CN112855092B

CN112855092B - Downhole operation method and perforation short joint for separate production and separate injection

Info

Publication number: CN112855092B
Application number: CN201911100456.4A
Authority: CN
Inventors: 彭汉修; 孙鹏; 伊伟锴; 段友智; 付道明; 吴俊霞
Original assignee: China Petroleum and Chemical Corp; Sinopec Research Institute of Petroleum Engineering
Current assignee: China Petroleum and Chemical Corp; Sinopec Research Institute of Petroleum Engineering
Priority date: 2019-11-12
Filing date: 2019-11-12
Publication date: 2023-01-31
Anticipated expiration: 2039-11-12
Also published as: CN112855092A

Abstract

The invention relates to a downhole operation method and a perforation short joint for separate production and separate injection. The downhole operation method comprises the following steps: running casing into an open hole, the casing comprising a perforation sub, the casing being run to a location where the perforation sub opposes an intended reservoir; and perforating the opposite reservoir formation through the perforation sub to create a flow path between the reservoir formation and the casing lumen. The method for underground operation is beneficial to ensuring the smooth operation of the underground operation.

Description

Downhole operation method and perforation short joint for separate production and separate injection

Technical Field

The invention relates to the technical field of oil and gas well construction operation, in particular to an underground operation method. The invention also relates to a perforation short joint for separate production and separate injection.

Background

In the process of oil and gas exploitation, separate-layer water injection and separate-layer exploitation are often required. Typically, in the art, a production string is run after cementing, which includes tubing and a plurality of packers with corresponding perforation fractures, oil recovery, water injection nipples, etc. disposed on the tubing between the packers. And after the production string is put in place, an annular space between the sleeve and the oil pipe is sealed through the packer. Thereby, a closed annulus is formed downhole. Perforation fracturing, oil recovery, water injection nipples, etc. are located within this enclosed annular segment and opposite the intended reservoir. And then, performing corresponding perforation fracturing, oil extraction and water injection operations through fracturing, oil extraction, a water injection short joint and the like in the closed annular section so as to realize separate layer water injection and separate layer mining.

However, this makes the production string very complicated in structure and the operation of the production string very complicated. In particular, if it is desired to flood or produce a greater number of reservoirs, the above-described structure and operation process will be significantly more repetitive. The complicated structure and operation often easily cause errors and unsmoothness in the working process. In addition, through perforation and fracturing of the production string, jet flow needs to penetrate through an annular space between the casing and the oil pipe, the casing wall and a cement layer between the casing and the reservoir, and finally a perforation or fracturing channel is formed on the reservoir. If the pressure of the jet is not strong enough, the effectiveness of the perforation fracture may become poor. The above problems are very disadvantageous in terms of cost and efficiency of the downhole operation, and are not favorable for the smooth performance of the downhole operation.

Therefore, it is desirable to provide a downhole operation method that facilitates smooth performance of downhole operations.

Disclosure of Invention

In order to solve the problems, the invention provides a downhole operation method which is beneficial to ensuring the smooth operation of downhole operation. The invention also provides a perforation short joint.

According to a first aspect of the present invention, there is provided a method of downhole operation comprising: running a casing into the open hole, the casing comprising a perforation sub, the casing being run to a position where the perforation sub opposes an intended reservoir; and perforating the opposite reservoir through the perforation sub to form a flow path between the reservoir and the casing lumen.

By the downhole operation method, the perforation short joints for perforation can be simultaneously lowered while the casing is lowered. After the casing is run in place, the perforation sub is opposite the reservoir to be perforated. Thus, the formation may be perforated directly by a perforation sub on the casing. With this arrangement, the jet used for perforation can be more easily directed into the formation, most often requiring a portion of the sidewall of the perforating sub and a layer of cement between the casing and the reservoir. Thus, even if the strength of the jet is low, channels for perforation and fracturing can be effectively formed on the reservoir. This method of operation is relatively low cost and highly efficient, and it results in relatively low cost and high efficiency of subsequent operations. Therefore, the underground operation method is beneficial to smooth underground operation.

In one embodiment, the perforation sub is configured to perforate the reservoir by detonation.

In one embodiment, the perforation sub is configured to perforate in response to being pressed into the casing lumen.

In one embodiment, after the flow-through passage is formed, a production string is run in the casing lumen for oil production and/or water injection.

In one embodiment, the flow channel is configured to be selectively opened when oil production and/or water flooding is performed, and where a plurality of different perforation subs are provided for different reservoirs, each of the perforation subs may be opened and closed independently of each other.

According to a second aspect of the present invention there is provided a perforation sub for use as part of a casing, the perforation sub comprising: a cylindrical body configured with a body lumen extending through the cylindrical body at a center in a longitudinal direction; and a perforation mechanism embedded in the sidewall of the tubular body, the perforation mechanism configured to enable perforation to form a flow path between the interior cavity of the tubular body and the reservoir.

In one embodiment, the perforation sub can be used in the above-described downhole method of operation, and/or the perforation mechanism comprises: a housing chamber formed in a side wall of the cylindrical body, an explosive being disposed in the housing chamber, a side wall portion between the explosive and an outer side surface of the cylindrical body being thin enough to be penetrated by the side wall portion upon explosion of the explosive; and a communicating chamber formed in a side wall of the cylindrical body, the communicating chamber communicating between the accommodating chamber and the body inner chamber, the accommodating chamber and the communicating chamber forming part of the flow passage after the explosion of the explosive.

In one embodiment, the communication chamber comprises: the first cavity extends along the longitudinal direction and is communicated with the accommodating cavity; and a second cavity extending in a radial direction at a first end of the first cavity to communicate the first cavity with the body lumen; wherein a piston cavity extending in a longitudinal direction is configured at a first end of the first cavity, a piston being arranged in the piston cavity, in a first state the piston being in the piston cavity such that the first cavity is in communication with the second cavity; in a second state, the piston moves into the first end of the first cavity to block the first and second cavities.

In one embodiment, the explosive is configured to explode in response to the pressure of a fluid in contact therewith.

In one embodiment, the sidewall of the cylindrical body extends radially outward compared to other portions of the sleeve, such that explosives embedded within the containment chamber of the cylindrical body are closer to the reservoir.

In one embodiment, the perforation sub further comprises a control mechanism embedded within the sidewall of the cylindrical body, the control mechanism configured to detect fluid conditions around the perforation sub.

Compared with the prior art, the invention has the advantages that: by the downhole operation method, the perforation short joints for perforation can be simultaneously lowered while the casing is lowered. After the casing is run in place, the perforation sub is opposite the reservoir to be perforated. Thus, the formation may be perforated directly by a perforation sub on the casing. With this arrangement, the jet used for perforation can be more easily directed into the formation, most often requiring a portion of the sidewall of the perforating sub and a layer of cement between the casing and the reservoir. Thus, even if the strength of the jet is low, channels for perforation and fracturing can be effectively formed on the reservoir. This method of operation is relatively low cost and highly efficient, and it results in relatively low cost and high efficiency of subsequent operations. Therefore, the underground operation method is beneficial to smooth underground operation.

Drawings

The invention is described in more detail below with reference to the accompanying drawings. Wherein:

figures 1 to 5 show various states of a method of downhole operation according to an embodiment of the invention; and is

Figure 6 shows a schematic diagram of a perforation sub according to an embodiment of the present invention.

In the drawings, like parts are given like reference numerals. The figures are not drawn to scale.

Detailed Description

The invention will be further explained with reference to the drawings.

Fig. 1-5 show various states of a downhole operation method according to an embodiment of the invention.

As shown in FIG. 1, a downhole operation method according to the present invention begins by running casing 200 into an open hole. The casing 200 includes perforation subs disposed at corresponding locations. One or more perforation subs may be provided as desired. For example, in the embodiment shown in FIG. 1, three

perforation subs

100A, 100B, and 100C are provided, corresponding to

reservoirs

300A, 300B, and 300C, respectively, that require perforation. After casing 200 is run in place, perforation sub 100A is opposite reservoir 300A, perforation sub 100B is opposite reservoir 300B, and perforation sub 100C is opposite reservoir 300C.

After the casing 200 is run in place, a cementing operation may be performed to form a cement layer in the annulus between the casing 200 and the open hole. As such, a layer of cement will fill between the

perforation subs

100A, 100B, and 100C and the

respective reservoirs

300A, 300B, and 300C.

Thereafter, as shown in FIG. 2,

reservoirs

300A, 300B and 300C may be perforated through

perforation subs

100A, 100B and 100C on casing 200. Here, because the perforations are made through a perforation sub on the casing 200, the jet produced only needs to pass through a portion of the sidewall of the perforation sub and the cement layer at most to reach the reservoir. In this way, the perforation depth of the prior art can be achieved with a less intense jet. In other words, deeper perforation results are obtained with jets of the same strength as in the prior art. If the jet strength is greater, the depth of the perforation can be increased very substantially.

In the embodiment shown in FIG. 2,

perforation subs

100A, 100B, and 100C may be actuated to perform a perforating operation by pressing from the wellhead into the interior cavity of casing 200. For example, about 10MPa to 15MPa may be pressed to achieve the perforating operation described above.

In the present invention, the perforation sub preferably effects perforation by means of detonation. Detonation is beneficial to increase the strength of the jet, thereby being beneficial to ensure that the fracture generated by perforation is deep enough into the stratum. This is described in more detail below in conjunction with fig. 6. It should be understood, however, that the perforation sub may be perforated in other ways as desired.

Through the perforating step described above, a flow path may be formed between the reservoir and the interior cavity of the casing 200 that allows fluid in the reservoir to flow into the casing 200.

After perforating, a production string 400 may be run into the casing 200 as shown in FIG. 3.

In a preferred embodiment, the flow channels formed in the perforation sub by the perforation operation are selectively opened and closed. In this case, it is preferred that after perforation, the flow channels on all the perforation subs are closed before running the production string 400, thereby ensuring that the production string 400 runs more smoothly.

After running the production string 400, the reservoir may be run for oil or water injection through the flow-through channels in the perforation sub.

For example, in FIG. 3, the flow channels on the

perforation subs

100A, 100B, and 100C are all open to allow production of hydrocarbons from the respective reservoirs through the production tubing string 400.

For example, in FIG. 4, the flow channels on the

perforation subs

100A and 100C are open and the flow channels on the perforation subs 100B are closed, producing hydrocarbons from the respective reservoirs through the production string 400.

For example, in FIG. 5, the flow paths on the

perforation subs

100A, 100B, and 100C are all open and a waterflooding operation is performed through the production string 400 into the corresponding reservoir. It should be understood that the flow channels of a portion of the

perforation subs

100A, 100B, and 100C may be closed during a waterflooding operation, as desired, to effect waterflooding of a portion of the reservoir.

In the embodiment shown in fig. 3-5, the lower port of the production string 400 may be located above each reservoir. That is, there is no need for the production string 400 to be run to the depth of each reservoir and to provide flow openings substantially opposite each reservoir. However, it should be understood that if the locations between the multiple reservoirs differ significantly, such as the distance between reservoir 300C and reservoir 300A, the production string 400 may be extended through the elevation of reservoir 300A with its lower port above reservoir 300C. In this case, corresponding flow-through openings may be provided in a portion of the production string 400 at the level of the reservoir 300A to produce and/or flood the reservoir 300A.

Additionally, in the downhole methods described above, the production string 400 may be relatively simple in structure and require relatively few actions and functions to be performed. This is very advantageous in reducing the cost of the downhole operation and in improving the efficiency of the downhole operation. Therefore, the smooth operation of the underground operation is favorably ensured.

Figure 6 shows a perforation sub 100 that may be used in the method of downhole operations described above, which may be used as any of the

perforation sub

100A, 100B and 100C of figures 1 to 5.

The perforation sub 100 may comprise a generally cylindrical tubular body 110. The upper and lower ends of the tubular body 110 are connected to the

other casing segments

210, 220 above and below, respectively. A body cavity 111 penetrating the cylindrical body 110 in the longitudinal direction is configured at the center of the cylindrical body 110. The body lumen 111 is part of the cannula lumen.

The perforation sub 100 also includes a perforation mechanism embedded (or buried) within the sidewall of the tubular body 110. The perforation mechanism may include a receiving cavity 114 extending within the sidewall of the tubular body 110 in a radial direction of the tubular body 110. Contained within the containment chamber 114 is explosive 120 for effecting explosive perforations. A first end of the receiving chamber 114 extends toward the outside of the cylindrical body 110 in the radial direction without penetrating the outer surface of the cylindrical body 110. That is, the sidewall of the cylindrical body 110 remains with a corresponding thin wall portion beyond the first end of the receiving chamber 114. The thin wall portion may be constructed separately from the other portions of the cylindrical body 110. For example, the thin-walled portion may be formed by a sleeve, a cover plate, or the like. The material and thickness of the thin-walled portion allows explosives 120 to penetrate the thin-walled portion upon detonation. The thickness of the thin wall portion may be, for example, between about 2mm and about 3mm, which is much less than the thickness of a typical sleeve wall (approximately between 7mm and 8 mm).

With the above arrangement, directed detonation perforation of explosives 120 may be achieved.

Explosives 120 are preferably disposed at the first end of containment chamber 114 so as to be as close or proximate to the thin-walled portion as possible. Alternatively, the explosive 120 may be disposed directly on the thin-walled portion. Thus, the impact and jet generated by the explosion of the explosive 120 more easily act on the thin-walled portion and penetrate the thin-walled portion, the cement layer, and the reservoir.

In the embodiment shown in fig. 6, the receiving chamber 114 is configured with a conical or truncated conical shape, the cross section of which gradually increases in the radially outward direction. Such containment chamber 114 facilitates the relative directional impingement and jetting of explosives 120 toward the reservoir upon detonation, thereby facilitating penetration of thin-walled portions, cement layers, and the reservoir.

In addition, the explosion mechanism further includes a communication chamber that communicates between the accommodation chamber 114 and the main body inner chamber 111. Thus, by increasing the pressure of the fluid in the body cavity 111 by uphole pressure, the pressure of the fluid in the receiving cavity 114 may be correspondingly increased. Explosive 120 may explode in response to an increase in the pressure of the fluid surrounding it (i.e., an increase in the pressure in the body cavity). By the above pressurization, it is possible to achieve an increase in the pressure of the fluid surrounding the explosive 120 of about 10MPa to 15MPa, by which the explosive 120 explodes.

In the embodiment shown in fig. 6, the communication chamber includes a first chamber body 113 extending in the longitudinal direction and communicating with a second end of the accommodation chamber 114 opposite to the first end. The communicating chamber further includes a second chamber 112 extending in a radial direction, and one end of the second chamber 112 communicates with the first chamber 113 and the other end communicates with the main body inner chamber 111. Thus, the body cavity 111 can communicate with the accommodating cavity 114 through the second cavity 112 and the first cavity 113.

In the embodiment shown in fig. 6, a plurality of receiving cavities 114 spaced apart from each other are embedded in the sidewall of the tubular body 110 in the longitudinal direction, and a respective explosive 120 is disposed in each receiving cavity 114 for forming a plurality of perforations in a section of the reservoir. The first cavity 113 extending in the longitudinal direction may communicate with each of the plurality of receiving cavities 114 to achieve fluid exchange.

At a first end (preferably a lower end) of the first cavity 113 extending in the longitudinal direction, a piston cavity is configured which further extends in the longitudinal direction. A piston 130 is housed within the piston chamber.

In the first state, the piston 130 is within the piston chamber 130. At this time, the first and

second cavities

113 and 112 communicate with each other, and the receiving cavity 114 communicates with the main body cavity 111.

In the second state, the piston 130 moves in the longitudinal direction at least partially out of the piston chamber 130 and at least partially into the first chamber 113, overlapping the second chamber 112. At this time, the first cavity 113 and the second cavity 112 are isolated, and the accommodating cavity 114 is not communicated with the main body inner cavity 111.

For example, the piston 130 may be driven to move in a longitudinal direction by a motor 130 embedded in a sidewall of the cylindrical body 110. The motor 130 may drive the piston 130 to move, for example, by way of a screw drive.

In one embodiment, the piston 130 is in a first state in an initial state, i.e., the first fluid 113 and the second chamber 112 are maintained in communication. Thus, the well fluid always fills the body inner cavity 111, the second cavity 112, the first cavity 113 and the accommodation cavity 114. After the detonation of the pressurization, a communication channel is formed between the body lumen 111 (a portion of the sleeve lumen) and the reservoir. The communication relationship between the first and

second chambers

113 and 112 is changed by the piston 130 moving between the first and second states. From which it is decided whether to recover oil and/or flood the corresponding reservoir. The operation of this embodiment is simple. From the aspect, the cost of the operation process is reduced, and the efficiency of the operation process is improved.

In another embodiment, the piston 130 is in the second state in the initial state, i.e., the first cavity 113 and the second cavity 112 are isolated. Thus, the body lumen 111 and the receiving lumen 114 are not in fluid communication during running of the cannula 200. In this case, the pressure fluctuation of the fluid in body cavity 111 does not affect explosive 120 in accommodation cavity 114, thereby facilitating the avoidance of an unintended explosion. After the casing 200 is run in place, and before perforation is required, the first and

second cavities

113 and 112 are put into communication by the movement of the piston 130 to allow perforation by means of pressing. After the detonation of the pressure, a communication channel is formed between the body lumen 111 (part of the sleeve lumen) and the reservoir. The communication relationship between the first and

second chambers

113 and 112 is changed by the piston 130 moving between the first and second states. Thereby determining whether to recover and/or flood the corresponding reservoir. Such an embodiment is more advantageous in ensuring smooth and accurate perforation operations. From the aspect, the cost of the operation process is reduced, and the efficiency of the operation process is improved. It should be understood that in such an embodiment, the receiving cavity 114 may itself be filled with a corresponding fluid.

As shown in fig. 6, the cylindrical body 110 preferably has a relatively large outer diameter so that the first end of the receiving cavity 113 can extend more radially outward close to the reservoir. As can be seen clearly from fig. 6, the tubular body 110 projects radially further outward than the

other jacket segments

210, 220 above and below. Therefore, the distance between the reservoir and the explosive 120 is reduced, which is beneficial to improving the effect of the explosive 120 on the reservoir. In particular, the above arrangement also enables a reduction in the thickness of the cement layer between the tubular body 110 and the reservoir after cementing. This further contributes to the effect of the explosives 120 on the reservoir.

Further, a control mechanism 150 and a data transmission mechanism 160 may be embedded in the tubular body 110. The control mechanism 150 may be used to detect a parameter (e.g., property, temperature, flow rate, flow velocity, flow pressure, etc.) of the fluid flowing through the flow-through channel and communicate the parameter to the data transmission mechanism 160. The data transmission mechanism 160 may be used to transmit the corresponding parameters to a receiving mechanism at the surface. An operator at the surface, after receiving the parameters via the receiving means, may control the motor 140 via the control means 150 to move the piston 130 between the first state and the second state in accordance with the respective parameters, controlling the opening and closing of the flow passage.

The data transmission mechanism 160 may be, for example, an ultrasonic or microwave generator, or any other wired or wireless transmission mechanism.

Further, a battery 170 may be embedded in the tubular body 110. The battery 170 may provide power to the control mechanism 150, the data transmission mechanism 160, and the motor 140 to ensure their smooth operation.

The underground operation method is suitable for performing the operation processes of well cementation, perforation fracturing, separate-layer oil extraction, separate-layer water injection and the like, and is particularly suitable for operating a new well. The underground operation method and the perforation short joint can be used for perforating quickly and efficiently and performing subsequent operation processes such as layered oil extraction, layered water injection and the like.

While the invention has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In particular, the technical features mentioned in the embodiments can be combined in any way as long as there is no structural conflict. It is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A method of downhole operations comprising:

running casing into an open hole, the casing comprising a perforation sub, the casing being run to a location where the perforation sub opposes an intended reservoir; and

perforating an opposing reservoir through the perforation sub to create a flow path between the reservoir and the casing lumen,

wherein the perforation sub comprises a tubular body configured with a body lumen extending through the tubular body centrally in a longitudinal direction, and a perforation mechanism embedded within a side wall of the tubular body, the perforation mechanism being configured to be perforated to form a communication channel between the lumen of the tubular body and the reservoir, the perforation mechanism comprising a receiving chamber and a communication chamber formed within the side wall of the tubular body, an explosive being disposed within the receiving chamber, a first end of the receiving chamber extending in a radial direction towards the outside of the tubular body but not through the outside surface of the tubular body, a side wall portion between the explosive and the outside surface of the tubular body being sufficiently thin to allow the side wall portion to be penetrated upon detonation of the explosive, the explosive being disposed at the first end of the receiving chamber, the receiving chamber having a cross-section that gradually increases in a radially outward direction, the communication chamber being in communication between the receiving chamber and the body lumen, the communication chamber comprising a first chamber extending in the longitudinal direction and a second chamber communicating the first chamber with the body lumen, the first chamber being in communication with the receiving chamber, the second chamber extending in the radial direction at the first end; the explosive substance is capable of exploding in response to an increase in the pressure of the fluid surrounding it, and the accommodation chamber and the communication chamber form part of the communication passage after the explosive substance explodes.

2. A method of operating downhole according to claim 1, wherein after the formation of the flow-through passage, a production string is lowered into the casing inner cavity for oil production and/or water injection.

3. A downhole operation method according to claim 2, wherein the flow channel is configured to be selectively opened when oil production and/or water flooding is performed,

where a plurality of different perforation subs are provided for different reservoirs, each may be opened and closed independently of the other.

4. A downhole operation method according to claim 1, wherein a piston cavity extending in a longitudinal direction is configured at a first end of the first cavity, a piston being arranged in the piston cavity,

in a first state, the piston is in the piston cavity, so that the first cavity is communicated with the second cavity;

in a second state, the piston moves into the first end of the first cavity to block the first and second cavities.

5. A downhole operation method according to claim 4, wherein the side wall of the cylindrical body extends radially outwards compared to the rest of the casing, such that explosives embedded in the containment chamber of the cylindrical body are closer to the reservoir.

6. A method of operating downhole according to claim 4 or 5, wherein the perforation sub further comprises a control mechanism embedded in a sidewall of the cylindrical body, the control mechanism being configured to detect a fluid condition around the perforation sub.