity to perform intensification by impact on the formation with significant pressure differential or chemical destruction;
- cleaning of the wellbore during its drilling, which allows to efficiently use the technology, both in carbonate and in terrigenous formations;
- opportunity to perform well bottomhole circulation with underbalance and perform geophysical operations in formation interval, perform various types of well workovers without contact of process fluids with producing formation, recover isolating assembly from killed well as required.

Claims

1-5. (canceled)

6. A method of enhanced oil recovery and intensification of production from oil, gas and condensate wells with use of hydromonitor radial underbalance formation penetration, the method comprising the steps of:

(a) milling of a separate window in a casing string for each radial channel for drilling of a radial channel,

(b) installing, in a well,

re-entry guide,

packer,

circulation unit,

disconnector,

a deflector having an internal channel passing through the deflector, wherein the deflector is configured to be spatially oriented in a lower level of radial channel drilling,

a sealing device,

a turning device,

a mechanical anchoring device, and

a high strength tubing,

(c) wellhead sealing,

(d) installing downhole equipment, the downhole equipment comprising:

a hydromonitor nozzle,

a wellbore trajectory control module,

a navigation system,

a work coil tubing section,

a flow re-distribution device,

a check valve,

a supply coil tubing section,

(e) supplying an aerated fluid into an annulus between the high strength tubing and the supply coil tubing section or supplying aerated fluid simultaneously into an annulus between the high strength tubing and the supply coil tubing section and an internal space of the supply coil tubing section or separate injection of fluid and gas into these two spaces, wherein the aerated fluid passes an annulus between the high strength tubing and the supply coil tubing section, the flow re-distribution device, the work coil tubing section, the hydromonitor nozzle and on to the radial channel forming a channel, then the aerated fluid returns with products of rock destruction to the well along the drilled radial channel and comes up on the wellhead along an annulus between high strength tubing and a casing string;

(f) degassing the fluid on a surface, cleaning the fluid of hydrocarbons and products of rock destruction, chemical treating the fluid if required and returning the fluid through a circulation into the well;

(g) passing the hydromonitor nozzle through the sealing device and through the deflector to contact a rock;

(h) hydromonitor underbalance drilling a planned length of the radial channel in a formation using the navigation system and the wellbore trajectory control module, wherein the navigation system is configured to control a position of a wellbore in the formation, wherein the wellbore trajectory control module is configured to ensure wellbore drilling along a designed route;

(i) providing a bottomhole pressure during step (h) the formation, wherein the bottomhole pressure is lower than a reservoir pressure or equal to it and is defined by fluid density reduced due to aeration and, when required, foam generation to needed values, wherein the fluid density is controlled by design ratio between gas and the fluid supplied from the surface with opportunity to change such ratio in compliance with actual bottomhole pressure;

(j) after drilling in step (h), retrieving the work coil tubing section with the hydromonitor nozzle from the formation;

(k) underbalance circulating the fluid in the well (the bottomhole pressure is lower or equal to the reservoir pressure) until a full carryover of cuttings occurs;

(l) re-positioning the deflector to a different plane via activation of the mechanical turning device,

(m) obtaining and changing a wellbore trajectory during radial channel drilling using the navigation system and the wellbore trajectory control module,

(n) repeating a working cycle comprising steps (e)-(m) for a further radial channel.

7. The method of claim 6 further comprising drilling a further level of radial channels after step (n) comprising the steps of:

(o) retrieving the supply coil tubing section and the work coil tubing section from the well;

(p) controlling over pressure in the high strength tubing by means of closing check-valve included into tubing assembly;

(q) unsetting the mechanical anchoring device with the high strength tubing;

controlling over pressure in the annulus between the high strength tubing and the casing string by means of the wellhead sealing device;

(r) retrieving a tubing landing joint;

(s) setting the mechanical anchoring device with the high strength tubing;

(t) running the work coil tubing section with the navigation system, the wellbore trajectory control module, and the hydromonitor nozzle into the well, and

(u) performing steps (d)-(n).

8. The method of claim 6, wherein step (a) comprises full-circle milling of the casing string in intervals of a planned drilling of radial channel.

9. The method of claim 6, wherein after drilling of all radial channels on the well performing following final operations:

(v) retrieval of process equipment from the well,

(w) installation of isolating assembly above intervals of radial formation penetration, which prevents kill fluid contact with producing formation in intervals of radial penetration,

(x) running of production assembly (for flow lift or pump) without well killing in the interval of drilled radial channels.