RU2848534C1 - Device for preparing a well for hydrocarbon production after hydraulic fracturing - Google Patents

Abstract

FIELD: hydrocarbon production.

SUBSTANCE: invention can be used to treat a productive formation after hydraulic fracturing (HF). The device contains a jet pump designed to be connected and disconnected from the annular space by means of a sealing sleeve, a pass-through packer, and an implosion unit. The jet pump housing is equipped with a check valve, a diffuser and a nozzle, which are connected to each other through a mixing chamber, which is connected to the check valve through a channel made in the housing. The sealing sleeve is equipped with a flow channel, within which radial holes are made. The pass-through packer is located under the jet pump. The implosion unit is located under the packer and includes a circulation unit connected in series, made in the form of a hollow body with an opening on its side surface with the possibility of closing the opening, a throttle, an implosion valve, a container for collecting mechanical contaminants, a check valve with a shut-off ball, and a destruction unit in the form of a hollow pipe. The implosion valve contains a hollow body with a passage in the lower part, in which a hollow rod with radial openings and a plug in the lower part is installed with the possibility of axial movement. The internal cavities of the jet pump, packer and implosion unit form the common internal cavity of the device.

EFFECT: efficiency of well preparation after hydraulic fracturing is increased by reducing the technological time required, the negative impact on the formation is reduced, and the inflow volume from the formation is increased.

1 cl, 4 dwg

Description

The invention relates to mining, in particular to the extraction of hydrocarbons, namely to the development and cleaning of wells of various designs using the implosion method, and can be used for processing a productive formation after hydraulic fracturing (HF) in several stages in one tripping operation.

Technological measures to prepare a well for hydrocarbon production after hydraulic fracturing primarily include normalizing the wellbore bottomhole, which involves breaking up and removing the sand-proppant plug that forms during hydraulic fracturing and impedes the lowering of process equipment. Then, well completion involves removing the fracturing fluid from the formation, which negatively impacts the formation's filtering properties, and stimulating fluid inflow from the formation. The fracturing fluid is a gel that transports suspended proppant particles into the formation. The fracturing fluid is removed to prevent colmatation and plugging of the rock's pore space with its decomposition products, which occurs shortly after hydraulic fracturing.

Improving the technological efficiency of near-wellbore formation treatment can be achieved through the use of implosion-based wellbore cleanout technologies. The sequential order of these operations allows them to be performed in a single well trip. This allows for higher drawdown during well completion, expands the technological capabilities of the equipment, and reduces the time required to prepare the well for production after hydraulic fracturing. To effectively complete a well after hydraulic fracturing, it is necessary to extract the previously injected fracturing fluid from the formation and induce fluid inflow from the formation. Since well completion speed is directly dependent on the performance of the jet pump, the use of an implosion-based device can improve equipment efficiency, particularly reducing completion time and wellbore cleanout of proppant plugs.

A device for the comprehensive treatment of a productive formation is known. It is lowered into a wellbore on tubing and consists of a jet pump, a continuous packer, a template, and a scraper with knives designed to clean the inner surface of the production string from drill mud, cement, rust, paraffin, perforation burrs, and other contaminants (Russian Federation Patent for Utility Model No. 215773, E21B 43/00, E21B 37/00, December 26, 2022). A spherical hinge joint is installed between the packer and the template, reducing the bending rigidity of the assembly. The jet pump comprises a hollow cylindrical body in which a sealing sleeve is placed with axial movement. The outer surface of the sealing sleeve is provided with a groove within which radial holes are made. The jet pump housing contains a check valve consisting of a ball and seat, a nozzle with a channel leading to it, a diffuser, and a mixing chamber. A projection is provided at the bottom of the housing. The check valve is connected to the mixing chamber via a separate radial channel. The bushing is retained in the pump housing by a breakable element.

A disadvantage of this device is the need to clean and collect contaminants using reverse circulation (RC) flushing—forcing fluid through the annulus. This limits its use in wells with low formation pressure (formation pressure below the hydrostatic pressure of the wellbore fluid column). In such wells, reverse circulation will result in the formation absorbing the flushing fluid, leading to the following negative consequences: saturation of the oil-bearing formation with water, forming colmatating oil-water emulsions; consumption of large volumes of water during flushing due to absorption by the formation, requiring the constant use of additional equipment to deliver water to the well; all the fluid absorbed by the formation must be recovered using the jet pump included in the device, which will increase the overall operating time of the device.

The closest in technical essence to the claimed technical solution is a device for influencing and cleaning the near-wellbore zone of a well (RU Patent for Invention No. 2213859, E21B 43/25, E21B 37/00, 2001). The device comprises a liner, a check valve, and an implosion device in the form of a cylinder with a hollow plunger with holes in the side walls, mounted in series on the tubing and connected to the pipes. The device is equipped with a hydraulic spool-type decolmator installed between the check valve and the implosion device. The hollow plunger is equipped with a check valve designed to communicate with the plunger cavity under the plunger when fluid is supplied to the tubing. The device is equipped with a jet pump mounted on the tubing so that its inlet ports are blocked by a through-hole plug installed in the tubing, and the outlet nozzle communicates with the wellbore. The through-hole plug is removable and a blind plug can be installed in the tubing. The device has a packer installed between a decollmator, which is part of a spool device comprising a cylinder with holes in the form of a stator, a rotating spool in the form of a rotor with tangential slots, and an implosion device. The liner is designed with slots in the side walls and a plugged end containing a chamber housing a downhole pressure gauge. Mechanical cleaning is performed after wave stimulation of the near-wellbore zone (BWZ) and injection of chemical reagents to create a depression in the formation. Mechanical cleaning of the wellbore zone is performed by swabbing to empty the tubing, lowering the fluid level in the tubing to a specified depth, taking into account the required formation drawdown. To clean the wellbore zone using an implosion device, the assembly is gently unloaded downhole. The implosion device's plunger openings cause the pressure drop to release wellbore fluid containing mechanical impurities through the liner and check valve, allowing the wellbore fluid to flow into the chamber from the tubing. Next, reverse flushing is performed using a flushing unit (from the annulus to the tubing) to clean the tubing space of dirt and decolmatation products.

The device's unique feature is that after wave stimulation of the formation, mechanical cleaning of the bottomhole zone (BZ), and reverse circulation, inflow is stimulated using a jet pump. A through plug is first removed with a mobile winch. A ball is dropped, a blind plug is installed with the same winch, and the packer is set, sealing the annulus. The jet pump develops the formation by creating alternating depressions with circulation through the tubing into the annulus until a stable inflow of formation fluid is achieved. Thus, a single trip of the hanger sequentially involves treating the BZ with a decollmator, mechanical cleaning, and additional cleaning of the formation and bottomhole with an implosion device, creating multiple alternating depressions (drawdown - overbalance), as well as development and inflow stimulation using a jet pump, with pressure changes recorded using an electronic pressure gauge.

The disadvantage of the closest analogue is that in order to empty the tubing that provides the implosive effect on the wellbore zone, swabbing is carried out, which requires additional equipment - cable equipment of the geophysical crew, energy costs for it and the expenditure of process time for swabbing.

Another disadvantage of the analogue is the low cleaning efficiency, which consists in the impossibility of cleaning the bottom of the well from sand and proppant plugs, since the lower part of the device is plugged with a non-passable end and does not have an aggressive destructive structure at the lower end.

An additional disadvantage of the analogue is the design of the device, which necessitates reverse flushing, which imposes restrictions on the use of the device in wells with low formation pressure, in which, during reverse flushing, the absorption of the drilling fluid by the formation is inevitable, the formation of water-oil emulsions in the formation, which aggravate colmatation and impair the permeability of the bottomhole formation zone.

A common drawback of known devices is low technological efficiency due to additional associated energy and time costs for performing each technological operation for the initial impact on the wellbore zone and subsequent cleaning of the formation and wellbore.

The technical result of the claimed invention is to increase the efficiency of well preparation after hydraulic fracturing by reducing the cost of process time, reducing the negative impact on the formation and increasing the volume of inflow from the formation.

The technical result is achieved in that in a device for preparing a well for the production of hydrocarbons after hydraulic fracturing, comprising a jet pump configured to communicate and disconnect with the annular space by means of a sealing sleeve, a through-hole packer, an implosion unit, according to the invention, the housing of the jet pump is provided with a check valve, a diffuser and a nozzle communicating through a mixing chamber, wherein the mixing chamber communicates with the check valve by a channel made in the housing, and the sealing sleeve is provided with a groove within which radial holes are made, the through-hole packer is located under the jet pump, the implosion unit is located under the packer and includes a circulation unit connected in series, made in the form of a hollow housing with an opening on its side surface with the possibility of closing the opening, a choke, an implosion valve, a container for collecting mechanical impurities, a check valve with a shut-off ball, a destructive unit in the form of a pipe section, wherein the implosion valve contains a hollow body with a groove in the lower part, in which a hollow rod with radial holes and a plug in the lower part is installed with the possibility of axial movement, while the internal cavities of the jet pump, packer and implosion unit form a common internal cavity of the device.

The technical result is achieved by a device for preparing a well for hydrocarbon production after hydraulic fracturing, which includes a jet pump capable of communicating with and disconnecting from the annulus and an implosion unit. These units enable the wellbore and reservoir to be cleaned using fluid streams designed so that, when each stream sequentially impacts contaminants in the wellbore and near-wellbore zone (BWZ), their synergistic effect is enhanced, aimed at cleaning the wellbore and creating deeper depressions in the formation. These fluid streams simultaneously remove fragments of the broken proppant plug and hydraulic fracturing fluid from the reservoir, increasing the efficiency of wellbore preparation after hydraulic fracturing by saving time and energy. The formation of such flows is possible due to the jet pump design of the claimed device enabling communication and isolation between the device cavity and the annulus. The implosion unit, which comprises a circulation unit, throttle, implosion valve, waste collection container, ball check valve, and demolition tool, installed in series, includes elements that enable communication and isolation between the device cavity and the annulus. For example, in the circulation unit of the implosion unit, a side opening in the hollow body is designed to open, and in the implosion valve of the implosion unit, a hollow rod with radial holes is installed in the hollow body. The axial movement of the rod ensures communication and isolation between the internal cavity of the device and the annulus.

Thanks to the proposed device's ability to communicate and isolate its cavity from the borehole cavity, the device is initially lowered into the well completely sealed and empty. Once the cavities are isolated, eliminating the need for additional equipment and the time-consuming task of emptying the tubing by swabbing, allowing for formation drawdown and the beginning of cleaning the wellbore bottomhole of the proppant plug immediately after lowering. The closest comparable device incorporates a decollater, which requires fluid to be pumped through it to operate, inevitably filling the tubing with fluid. Swabbing in the closest comparable device is necessary to empty the tubing after the decollater has operated, ensuring implosion and formation drawdown when the empty tubing is filled with wellbore fluid through the implosion device. The proposed device eliminates the decollater, allowing the tubing and device to be lowered into the wellbore immediately empty, eliminating the need for time and resources spent on swabbing.

Equipping the proposed device with a disruptor, compared to the prototype, provides an additional opportunity to clean the well of dense proppant plugs. Thanks to its design, the proposed device effectively cleans the well and the bottomhole zone (BZ) in both normal and low-pressure wells without the use of reverse circulation or the unwanted clogging of the BZ with oil-water emulsions.

Thus, the use of implosion wellbore cleaning in conjunction with a jet pump allows for the extraction of fracturing fluid from the formation to begin already at the wellbore cleaning stage without additional energy expenditure, thereby increasing the volume of fluid extracted from the formation while simultaneously saving time by performing two different technological operations in a single well operation.

Fig. 1 shows a general view of a device for preparing a well for hydrocarbon production after hydraulic fracturing.

Fig. 2 shows a longitudinal section A-A of the device during the process of implosive cleaning of the well bottom from the proppant plug and the primary selection of hydraulic fracturing fluid from the bottomhole zone.

Fig. 3 shows a longitudinal section of the device during the process of secondary extraction of hydraulic fracturing fluid from the bottomhole formation zone.

Fig. 4 shows a cross-section B-B of a jet pump showing the channel from the check valve to the mixing chamber.

A device for preparing a well for oil and/or gas production after hydraulic fracturing is lowered into the well using tubing 1. The internal cavities of the tubing and device are sealed and not filled with liquid. The device comprises a jet pump 2, a pass-through packer 3, and an implosion unit 4 (Fig. 1).

The jet pump 2 comprises a hollow body 5 in which a check valve 6 is installed consisting of a ball 7, a seat 8 and a channel of the check valve 9. In addition, a channel 10 is formed in the hollow body of the jet pump and a nozzle 11 is installed, connected through a mixing chamber 12 with a diffuser 13. The body of the jet pump 2 is provided with a channel 14, providing a hydraulic connection of the channel 9 of the check valve 6 with the mixing chamber 12. In the cavity of the jet pump 2, a sealing sleeve 15 is placed with the possibility of axial movement, on the outer surface of which a groove 16 with radial holes 17 made on it is made. In addition, the jet pump 2 is provided with a destructible element 18, fixing the sealing sleeve 15 in the body 5 of the jet pump 2.

A standard downhole packer, such as the 5POM-PK packer manufactured by JSC Sibneftemash, can be used as the downhole packer 3. (https://www.sibneftemash.ru/products/downhole-equipment/packer-5POM-PK/).

The implosion unit 4 contains a circulation unit 21, a throttle 22, an implosion valve 23, a container 24 for collecting waste, a check valve 25 with a ball 26 and a destructive tool 27, including a hollow pipe 28, installed in series.

The circulation unit 21 consists of a hollow housing 29, in which a bushing 31 is installed, while in the side surface of the housing there is an opening 30, hermetically sealed by the bushing 31. In the transport position of the device, the bushing 31 in the housing 29 of the circulation unit 21 is fixed by a destructible element 32.

Choke 22 is a unit with a narrowed internal flow cross-section that, when the internal cavity of the device and the tubing are filled with wellbore fluid, restricts its flow while sucking contaminants from the wellbore bottom. Choke 22 extends the useful life of implosion unit 4, allowing it to be used, among other things, for breaking the proppant plug with a breaking tool.

The implosion valve 23 consists of a hollow body 33, in the lower part of which a groove 34 is made, while in the cavity of the body a hollow rod 35 is installed with a lower end in the form of a plug 36, near which radial holes 37 are made in the area of the groove 34. In addition, on the inner surface of the body 33 of the implosion valve a stop 38 is made for fixing the rod 35 at the extreme lower point of the stroke.

The internal cavities of the jet pump 2, packer 3 and implosion unit 4 form a common internal cavity 44 of the device.

The device for preparing a well for hydrocarbon production after hydraulic fracturing works as follows.

The device, consisting of a jet pump 2, a through packer 3, an implosion unit 4 containing a circulation unit 21, a choke 22, an implosion valve 23, a container 24, a check valve 25 and a destructive tool 27, is lowered onto a tubing 1 into the well.

When lowering the device, the through-hole packer 3 is in the transport position, the sealing sleeve 15 of the jet pump 2 is in the upper position, blocking the channel 10 to the nozzle 11, which ensures a hermetically sealed separation of the jet pump 2 from the annular space.

In addition, the internal cavity 44 of the device is hermetically sealed from the wellhead to the implosion valve 23, which allows the device to be lowered into the well without filling it with liquid and keeping it and the tubing 1 empty, facilitating the lowering and ensuring the saving of energy resources.

When unloading the weight of the device and tubing 1 onto the proppant plug 45, the latter is divided into fragments using a destructive tool 27, wherein the rod 35 occupies a lower position, extending from the body 33 to the stop 38, made on the inner surface of the body of the implosion valve 23, wherein the plug 36 of the rod 35, being located in the zone of the groove 34, opens the holes 37, due to which a hydraulic connection is provided between the internal cavity of the device and the tubing with the annular space (Fig. 2).

Through the destructive device 27 and the openings 37, the empty cavity 44 of the device is filled with well fluid 41, which, capturing fragments of the proppant plug, transfers them to the container 24, cleaning the bottom of the well, while due to the effect of communicating vessels when the cavity of the device is filled with well fluid 41, its level in the annular space of the well decreases, which leads to a decrease in the hydrostatic pressure of the well fluid 41 on the formation, the occurrence of depression and the induction of an influx from the formation, which tends to restore the previous static level of the liquid in the well.

Thus, the primary extraction of hydraulic fracturing fluid from the formation is carried out simultaneously with cleaning the well bottom, the volume of which will be equal to the volume of the empty cavity of the device.

After cleaning the bottom of the well, the device is raised until the through packer 3 is positioned above the level of the productive formation and it is moved into the working position, whereby, under the action of gravity, the body 33, container 24, check valve 25 and destructive device 27 move downwards relative to the rod 35, blocking the radial openings 37 and moving the implosion valve 23 into the closed position, in which the cavity 44 of the device again becomes hermetically sealed from the annular space (Fig. 3).

The isolation of the annular space by the through-hole packer 3 does not allow the well fluid from the above-packer zone to flow into the below-packer zone.

Next, a small ball 39 is dropped into the tubing 1, which penetrates through the cavity 44 of the device into the circulation unit 21 and, interacting with the seat 31, knocks down the destructible element 32, the seat 31 moves downwards, opening the hole 30, due to which a hydraulic connection is provided between the internal cavity of the device and the annular sub-packer space and conditions are created for the circulation of the working fluid through the jet pump.

Then, a large ball 40 is dropped into the tubing 1, which penetrates into the body 5 of the jet pump 2, interacts with the sealing sleeve 15, knocks down the destructible element 18, displacing the sleeve 15 to the projection 46. This ensures a hydraulic connection between the internal cavity of the device 44 and the tubing 1 with the above-packer annular space through the radial openings 17 made in the groove 16 of the sealing sleeve 15, the channels 9 and 10 of the jet pump 2 and creates conditions for the circulation of the working fluid 42 through the nozzle 11, the mixing chamber 12, the diffuser 13 and the above-packer annular space, simultaneously ensuring the isolation of the internal cavity of the tubing 1 from the sub-packer space (Fig. 3).

Next, the hydraulic fracturing fluid is selected by feeding the working fluid 42 into the tubing 1 under pressure, which through the channel 10, the nozzle 11, the mixing chamber 12, the diffuser 13 of the jet pump 2 enters the above-packer annular space and the wellhead, thereby creating a low-pressure region in the mixing chamber 12, into which the hydraulic fracturing fluid 43 exiting the productive formation rushes through the below-packer annular space and the opening 30.

Moving through the internal cavity 44 of the device, the hydraulic fracturing fluid 43 mixes with the working fluid 42 in the mixing chamber 12, and the formed common flow rises through the above-packer annular space to the surface.

Upon completion of well development, the flow packer 3 is deactivated, transferred to the transport position, and the device is then lifted.

Thus, the claimed invention allows for the efficient preparation of a well for hydrocarbon production by combining bottomhole cleaning and well development in a single technological operation, as well as by additionally extracting hydraulic fracturing fluid during bottomhole cleaning.

Claims (1)

A device for preparing a well for the production of hydrocarbons after hydraulic fracturing, comprising a jet pump configured to communicate with and disconnect from the annulus by means of a sealing sleeve, a through-hole packer, an implosion unit, characterized in that the housing of the jet pump is provided with a check valve, a diffuser and a nozzle communicating through a mixing chamber, wherein the mixing chamber communicates with the check valve by a channel formed in the housing, and the sealing sleeve is provided with a groove within which radial holes are made, the through-hole packer is located under the jet pump, the implosion unit is located under the packer and includes a circulation unit connected in series, made in the form of a hollow housing with an opening on its side surface with the possibility of closing the opening, a choke, an implosion valve, a container for collecting mechanical impurities, a check valve with a shut-off ball, a destruction unit in the form of a section of pipe, wherein the implosion valve contains a hollow housing with a groove in the lower part, in which a hollow rod with radial holes and a plug in the lower part is installed with the possibility of axial movement, while the internal cavities of the jet pump, packer and implosion unit form a common internal cavity of the device.