WO2016008400A1

WO2016008400A1 - Underground opening self-locking well casing pipe centering device

Info

Publication number: WO2016008400A1
Application number: PCT/CN2015/083917
Authority: WO
Inventors: 夏庆华
Original assignee: 大庆福斯特科技开发有限公司
Priority date: 2014-07-16
Filing date: 2015-07-14
Publication date: 2016-01-21
Also published as: SG11201601868RA; CN104234647A; EP3170964A4; EP3170964A1; US20160215574A1; CN104234647B

Abstract

An underground opening self-locking well casing pipe centering device, comprising a connection part I (1) and a connection part II (2) located at two ends; a centering support part (3) is arranged between connection part I (1) and connection part II (2), and comprises a hollow connection body (5); and at least three level-N piston-type self-locking support devices are uniformly arranged on the circumference of the connection body, extending outward gradually under pressure, and N≥2. The underground opening self-locking well casing pipe centering device has the following advantages: 1, employing an integrated threaded structure; 2, employing an underground opening self-locking support structure; 3, an arc-shaped support cap ensures large support force and reduces damage to a well wall.

Description

Underground self-locking casing centering device

Technical field

The present invention relates to a centering device capable of centering a casing in a wellbore.

Background technique

With the continuous development of the petroleum industry and the pursuit of high oil and gas layer productivity, the requirements for cementing quality are getting higher and higher. The middle degree of casing in the wellbore is one of the decisive factors for the quality of oil and gas well cementing. . Therefore, how to accurately grasp the centering condition of the casing string in the well and how to improve the displacement efficiency in the cementing and cementing process is an urgent problem to be solved in the oilfield. The cementing quality in the cementing process is determined by the cementing displacement efficiency. However, the casing centering degree in the wellbore is an important factor affecting the efficiency of cementing displacement. The centering degree is poor, and it is easy to form wide and narrow sides. When the cement replaces the drilling fluid, the cement slurry is easy to touch the wide side and the narrow side is drilled. The fluid displacement is not replaced or the replacement is not clean, which affects the quality of the cementing. Therefore, the use of the centering device plays a crucial role in whether the casing can be centered in the wellbore.

The existing conventional centering devices are basically divided into two categories: one is a flexible centering device, the other is a rigid centering device, and the elastic centering device is designed according to a spring principle, which has the advantages of high resetting force and manufacturing process. Simple, low price, the disadvantage is that it will produce a large driving force when used, and the damage rate to the wellbore wall is high, which affects the normal running of the casing.

The rigid centering device is further divided into a semi-rigid centering device, a spiral rigid centering device and a roller type rigid centering device. The advantage of the rigid centering device is its high support and low starting or displacement forces, allowing the casing to run smoothly and maintain a high centering. The disadvantage is that the rigid centering device has higher requirements on the wellbore and cannot have a reduced diameter section. At the same time, the rigid centering device increases the rigidity of the pipe string, causes difficulty in casing, and has high manufacturing cost, complicated manufacturing process, and unstable reliability, and thus its usage is limited.

There is also an elastic centering device for starting downhole. Although it is down to the well, the spring piece is opened by the pressure difference, and the bow spring piece generates sufficient restoring force to achieve a centering effect, but the starting pressure of the centering device is difficult. Control, the maximum starting power is higher, so it is less used.

Summary of the invention

It is an object of the present invention to provide a casing centering device that is activated after a lower well with a lower starting force.

In order to achieve the above object, the technical solution of the present invention provides a downhole self-locking casing. The middle device comprises a connecting portion 1 and a connecting portion 2 at both ends, and a central supporting portion is arranged between the connecting portion 1 and the connecting portion 2. The central supporting portion comprises a hollow connecting body, and at least the circumferential direction of the connecting body is evenly distributed. Three N-stage piston type self-locking support devices extending step by step under pressure, N≥2;

Each N-stage piston type self-locking support device comprises a support body shell fixed on the coupling body and an N-stage support body composed of a first-stage support body and an N-th stage support body, and the first-stage support body and the support body shell slide Cooperating, the N-th support body and the first-stage support body are sequentially slidingly matched to each other, so that the N-stage support body can be extended step by step under the pressure from the N-th support body, and the N-th support body and the N-th support body A support portion for contacting the well wall support is disposed at an end of the support body facing away from the support wall, and a rupture ring is formed at a bottom of the first stage support body to the Nth stage support body, and the first stage support body is caused by the rupture ring The starting pressure of the N-th support is gradually changed from large to small.

Preferably, the first-stage support body of each of the N-stage piston type self-locking support devices is nested in the support body shell, and the N-th support body and the first-stage support body are sequentially nested in two adjacent stages. Wherein, the k-th support is nested in the k-1th support, k=2, . . . , N.

Preferably, the rupture ring on the current support has an interference fit with the inner wall of the adjacent support body, and the rupture ring on the first stage support has an interference fit with the inner wall of the support body.

Preferably, in each of the N-stage piston type self-locking support devices, at least one N-th stage ratchet-shaped positioning groove is provided on an outer circumferential surface of the N-th stage support body, and the N-1th level support is provided. The outer circumferential surface of the body to the first-stage support body is respectively provided with at least one ratchet-shaped positioning groove, and a C-shaped positioning self-locking ring is respectively disposed on the inner wall of the N-1th support body to the first-stage support body, wherein The outer circumferential surface of the j-th support body is provided with at least one j-th grade ratchet-shaped positioning groove, and a j+1th-order C-shaped positioning self-locking ring is provided on the inner wall thereof, j=1,...,N-1 The Nth-stage ratchet-shaped positioning groove cooperates with the N-1th-order C-shaped positioning self-locking ring, and the j-th stage ratchet-shaped positioning groove cooperates with the j-th C-shaped positioning self-locking ring, and the first stage is positioned from The lock ring is disposed on an inner wall of the support body casing.

Preferably, in each of the N-stage piston type self-locking support devices, adjacent two support bodies and the first-stage support body and the support body shell are respectively sealed by a seal ring.

Preferably, the connecting portion 1 and the connecting portion 2 both adopt a thread structure connected to the sleeve.

Preferably, the portion of the support portion that is in contact with the well wall support is a semi-arc support contact cap.

The invention has the following advantages:

1. The overall structure using threaded joints

In the existing casing centering device, all the elastic centering devices and the bushings are used on the outside of the casing. In actual use, as the casing is lowered, the lowering force of the centering device is compared. Large, centered device will move along the surface of the casing, or it will increase the tensile strength of the pipe when the coupling is placed at the coupling, which will easily cause damage to the threaded connection of the casing, while the rigid centering device is somewhat In the form of a coupling thread with the bushing, this in turn increases the number of couplings and increases the cost of production. The design adopts the integral structure of the standard internal and external threads and the sleeves at both ends, which is equivalent to adding a coupling hoop. The structure of the connection not only facilitates the on-site installation of the centering device, but also increases the production cost. And the length of the entire centering device is short, does not increase the rigidity of the pipe string, and is extremely effective in the use of high-angle wells and horizontal wells. In addition to the conventional LTC thread, the coupling thread can also be processed into a gas-tight special thread, which greatly improves the joint strength and sealing performance of the centering device and the sleeve. The overall structure of the central structure of the design is more than 12,000 psi, which meets the technical requirements of airtight special buckle.

2, the use of downhole start self-locking support structure

(1) Downhole starting support

As a rigid centering device, the advantage of the downhole starting type is that the bushing force does not increase, and the operation of the casing is extremely convenient, but the existing downhole starting type centering device flattens the spring piece from the steel belt attached thereto. , fixed together, the steel belt is controlled by a locking device. After the casing is lowered, the locking device is opened by the pressure difference to open the steel belt, and the spring bow is released, because the spring arch has a large elastic force when flattened. When starting, the steel belt is difficult to ensure smooth opening under the force of force, so the centering effect is difficult to control, and the piston type support form adopted in this design, the N-level support body is all inside the centering device when not opened, when inside the tube When the pressure increases, the N-th support body starts to start first due to the difference in the surface area of the piston bottom. After the position is reached, the stages are sequentially started up to the first stage. When the N-th support is started, the support piston is started only in the casing. Pressure related, has nothing to do with other factors. When the pressure in the casing reaches 1500-2000 psi, the N-th support will start and generate a support force of >4000N. This support force (also the minimum reset force) is much higher than the standard value (standard value 2758N). The performance is extremely good.

In order to ensure the effective starting of the centering device in the well, the N-stage supporting piston of the centering device of the design has a bottom rupture ring, and the rupture ring has different rupture pressures, the purpose is to ensure the sequential starting of the supporting piston, when the pressure inside the pipe is constant, due to the support The area of the bottom of the piston is different, so that the Nth stage support piston is started first, then the N-1th stage, and finally the first stage support piston is started to ensure the centering effect of the centering device in the well.

(2) The support can be locked in different well eyes to make the casing reliable centered

In the horizontal well large displacement well, the defects of the existing centering device are more and more obvious, mainly indicating that the resetting force is not guaranteed, the starting force is high, the friction coefficient with the well wall is large, and the rotation of the column is not satisfied, and the research and development is Because the centering device is open after the downhole, it completely avoids the friction with the well wall, meets the rotation requirement of the pipe string before the centering, and is also convenient to use for the irregular wellbore, and the starting pressure is low, when the pressure in the casing is low. It can be opened in the state of 1500-2000 psi. Once the C-shaped positioning self-locking ring is activated, the support bodies of each level can be locked. Each surface of the support body has a ratchet-shaped N-level positioning card slot, which can fix the support piston. A certain position, and a high supporting force, can also be effectively centered in the irregular well hole to ensure the centering of the casing in the wellbore. The N-stage sealing ring can effectively seal the supporting piston to support the centering device. The piston can withstand a pressure of >10000 psi without leakage, and the effect is quite obvious after actual use on site.

3. The arc-shaped support cap ensures a large supporting force and reduces the damage to the well wall.

Whether it is a flexible or rigid centering device, the contact point of the support point with the well wall is line contact or point contact. In order to ensure a certain supporting force, the unit pressure of the supporting point is larger, which causes damage to the well wall. The curved supporting cap used in this design can effectively fit the well wall and change the line or point contact. The surface contact of the circular arc effectively reduces the unit pressure of the support point, and ensures a high supporting force, which has little influence on the damage of the well wall, completely avoids the defects of the existing device, and is extremely reliable and practical.

DRAWINGS

1 is a schematic view showing the external structure of a downhole self-locking sleeve centering device provided by the present invention;

2 is a schematic structural view of the centering support portion before opening according to the present invention;

3 is a schematic structural view of the centering support portion after opening in the present invention;

Figure 4 is a partially enlarged schematic view of a portion A of Figure 3.

detailed description

In order to make the present invention more apparent, the preferred embodiments are described in detail with reference to the accompanying drawings.

As shown in FIG. 1 , the present invention provides a downhole self-locking sleeve centering device, which comprises a connecting portion 1 and a connecting portion 2 at two ends, and is disposed between the connecting portion 1 and the connecting portion 2 The centering support portion 3, the connecting portion 1 and the connecting portion 2 are both threaded structures connected to the sleeve, wherein the connecting portion 1 The LTC PIN thread is used, while the joint 2 is made of LTC BOX thread.

The invention adopts a threaded connection form to be coupled with the sleeve, instead of the joint hoop and functioning as a joint hoop, which is characterized in that the elastic centering device is prevented from being able to control the centering device in the downhole due to being placed outside the tubular string. The problem of the position avoids the problem that the rigidity of the rigid centering device increases the rigidity of the pipe string and causes the casing to be difficult. At the same time, due to the replacement of the hoop, the production cost is saved, the centering position is relatively fixed, and the operation of the casing is convenient and reliable, and the size of the coupling sleeve is 41/2" to 51/2".

2 to 4, the centering support portion 3 comprises a hollow coupling body 5, and in the circumferential direction of the coupling body 5 are three N-stage piston type self-locking support devices which are stepped out under pressure, N≥2 Hereinafter, the present invention will be further described by taking N=3 as an example.

Each of the three-stage piston type self-locking support devices includes a support body casing 4-1 fixed to the coupling body 5 and a three-stage support body composed of the first-stage support body 4-2 to the third-stage support body 4-4. The coupling body 5 is provided with opening orifices 4-10 communicating with the support body casing 4-1 and the third-stage support body, and the liquid pressure is introduced into the support body casings 4-1 and 3 by the opening orifices 4-10. After the stage supports the body, the level 3 support body is extended step by step under the action of pressure, and after all the three level 3 support bodies are extended into position, the sleeve position is centrally fixedly supported in the wellbore. The first-stage support body 4-2 is nested in and slidably fitted in the support body casing 4-1, and the second-stage support body 4-3 is nested in the first-stage support body 4-2 and slidably fitted thereto, and the third The stage support 4-4 is nested within the second stage support 4-3 and slidably mated therewith. Between the first stage support body 4-2 and the support body casing 4-1, between the second stage support body 4-3 and the first stage support body 4-2, and the third stage support body 4-4 and the second stage A first stage seal ring 4-9-1, a second stage seal ring 4-9-2 and a third stage seal ring 4-9-3 are respectively disposed between the support bodies 4-3. A first-stage rupture ring 4-6-1 and a second-stage rupture ring 4 are respectively disposed at the bottoms of the first-stage support body 4-2, the second-stage support body 4-3, and the third-stage support body 4-4. 6-2 and the third stage rupture ring 4-6-3, the first stage rupture ring 4-6-1 has an interference fit with the inner wall of the support body casing 4-1, and the second stage rupture ring 4-6-2 The inner wall of the primary rupture ring 4-6-1 has an interference fit, and the third-stage rupture ring 4-6-3 is interference-fitted with the inner wall of the second-stage rupture ring 4-6-2.

The invention uniformly distributes three 3-stage piston type self-locking support devices on the circumference, each device is provided with a three-stage support body capable of three-stage extension, and the first-stage support body of the third-stage support body is 4-2. The secondary support 4-3 and the third support 4-4 have different starting forces due to different cross-sectional areas. When a constant pressure (psi) value is maintained in the casing, the third-stage support 4-4 is first activated. After the position, the second stage support 4-3 is activated, and the first stage support 4-2 is activated after the same movement. In order to ensure the starting sequence of the third-stage support body, the bottom of the first-stage support body 4-2, the second-stage support body 4-3, and the third-stage support body 4-4 are respectively installed. a primary rupture ring 4-6-1, a second-stage rupture ring 4-6-2, and a third-stage rupture ring 4-6-3, the rupture ring having different rupture initiation pressures, and the successive rupture order is the third The stage rupture ring 4-6-3, the second stage rupture ring 4-6-2, the first stage rupture ring 4-6-1, the starting pressure of each level is a multiple of the previous stage, P2=2P3, P1=2P2 ( P3, P2, and P1 are the starting pressure values of the third-stage rupture ring 4-6-3, the second-stage rupture ring 4-6-2, and the first-stage rupture ring 4-6-1, respectively, when the pressure in the casing When the difference reaches 1000 to 2000 psi, it can be started. The advantage of this three-level support device is that the starting pressure is low, the minimum reset force at start-up is >3000N, and after each stage is started, each stage will generate a corresponding resetting force, all three stages are started, and the maximum resetting force will be far away. Out of the weight of the column, the centering performance is extremely reliable.

The present invention is provided with three first-stage ratchet shapes arranged from top to bottom on the outer circumferential surfaces of the first-stage support body 4-2, the second-stage support body 4-3 and the third-stage support body 4-4, respectively. The positioning groove 4-7-1, the second-stage ratchet-shaped positioning groove 4-7-2, and the third-stage ratchet-shaped positioning groove 4-7-3. A first-stage C-shaped self-locking ring 4-8-1 and a second-stage C are respectively disposed on the inner walls of the support body casing 4-1, the first-stage support body 4-2 and the second-stage support body 4-3. Shape positioning self-locking ring 4-8-2 and third-stage C-shaped positioning self-locking ring 4-8-3, first-stage C-shaped positioning self-locking ring 4-8-1, second-stage C-shaped positioning self-locking ring 4-8-2 and third-stage C-shaped positioning self-locking ring 4-8-3 and first-stage ratchet-shaped positioning groove 4-7-1, second-stage ratchet-shaped positioning groove 4-7-2 and The third-stage ratchet-shaped positioning grooves 4-7-3 are matched.

When the first stage support 4-2, the second stage support 4-3 and the third stage support 4-4 are activated, the first stage support 4-2, the second stage support 4-3 and the third stage The first-stage ratchet-shaped positioning groove 4-7-1 on the surface of the stage support 4-4, the second-stage ratchet-shaped positioning groove 4-7-2, and the third-stage ratchet-shaped positioning groove 4-7-3 A lock is generated with the first-stage C-shaped positioning self-locking ring 4-8-1, the second-stage C-shaped positioning self-locking ring 4-8-2, and the third-stage C-shaped positioning self-locking ring 4-8-3. The first stage support body 4-2, the second stage support body 4-3 and the third stage support body 4-4 have three first-stage ratchet-shaped positioning grooves 4-7-1 and a second-stage ratchet shape on the surface. The positioning groove 4-7-2 and the third-stage ratchet-shaped positioning groove 4-7-3 enable the first-stage support body 4-2, the second-stage support body 4-3, and the third-stage support body 4-4 Fixed in any extended position, it can be applied to different wells. Since the positioning is self-locking, when the first-stage support body 4-2, the second-stage support body 4-3, and the third-stage support body 4-4 are self-locking, the restoring force generated is constant, and It does not change with the action of external force. The maximum resetting force is the first-stage C-shaped positioning self-locking ring 4-8-1, the second-stage C-shaped positioning self-locking ring 4-8-2 and the third-level C-shaped positioning. The shear strength of the self-locking ring 4-8-3 is determined to be much higher than the weight of the pipe string. This type of construction is not available in existing centering devices.

A support portion 4-5 for contacting the well wall support is provided at an end of each of the third-stage support bodies 4-4, and the portion of the support portion 4-5 that is in contact with the well wall support is a semi-circular arc support contact cap 4 -5-1.

When the restoring force is large, the contact area of the support point of the centering device with the well wall is the key to whether the column can be accurately centered. When the contact area is too small, the unit of the support point is subjected to a large force, which will destroy the well wall and not be able to center the column well. When the area of the support point is large, the support force per unit area is small, Effectively support the centering of the column and reduce damage to the well wall. The invention adopts a semi-circular arc support cap type support contact mode, and the support is transformed from a point contact to a surface contact, thereby effectively reducing the unit force of the well wall, and the centering strength of the support of the column is constant, and the effective reduction is effectively reduced. Damage to the support of the borehole wall ensures a centered effect of the casing in the wellbore.

In order to facilitate the casing string downhole, the centering device provided by the present invention adopts a downhole pressure opening type. After the casing reaches the designated position downhole, the pressure in the casing controls the opening of the support body to center the casing. The support method will not damage the borehole wall, but also adapt to different wellbores, reduce the requirements on the wellbore, and the application range is greatly expanded.

The centering device of the invention is obviously used in the horizontal test well, the effect of the casing in the wellbore is quite accurate, the replacement efficiency of the cementing cement is high, and the cementing quality is stable, which is highly praised by users. It is now being promoted for use.

Claims

A downhole self-locking sleeve centering device comprises a connecting portion (1) and a connecting portion 2 (2) at two ends, and a centering support is provided between the connecting portion (1) and the connecting portion 2 (2) Part (3), characterized in that the centering support portion (3) comprises a hollow coupling body (5), and at least three of the circumferential direction of the coupling body (5) are stretched step by step under pressure N-stage piston type self-locking support device, N≥2;

Each N-stage piston type self-locking support device comprises a support body shell (4-1) fixed on the coupling body (5) and an N-stage support body composed of a first-stage support body and an N-th stage support body, first The stage support body is slidably engaged with the support body shell (4-1), and the N-stage support body is sequentially slidably fitted to the adjacent two stages of the first-stage support body, so that the N-stage support body can be pressed under pressure from the N-th stage support body. Extending stepwise, a support portion (4-5) for contacting the well wall support is provided on an end of the Nth support body away from the support body casing (4-1), and the support body at the first stage is The bottom of the Nth-stage support body is formed with a rupture ring, and the starting pressure of the first-stage support body to the N-th stage support body is gradually changed from large to small through the rupture ring.
A downhole self-locking sleeve centering device according to claim 1, wherein a first-stage support body of each of said N-stage piston type self-locking support devices is nested in said support body casing ( 4-1), the Nth support is sequentially nested adjacent to the first stage support, wherein the kth support is nested in the k-1th support, k=2,...,N .
A downhole self-locking sleeve centering device according to claim 2, wherein said rupture ring on the current support body is interference-fitted with the inner wall of the adjacent support body, on the first-stage support body The rupture ring is in an interference fit with the inner wall of the support body casing (4-1).
A downhole opening self-locking sleeve centering device according to claim 2, wherein in each of said N-stage piston type self-locking support means, on an outer circumferential surface of said Nth-stage support body At least one N-th stage ratchet-shaped positioning groove is provided, and at least one ratchet-shaped positioning groove is respectively arranged on the outer circumferential surface of the N-1th support body to the first-stage support body, and the N-1th support body is provided The inner wall of the first-stage support body is respectively provided with a C-shaped positioning self-locking ring, wherein the outer circumferential surface of the j-th stage support body is provided with at least one j-stage ratchet-shaped positioning groove, and a wall is provided on the inner wall thereof. J+1 level C-shaped positioning self-locking ring, j=1,...,N-1, the Nth-level ratchet-shaped positioning groove cooperates with the N-1th-order C-shaped positioning self-locking ring, the j-th order ratchet shape The positioning groove cooperates with the j-th C-shaped positioning self-locking ring, and the first-stage positioning self-locking ring is disposed on the inner wall of the support body casing (4-1).
A downhole self-locking sleeve centering device according to claim 2, wherein in each of said N-stage piston type self-locking support devices, adjacent two support bodies and a first-stage support body It is sealed with the support body casing (4-1) by a seal ring.
A downhole self-locking sleeve centering device according to claim 1, wherein said connecting portion (1) and said connecting portion (2) each adopt a threaded structure connected to the sleeve.
A downhole self-locking sleeve centering device according to claim 1, wherein the portion of the support portion (4-5) that is in contact with the well wall support is a semi-circular support contact cap (4-5). -1).