A liner head lost circulation well secondary completion pipe string and completion method

Abstract

The present application relates to a kind of tail pipe head leakage well secondary completion method, it is applied to the petroleum and natural gas drilling completion and workover field.It is composed of expansion cone, expansion hanger, sealing suspension element, expansion cone support shaft, fishable sealing plug, outlet anti-falling device, center tube and tail pipe sealing back insertion joint etc.Puts system to the predetermined position and inserts tail pipe sealing back insertion joint into original well hanger back connection cylinder, makes expansion cone in expansion hanger along center tube axial sliding by using hydraulic or hydraulic and mechanical combination, makes the permanent plastic deformation of expansion hanger body in radial, rubber element on expansion hanger is compressed in expansion hanger body and outer casing annulus, to achieve the purpose of sitting and sealing lower part of wellbore.Its technical advantage is that it can be not cemented to realize secondary sealing to the top of old well tail pipe, structure, simple process, reliable sealing, low cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil and gas, in particular to a tailpipe head leakage well secondary completion pipe string and completion method. BACKGROUND

[0002] With the continuous development and utilization of oil and natural gas resources, in order to improve the recovery rate and save development costs, deep wells, ultra-deep wells, horizontal wells and branch wells are gradually increasing, and tailpipe cementing technology is increasingly widely used.

[0003] Compared with full downhole casing cementing, tailpipe cementing has great advantages, mainly in:

[0004] (1) A large amount of casing and cement can be saved, the operation cycle can be reduced, and the construction cost can be reduced;

[0005] (2) Reduce the load of the drill string casing, reduce the construction pressure, and be beneficial to protect the oil and gas layer, especially the formation with low fracture pressure;

[0006] (3) It is beneficial to solve the technical problems that cannot be solved by ordinary cementing methods in deep wells, ultra-deep wells, small gap wells and other complex wells.

[0007] Due to the great advantages of tailpipe cementing, tailpipe cementing technology is increasingly widely used, but the tailpipe top sealing problem, especially the tailpipe top leakage in the later production process, restricts the development of tailpipe cementing technology. The expansion casing technology is one of the key technologies in the 21st century oil and gas industry. Several application fields of this technology have been put into industrial implementation abroad, and good economic benefits have been achieved, showing strong development momentum. The method of using expansion hanger to realize tailpipe top leakage sealing without cementing can realize secondary sealing of tailpipe top in old wells without cementing, and has the advantages of simple structure, reliable sealing and low cost. SUMMARY

[0008] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a tailpipe head leakage well secondary completion pipe string.

[0009] The technical scheme is as follows:

[0010] A tailpipe head leakage well secondary completion pipe string, comprising a running tool, the lower end of the running tool being sequentially connected with an expansion hanger, a tailpipe string and a sealing plug;

[0011] A plurality of annular sealing rings are sleeved on the outer wall of the sealing plug;

[0012] A plurality of sealing rubber elements are sleeved on the outer wall of the expansion hanger.

[0013] Further, the expansion hanger comprises:

[0014] The waist part is provided with a double male variable buckle expansion hanger cylinder;

[0015] Expansion cone sleeved between the lower end of the running-in tool and the expansion hanger cylinder;

[0016] Conical bearing shaft arranged below the expansion cone;

[0017] Blind plate recovery nipple fixed below the conical bearing shaft, which is communicated with the running-in tool;

[0018] Recoverable blind plate sleeved between the blind plate recovery nipple and the expansion hanger cylinder;

[0019] Impact pressure ball seat fixedly sleeved at the lower end of the blind plate recovery nipple;

[0020] Pressure cavity is left between the expansion cone and the recoverable blind plate, and a pressure transmission hole is arranged on the blind plate recovery nipple and communicated with the pressure cavity.

[0021] Further, the recoverable blind plate is limited in the double male variable buckle and sealingly matched with the double male variable buckle.

[0022] Further, the shape of the upper end of the recoverable blind plate is matched with the shape of the variable diameter position of the lower end of the double male variable buckle, thereby forming a limiting cooperation.

[0023] Further, the shape of the expansion cone is matched with the shape of the variable diameter position of the upper end of the double male variable buckle.

[0024] Further, the expansion cone is sealingly matched with the outer wall of the lower end of the running-in tool and the inner wall of the expansion hanger cylinder.

[0025] Further, the recoverable blind plate is sealingly matched with the outer wall of the blind plate recovery nipple and the inner wall of the expansion hanger cylinder.

[0026] Still further, a method for secondary completion of a lost circulation well by using a liner hanger, comprising:

[0027] First, according to the field conditions, the downhole tool and the casing string are combined, and the casing string is combined from bottom to top as follows: sealing plug + casing string + expansion hanger + running-in tool;

[0028] Second, when the tool is lowered to the top of the original well liner hanger, the pump is started to flush the top of the liner, and then the sealing plug is inserted into the original well liner hanger return sleeve for lower sealing;

[0029] Third, the ball is thrown and pumped to the impact pressure ball seat to stop pressure, and the expansion hanger is seated and released to perform upper sealing;

[0030] Finally, all the inner tube tools are pulled out for completion.

[0031] Further, the sealing suspension elements on the expansion hanger and the sealing plug can be made of high-temperature-resistant rubber rings according to requirements.

[0032] Further, under the hydraulic and mechanical action, the expansion cone slides in the expansion suspension cylinder along the axial direction of the running-in drill tool when pressure is built up, so that the expansion suspension cylinder is permanently plastically deformed in the radial direction to complete the expansion hanger setting; after the expansion hanger is set, the inner diameter of the whole workover pipe string is not less than the inner diameter of the original well tail pipe.

[0033] The present application has the following advantages:

[0034] (1) The method for plugging the top leakage of the tail pipe without cementing by using the expansion hanger has simple structure and process and reliable sealing.

[0035] (2) The method for plugging the top leakage of the tail pipe without cementing by using the expansion hanger can omit the cementing link of the conventional tail pipe top leakage plugging, greatly reduces the construction period, saves the operation cost and reduces the construction risk.

[0036] (3) The method for plugging the top leakage of the tail pipe without cementing by using the expansion hanger can realize the tail pipe top leakage plugging without reducing the original well completion inner diameter.

[0037] (4) The expansion hanger has an independent sealing pressure chamber, so that the pressure ball seat is not additionally arranged, and the well completion plug operation link is omitted. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 A tail pipe leakage well secondary completion pipe string schematic view

[0039] Figure 2 A pipe string running-in schematic view

[0040] Figure 3 A sealing plug back-insertion sealing schematic view

[0041] Figure 4 A ball-throwing pressure building-up expansion hanger setting schematic view

[0042] Figure 5 An expansion hanger releasing and well completion schematic view

[0043] In the figure, 1 is an expansion hanger, 2 is a double male variable buckle, 3 is a tail pipe string, 4 is a sealing plug, 5 is an original well tail pipe hanger, 6 is an original well tail pipe, 7 is a cone bearing shaft, 8 is a pressure ball seat, 9 is an expansion cone, 10 is a recoverable blind plate, 11 is a running-in drill tool, 12 is a pressure building-up ball, 13 is a pressure transmission hole, and 14 is a blind plate recovery short joint. DETAILED DESCRIPTION

[0044] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0045] Example 1:

[0046] like Figure 1 As shown, a secondary completion string for a lost liner well may include an inner string and an outer string. The inner string comprises a running drill tool 11, an expansion cone 9, an expansion cone support shaft 7, a retrievable blind plate 10, and a pressure ball seat 8. The outer string comprises an expandable hanger 1, a double male buckle 2, a casing string 3, and a sealing plug. In the inner string, a pressure hole 13 is provided on the blind plate recovery sub 14 between the upper portion of the retrievable blind plate 10 and the lower portion of the expansion cone 9. The retrievable blind plate 10 is restrained downward by the double male buckle 2 and forms a sliding seal with its inner wall, thereby, together with the expansion cone 9, providing a pressure chamber for expansion of the expandable hanger 1. After completion, when the running drill tool 11 is removed, the pressure ball seat 8 restrains the retrievable blind plate 10 downward, enabling its recovery. In the tool string, the inner diameter of the expandable hanger 1 after operation is significantly larger than the inner diameter of the original well liner 6, while the inner diameters of the casing string 3 and the sealing plug 4 are no smaller than the inner diameter of the original well liner 6.

[0047] like Figures 1 to 5 As shown, a secondary completion string for a lost liner well comprises the following steps: running a sealing plug 4, a casing string 3, and an expansion hanger 1 tool assembly; flushing the top of the original well liner and connecting back the sealing plug 4; hanging the expansion hanger 1; and pulling out and running the drilling tool 11 to complete subsequent operations.

[0048] like Figure 2 The figure shows the process of running the tool assembly. When the tool assembly reaches the top of the liner hanger 5 of the original well, the pump is turned on for flushing.

[0049] like Figure 3 As shown, the sealing plug 4 is tied back in, and the tool assembly is inserted into the tie-back barrel of the original well liner hanger 5 under pressure to achieve the next step of sealing.

[0050] like Figure 4 As shown, the process of dropping the ball to hold the pressure, expand and hang the expansion hanger 1 is as follows: after the tool assembly is in place, the pressure-holding ball 12 is put into the pressure ball seat 8 for impact pressure, and the pressure acts on the expansion cone 9 through the pressure transmission hole 13, pushing the expansion cone 9 to move upward in the axial direction, causing the expansion hanger 1 to undergo plastic deformation in the radial direction, squeezing its outer wall rubber ring to the inner wall of the original well technical casing to achieve sealing and suspension.

[0051] like Figure 5The figure shows the well completion after the inflation hanger 1 is set and released, the running-in tool 11 and all inflation tools are lifted out. The inner diameter of the well completion after the operation is not less than the inner diameter of the original well liner 6, realizing zero loss of inner diameter.

[0052] Example two:

[0053] A method for plugging the top leakage of the liner by using the inflation hanger without cementing the well, which consists of the following steps: the lower liner string 3, the sealing plug 4, the inflation hanger setting and the lifting of the inner pipe tool.

[0054] Firstly, according to the field conditions, the well tool and the liner string 3 are combined from bottom to top: the sealing plug 4 + the liner string 3 + the inflation hanger 1 + the running-in tool 11.

[0055] Secondly, when the tool is lowered to the top of the original well liner hanger, the sealing plug 4 is inserted into the original well liner hanger return connection cylinder after the pump is opened to flush the top of the liner, realizing the lower sealing.

[0056] Thirdly, the ball is thrown and pumped to the pressure holding ball seat 8 to hold pressure, realizing the setting and releasing of the inflation hanger 1, and realizing the upper sealing.

[0057] Finally, the entire inner pipe tool is lifted out for well completion.

[0058] The sealing suspension elements on the inflation hanger 1 and the sealing plug 4 can select high-temperature-resistant rubber rings according to the needs, which are tightly combined with the inner wall of the outer casing and the original well liner hanger 5 return connection cylinder respectively after the completion of the construction, having complete hydraulic sealing performance and reliable suspension performance.

[0059] The inflation hanger 1 is provided with a recyclable blind plate 10, which can provide a reliable pressure chamber during the construction of the inflation hanger 1, and can be lifted out of the wellbore with the running-in tool 11 after the completion of the construction, realizing the recovery of the wellbore without drilling. Under the action of hydraulic and mechanical methods, the inflation cone 9 slides axially along the running-in central pipe in the body of the inflation hanger 1, causing permanent plastic deformation of the body of the inflation hanger 1 in the radial direction to realize the setting of the inflation hanger 1. After the inflation hanger 1 is set, the inner diameter of the entire workover pipe string is not less than the inner diameter of the original well liner, realizing zero loss of the inner diameter of the wellbore.

[0060] During the operation, the running depth can be accurately controlled, and the length of the liner string 3 can be designed according to the technical casing above the top of the original well liner, which can also reinforce and repair the original well technical casing.

[0061] Example three:

[0062] As Figures 1 to 5As shown, a method for plugging a top leakage of a liner by using an expansion hanger without cementing well is composed of the following steps: a tool combination of a sealing plug 4, a liner string 3 and an expansion hanger 1 is lowered, the top of the original well liner is flushed, the sealing plug 4 is connected, the expansion hanger 1 is set, the running-in tool 11 is pulled out, and subsequent operations are completed.

[0063] As shown, Figure 1 The inner pipe string combination is composed of the running-in tool 11, the expansion cone 9, the expansion cone bearing shaft 7, the recoverable blind plate 10 and the pressure ball seat 8. The outer pipe string combination is composed of the expansion hanger 1, the double male variable buckle 2, the liner string 3 and the sealing plug. The pressure transmission hole 13 is arranged on the blind plate recovery nipple 14 between the upper part of the recoverable blind plate 10 and the lower part of the expansion cone 9 in the inner pipe string combination. The recoverable blind plate 10 is limited downward by the double male variable buckle 2 and is in sliding sealing with the inner wall of the double male variable buckle 2, so as to provide a pressure cavity for the expansion of the expansion hanger 1 together with the expansion cone 9. When the running-in tool 11 is pulled out at the end of the construction, the pressure ball seat 8 limits the recoverable blind plate 10 downward to realize the recovery of the recoverable blind plate 10. The inner diameter of the expansion hanger 1 after the operation of the tool string combination is much larger than the inner diameter of the original well liner 6, and the inner diameters of the liner string 3 and the sealing plug 4 are not less than the inner diameter of the original well liner 6.

[0064] As shown, Figure 2 It is the tool combination lowering process. After the tool combination is lowered to the top of the original well liner hanger 5, the pump is started to flush.

[0065] As shown, Figure 3 It is the sealing plug 4 connection process. The tool combination is inserted into the connection cylinder of the original well liner hanger 5 to realize the next sealing.

[0066] As shown, Figure 4 It is the process of throwing the ball to expand and set the expansion hanger 1. After the tool combination is in place, the pressure ball 12 is thrown to the pressure ball seat 8 to pressurize, the pressure acts on the expansion cone 9 through the pressure transmission hole 13 to push the expansion cone 9 to move upward in the axial direction, so that the expansion hanger 1 is plastically deformed in the radial direction to press the outer wall rubber ring of the expansion hanger 1 to the inner wall of the original well liner to realize sealing and suspension.

[0067] As shown, Figure 5 It is the well completion diagram after the expansion hanger 1 is set and released and the running-in tool 11 and all expansion tools are pulled out. The inner diameter of the well completion after the operation is not less than the inner diameter of the original well liner 6 to realize zero loss of the inner diameter.

[0068] The method for plugging a top leakage of a liner by using an expansion hanger without cementing well can effectively reduce the operation risk, increase the safety of personnel and equipment, greatly save the operation time, and can be widely used in the fields of remedial operations for top leakage of a liner.

[0069] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described.

Claims

1. A tailpipe head lost circulation secondary completion pipe string comprising a running tool, a primary well tailpipe, characterized in that, The lower end of the running-in tool is sequentially connected with an expansion hanger, a tailpipe string and a sealing plug; a plurality of annular sealing rings are sleeved on the outer wall of the sealing plug; a plurality of sealing rubber elements are sleeved on the outer wall of the expansion hanger; the expansion hanger comprises: an expansion hanger cylinder provided with a double-male variable buckle at the waist; an expansion cone sleeved between the lower end of the running-in tool and the expansion hanger cylinder; a cone supporting shaft arranged below the expansion cone; a blind plate recovery nipple fixedly connected below the cone supporting shaft, the blind plate recovery nipple being communicated with the running-in tool; a recoverable blind plate sleeved between the blind plate recovery nipple and the expansion hanger cylinder; a bump ball seat fixedly sleeved at the lower end of the blind plate recovery nipple; a pressure cavity is left between the expansion cone and the recoverable blind plate, a pressure transmission hole is formed on the blind plate recovery nipple and communicated with the pressure cavity; the outer shape of the expansion cone is matched with the outer shape of the variable diameter position at the upper end of the double-male variable buckle; the expansion cone is in interference sealing fit with the outer wall of the lower end of the running-in tool and the inner wall of the expansion hanger cylinder.

2. A liner head loss circulation well secondary completion pipe string according to claim 1, characterized in that, The recoverable blind plate is limited in the double-male variable buckle and is in sealing fit with the double-male variable buckle.

3. A liner head loss circulation well secondary completion pipe string according to claim 2, characterised in that, The outer shape of the upper end of the recoverable blind plate is matched with the outer shape of the variable diameter position at the lower end of the double-male variable buckle to form a limiting fit.

4. The liner head loss circulation well secondary completion pipe string of claim 2, wherein, The recoverable blind plate is in interference sealing fit with the outer wall of the blind plate recovery nipple and the inner wall of the expansion hanger cylinder.

5. A method for the secondary completion of a lost circulation well with a liner head, using a secondary completion string for the secondary completion of a lost circulation well with a liner head according to any one of claims 1 to 4, characterized in that, The method comprises the following steps: first, according to the field conditions, the downhole tool and the casing string are combined from bottom to top as follows: sealing plug + casing string + expansion hanger + running-in tool; second, when the tool reaches the top of the original well tailpipe hanger, the pump is started to flush the top of the tailpipe, and then the sealing plug is inserted into the original well tailpipe hanger return coupling for lower sealing; third, the ball is thrown and pumped to the bump ball seat to hold pressure, the expansion hanger is hung and released to perform upper sealing; finally, the entire inner pipe tool is pulled out for well completion.

6. The method of claim 5, wherein, The sealing suspension elements on the expansion hanger and the sealing plug are selected according to the requirement of high-temperature-resistant rubber ring.

7. The method of claim 6, wherein, When holding pressure, the expansion cone slides in the expansion hanger cylinder along the axis of the running-in tool under the action of hydraulic pressure and mechanical mode, so that the expansion hanger cylinder is permanently plastically deformed in the radial direction to complete the expansion hanger hanging; after the expansion hanger is hung, the inner diameter of the entire workover pipe string is not less than the inner diameter of the original well tailpipe.

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