Cement-free segmented packing well cementation device and method for continental facies shale oil horizontal well

Abstract

The invention relates to the technical field of drilling engineering, in particular to a continental facies shale oil horizontal well cement-free subsection packing well cementation device and a continental facies shale oil horizontal well cement-free subsection packing well cementation method. The device comprises a production casing pipe, the production casing pipe comprises a first casing pipe and a second casing pipe, the first casing pipe is connected with the second casing pipe, the first casing pipe is provided with a plurality of well cementation tools, the second casing pipe is provided with a plurality of well completion mechanisms, the well completion mechanism at the tail end is connected with a float collar, and the float collar is connected with a float shoe. The well completion mechanism comprises well cementation tools and a fracturing tool, and the well cementation tools are detachably connected to the two sides of the fracturing tool respectively. According to the cement-free segmented packing well cementation device and method for the continental facies shale oil horizontal well, a conventional cement well cementation and fracturing perforation process is replaced by a segmented packing well cementation technology and a fracturing channel self-opening technology, the well cementation quality is improved, the fracturing efficiency of well cementation can be improved, the production increasing operation time is effectively shortened, and the production cost is reduced. And the cost investment is further reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of drilling engineering, and in particular to a cement-free segmented isolation cementing device and method for a continental shale oil horizontal well. Background Art

[0002] The existing cementing technology for continental shale oil horizontal wells requires the injection of cement slurry, replacement of drilling fluid, casing pressure testing and other process steps after the casing is lowered. Since shale oil extraction requires the transformation of the reservoir, perforation and fracturing operations must be carried out in the later stage.

[0003] Conventional cementing of continental shale oil horizontal wells mainly has the following technical difficulties: First, the long horizontal section and poor well wall stability make it difficult to safely lower and center the casing during cementing operations, the cement slurry performance requirements are high, and the oil-based drilling fluid displacement is difficult. Second, shale oil is deeply buried, the formation pressure is high, the formation temperature is high, and the pressure system is complex. During cementing operations, the compatibility of conventional pre-fluid and oil-based drilling fluid is poor, and it is easy to thicken in advance, resulting in the inability to perform normal cementing operations. Third, the cement slurry displacement efficiency is low. During cementing, the casing is affected by gravity, the centering is poor, and it is easy to be eccentric, or even stick to the lower well wall, resulting in a decrease in the cement slurry displacement efficiency in the narrow gap of the annulus, making it difficult to remove drilling fluid and cuttings, affecting the cementing quality of the horizontal section. Fourth, during the later production increase operation, it is difficult to open the fracturing sleeve under the cement sealing condition, which affects the operation efficiency. Therefore, a cement-free segmented isolation cementing device and method for continental shale oil horizontal wells are proposed. Summary of the invention

[0004] 1. Technical issues to be resolved The present invention provides a cement-free segmented isolation cementing device and method for continental shale oil horizontal wells, which avoids the defects of the existing methods due to the use of conventional cement cementing technology, such as poor wellbore sealing integrity after cementing, the need for perforating during later fracturing, and difficulty or failure in opening the fracturing sleeve under cement sealing conditions.

[0005] (II) Technical solution In order to solve the above problems, the present invention provides a cement-free segmented isolation cementing device for continental shale oil horizontal wells, comprising: A production casing, the production casing comprising a first casing and a second casing, the first casing being connected to the second casing, a plurality of cementing tools being installed on the first casing, a plurality of completion mechanisms being installed on the second casing, the completion mechanism at the tail end being connected to a float collar, and the float collar being connected to a float shoe; The completion mechanism comprises a cementing tool and a fracturing tool, and the two sides of the fracturing tool are detachably connected to the cementing tool.

[0006] Preferably, the length of the first casing is adapted to the well depth of the well, and the length of the second casing is determined according to the length of the reservoir fracturing transformation of the well.

[0007] Preferably, the length of the first casing determines the number of fixtures installed therein, and the length of the second casing determines the number of completion mechanisms installed therein.

[0008] Preferably, the fracturing tool is provided with at least one inner tapered hole, one side of the inner tapered hole is connected to a straightening pipe, and the straightening pipe is connected to a cementing device through threads.

[0009] Preferably, the cementing tool comprises an expansion cylinder, both sides of the expansion cylinder are connected to a central tube, the expansion cylinder and the central tube are sealed by an expansion ring, a hydraulic chamber is formed between the expansion cylinder and the central tube, and the central tube is connected to a straightening tube.

[0010] Preferably, a cast-in layer is provided inside the inner tapered hole, and the cast-in layer is soluble.

[0011] Preferably, the expansion ring is connected to a one-way liquid inlet valve, and the one-way liquid inlet valve controls the pressure of the inlet liquid.

[0012] Preferably, the expansion cylinder comprises an expansion tube, the outer side of the expansion tube is wrapped with a first rubber layer, and the inner side of the expansion tube is a second rubber layer.

[0013] The present invention also provides a method for cementing a terrestrial shale oil horizontal well without cement segmented isolation, comprising: Step S1: Select production casing according to drilling specifications and configure cementing equipment; Step S2: preset the working pressure of the cementing tool, preset the working time of the fracturing tool, and lower the configured cementing device to a designated position in the well; Step S3: When the cementing device reaches the predetermined position, the cementing plug is sent from the wellhead to the floating collar by the drilling pump, and the pressure is held up to a preset pressure, and all cementing tools are started in sequence, starting with the cementing tool closest to the floating collar; Step S4: After completing step S3, both the inner and outer sides of the fracturing tool are filled with drilling fluid. Under the conditions of the drilling fluid, the temperature in the well and the preset pressure, the cast layer dissolves within the preset time, and a fracturing channel is formed on the second casing, laying the foundation for subsequent production increase operations.

[0014] (III) Beneficial effects The device and method for cementing continental shale oil horizontal wells without cement segmented isolation provided by the present invention replace conventional cement cementing and fracturing perforation processes through segmented isolation cementing technology and fracturing channel self-opening technology, which can not only improve the cementing quality, but also improve the fracturing efficiency of cementing, effectively shorten the production increase operation time, and further reduce cost investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic structural diagram of a cement-free segmented isolation cementing device for continental shale oil horizontal wells according to an embodiment of the present invention; Figure 2 It is a structural schematic diagram of a cementing tool according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a fracturing tool according to an embodiment of the present invention; Figure 4 It is a schematic structural diagram of an expansion cylinder according to an embodiment of the present invention.

[0016] Among them: 1- cementing tool; 2- fracturing tool; 3- production casing; 4- floating collar; 5- floating shoe; 6- expansion ring; 7- expansion cylinder; 8- one-way liquid inlet valve; 9- center pipe; 10- straightening pipe; 11- inner cone hole; 12- first rubber layer; 13- expansion pipe; 14- second rubber layer. Implementation

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Figure 1 FIG. 1 is a schematic diagram of the structure of a cement-free segmented isolation cementing device for a continental shale oil horizontal well according to an embodiment of the present invention. Figure 1 As shown, the present invention provides a cement-free segmented isolation cementing device for continental shale oil horizontal wells, comprising: The production casing 3 comprises a first casing and a second casing, wherein the first casing is connected to the second casing, a plurality of cementing tools 1 are installed on the first casing, and a plurality of completion mechanisms are installed on the second casing, wherein the completion mechanism at the tail end is connected to a float collar 4, and the float collar 4 is connected to a float shoe 5.

[0019] In the cementing device, a plurality of cementing tools 1 are installed on the first casing, and the number of the fixing tools 1 installed thereon is determined according to the length of the first casing, the spacing between the two fixing tools 1 is 150-200 mm, the length of the first casing is adapted to the well depth of drilling, the tail end of the first casing is connected to the second casing, and a plurality of completion mechanisms are installed on the second casing, in the completion mechanism, the distance between the fixing tool 1 and the fracturing tool 2 is 50-100 mm, the distance between the two completion mechanisms is 100-150 mm, the number of the completion mechanisms is determined according to the length of the second casing, and the length of the second casing is determined according to the reservoir fracturing transformation design of actual drilling.

[0020] In this cementing device, Figure 2 FIG. 1 is a schematic diagram of the structure of a cementing tool according to an embodiment of the present invention. Figure 2 As shown, the cementing tool 1 includes an expansion cylinder 7, both sides of which are connected to a central tube 9, the expansion cylinder 7 and the central tube 9 are sealed by an expansion ring 6, the expansion ring 6 is connected to a one-way liquid inlet valve 8, the one-way liquid inlet valve 8 controls the pressure of the inlet liquid, and a hydraulic chamber is provided between the expansion cylinder 7 and the central tube 9.

[0021] It should be noted that the expansion ring 6 is made of a strong ductile alloy, such as a magnesium alloy, a titanium alloy, and an aluminum alloy, which can effectively improve the sealing reliability of the end of the expansion tube 7 .

[0022] In practical applications, the one-way liquid inlet valve 8 is located in the seals at both ends of the expansion tube 7 and the central tube 9. The one-way liquid inlet valve 8 can be opened at the wellhead according to the set pressure, and liquid is filled into the expansion tube 7 to start the cementing tool 1 to expand and seal the annulus between the casing and the open hole wall. The upper and lower ends of the central tube 9 are threaded.

[0023] It should be noted that Figure 4 Schematic diagram of the structure of the expansion cylinder according to an embodiment of the present invention. Figure 4 As shown, the expansion cylinder 7 includes an expansion tube 13 , the outer side of the expansion tube 13 is wrapped with a first rubber layer 12 , and the inner side of the expansion tube 13 is a second rubber layer 14 .

[0024] In actual application, the expansion cylinder 7 is composed of three layers of materials, namely, high-strength rubber, metal expansion tube and water-swellable rubber, from the outside to the inside. The high-strength rubber is mostly vulcanized rubber, the metal expansion tube is mostly 304 stainless steel expansion tube, and the water-swellable rubber includes PN water-swellable waterstop strip, BW water-swellable waterstop strip, waterstop rubber strip and water-swellable rubber strip. The expansion cylinder 7 is sleeved on the outside of the central tube 9, and the two ends of the expansion cylinder 7 are sealed with the central tube 9 by the expansion ring 6, and a hydraulic cavity is formed between the expansion cylinder 7 and the central tube 9.

[0025] It should be noted that water-swelling rubber has more outstanding characteristics and advantages than ordinary rubber. This type of rubber expands and deforms 2-3 times when it comes into contact with water, and fills all irregular surfaces, holes and gaps in the joints, while generating huge contact pressure to completely prevent leakage. When the joints or construction joints are displaced, causing the gap to exceed the elastic range of the material, ordinary rubber water-stopping materials lose their water-stopping effect. This material can also stop water by absorbing water and swelling. Using water-swelling rubber as a leak-proof and sealing water-stopping material not only saves on usage, but also eliminates the characteristic of elastic fatigue caused by excessive compression of general elastic materials, making the waterproof effect more reliable.

[0026] In practical applications, the completion mechanism includes a cementing tool 1 and a fracturing tool 2, and both sides of the fracturing tool 2 are detachably connected to the cementing tool 1.

[0027] In this cementing device, Figure 3 FIG. 1 is a schematic diagram of the structure of a fracturing tool according to an embodiment of the present invention. Figure 3 As shown, the fracturing tool 2 includes a straightening tube 10 and an inner cone hole 11. The straightening tube 10 adopts an integrated elastic straightening structure. The interior of the inner cone hole 11 is provided with an inlay layer, which is soluble. The aperture, number of holes and distribution of the inner cone hole 11 are determined according to the fracturing design. In order to ensure the sealing performance of the pipe string under high pressure conditions, the dissolution period of the soluble substance cast in the inner cone hole 11 is controllable in the corresponding environment.

[0028] In practical applications, the fracturing tool 2 is provided with at least one inner tapered hole 11, the interior of the inner tapered hole 11 is provided with a cast-in layer which can be dissolved, one side of the inner tapered hole 11 is connected to a centralizing tube 10, and the centralizing tube 10 is connected to the center tube 9 through threads.

[0029] It should be noted that the soluble substances in the cast-in layer include aluminum alloy, magnesium alloy, zinc alloy and aluminum-magnesium alloy, etc. The dissolution period of the soluble substances in the drilling fluid medium of the wellbore environment is set by adjusting the material composition of the soluble substances. The inner cone hole 11 of the pressure tool 2 adopts an inner cone structure to improve its resistance to internal pressure, which is conducive to reliably starting the segmented isolation tool to implement cementing operations. At the same time, by connecting the fracturing tool 2 to the horizontal fracturing section casing, the fracturing tool 2 is provided with a plurality of inner cone holes 11. After the cast-in layer of the inner cone hole 11 is dissolved, an inner cone-type fracturing channel is formed. The fracturing channel has a nozzle effect. When replacing the fracturing sleeve or later perforating, it is beneficial to improve the efficiency of reservoir transformation and shorten the operation cycle.

[0030] In actual application, the completion mechanism at the tail end is connected to the float collar 4 and the float shoe 5 in sequence. The float collar 4 is mainly used to prevent backflow and form a pipe string sealing space with the cementing plug. The pressure in the pipe is increased by pumping drilling fluid to start the cementing tool 1. The float shoe 5 is mainly used to guide the lowering of the cementing device. A rotating head is designed at the end of the float shoe 5 to improve the passability of the cementing device when encountering obstacles.

[0031] In this cementing device, the cementing tool 1 can achieve high-quality and efficient horizontal well casing centering and annulus segmented isolation cementing by pre-setting segmented isolation tools in the horizontal section without cement. The fracturing tool 2 is mainly used to provide a fracturing channel and improve the casing centering degree. The inner cone hole 11 of the fracturing tool 2 is designed with a soluble cast layer, and the cast layer is dissolved at a set time, making the inner cone hole 11 completely transparent, so as to form channels inside and outside the pipe for later dragging fracturing in the casing, eliminating the conventional perforating process.

[0032] The cement-free segmented isolation cementing device for continental shale oil horizontal wells provided by the present invention performs cement-free segmented isolation of the horizontal well by means of a cementing tool, achieves casing centering and annulus isolation, improves the sealing quality and efficiency, and at the same time, uses a fracturing tool to replace the later perforating operation, improves the efficiency of oil layer transformation, and shortens the production increase operation cycle.

[0033] In practical applications, the existing technology is the cementing technology for continental shale oil horizontal wells. Due to the low cement slurry displacement efficiency and poor centrality of the horizontal section casing, the sealing integrity of the wellbore is poor after cementing, perforation is required during later fracturing, and the fracturing sleeve is difficult or fails to open under cement sealing conditions. These problems seriously affect the operation of the oil well and the production efficiency. Therefore, the present invention also provides a method based on a cement-free segmented isolation cementing device for continental shale oil horizontal wells, comprising: Step S1: Select production casing according to drilling specifications and configure cementing equipment; Step S2: preset the working pressure of the cementing tool, preset the working time of the fracturing tool, and lower the configured cementing device to a designated position in the well; Step S3: After the cementing device reaches the predetermined position, the cementing plug is sent from the wellhead to the floating collar by the drilling pump, and the pressure is held up to a preset pressure. All cementing tools are started in sequence, starting with the cementing tool closest to the floating collar; Step S4: After completing step S3, both the inner and outer sides of the fracturing tool are filled with drilling fluid. Under the conditions of the drilling fluid, the temperature in the well and the preset pressure, the cast layer dissolves within the preset time, and a fracturing channel is formed on the second casing, laying the foundation for subsequent production increase operations.

[0034] The following is a detailed description of the working principle of the application process of this cement-free segmented isolation cementing device for continental shale oil horizontal wells: First, a well is selected, and the lengths of the corresponding first casing and second casing are selected. The first casing and the second casing are connected to form a production casing 3. In this embodiment, the first casing in the well is connected to two cementing tools 1, and the two cementing tools 1 are spaced 200 mm apart. Two completion mechanisms are installed on the second casing, and the cementing tool 1 and the fracturing tool 2 are spaced 50 mm apart, and the two completion mechanisms are spaced 150 mm apart. The tail end completion mechanism is connected to the float collar 4 and the float shoe 5 in sequence.

[0035] It should be noted that, in actual applications, the three layers of the expansion tube 7 are made of vulcanized rubber, 304 stainless steel expansion tube and PN water-swellable waterstop strip, and the expansion rings 6 sealing the two sides of the expansion tube 7 are made of titanium alloy.

[0036] Then, the working pressure of the cementing tool 2 is set, and the working time of the fracturing tool 2 is set according to the material composition of the cast layer of the inner cone hole 11, and the connected cementing device is lowered to the designated position of the drilling, which is determined according to the actual specifications of the drilling.

[0037] It should be noted that, in this embodiment, the material of the cast-in layer of the inner tapered hole 11 is an aluminum-magnesium alloy.

[0038] Next, when the cementing device reaches the predetermined position, the cementing plug is sent from the wellhead of the well to the floating collar 4 through the drilling pump, the cementing tool 1 is pressurized to the set pressure, the one-way liquid inlet valve 8 is opened, the expansion cylinder 7 is filled with drilling fluid of a certain pressure, and all cementing tools 1 on the production casing 3 are opened in turn to seal the annular space between the casing and the well wall, thereby realizing cementless cementing.

[0039] Finally, under the conditions of drilling fluid medium, temperature in the well and preset pressure, the aluminum-magnesium alloy dissolves within the preset time, the inner cone hole 11 gradually becomes transparent, and an open fracturing channel is formed on the second casing. The fracturing pipeline has a nozzle effect, and the fracturing channel can carry out subsequent production increase operations, further laying the foundation for subsequent work processes.

[0040] The device and method for cementing continental shale oil horizontal wells without cement segmented isolation provided by the present invention replace conventional cement cementing and fracturing perforation processes through segmented isolation cementing technology and fracturing channel self-opening technology, which can not only improve the cementing quality, but also improve the fracturing efficiency of cementing, effectively shorten the production increase operation time, and further reduce cost investment.

[0041] The above implementation modes are only used to illustrate the present invention, but not to limit the present invention. Ordinary technicians in the relevant technical field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also belong to the scope of the present invention. The patent protection scope of the present invention should be defined by the claims.

Claims

1. A cementless segmented isolation cementing device for continental shale oil horizontal wells, characterized in that: include: A production casing (3), the production casing (3) comprising a first casing and a second casing, the first casing being connected to the second casing, a plurality of cementing tools (1) being installed on the first casing, a plurality of completion mechanisms being installed on the second casing, the completion mechanism at the tail end being connected to a float collar (4), and the float collar (4) being connected to a float shoe (5); The well completion mechanism comprises a cementing tool (1) and a fracturing tool (2), and two sides of the fracturing tool (2) are respectively detachably connected to the cementing tool (1).

2. The cement-free segmented isolation cementing device for continental shale oil horizontal wells according to claim 1 is characterized in that: The length of the first casing is adapted to the depth of the well being drilled, and the length of the second casing is determined according to the length of the reservoir fracturing transformation of the well being drilled.

3. The cement-free segmented isolation cementing device for continental shale oil horizontal wells according to claim 2 is characterized in that: The length of the first casing determines the number of fixing tools (1) installed therein, and the length of the second casing determines the number of completion mechanisms installed therein.

4. The cement-free segmented isolation cementing device for continental shale oil horizontal wells according to claim 1, characterized in that: The fracturing tool (2) is provided with at least one inner tapered hole (11), one side of the inner tapered hole (11) is connected to a centralizing pipe (10), and the centralizing pipe (10) is connected to a cementing tool (1) via threads.

5. The cement-free segmented isolation cementing device for continental shale oil horizontal wells according to claim 4 is characterized in that: The cementing tool (1) comprises an expansion cylinder (7), both sides of the expansion cylinder (7) are connected to a central tube (9), an expansion ring (6) is used to seal the expansion cylinder (7) and the central tube (9), a hydraulic chamber is formed between the expansion cylinder (7) and the central tube (9), and the central tube (9) is connected to a centralizing tube (10).

6. The cement-free segmented isolation cementing device for continental shale oil horizontal wells according to claim 4, characterized in that: A casting layer is provided inside the inner tapered hole (11), and the casting layer is soluble.

7. The cement-free segmented isolation cementing device for continental shale oil horizontal wells according to claim 5, characterized in that: The expansion ring (6) is connected to a one-way liquid inlet valve (8), and the one-way liquid inlet valve (8) controls the pressure of the inlet liquid.

8. The cement-free segmented isolation cementing device for continental shale oil horizontal wells according to claim 5, characterized in that: The expansion cylinder (7) comprises an expansion tube (13), the outer side of the expansion tube (13) is wrapped with a first rubber layer (12), and the inner side of the expansion tube (13) is a second rubber layer (14).

9. A method for cementing a continental shale oil horizontal well without cement segmented isolation device according to any one of claims 1 to 8, characterized in that: include: Step S1: Select production casing according to drilling specifications and configure cementing equipment; Step S2: preset the working pressure of the cementing tool, preset the working time of the fracturing tool, and lower the configured cementing device to a designated position in the well; Step S3: After the cementing device reaches the predetermined position, the cementing plug is sent from the wellhead to the floating collar by the drilling pump, and the pressure is held up to a preset pressure. All cementing tools are started in sequence, starting with the cementing tool closest to the floating collar; Step S4: After completing step S3, both the inner and outer sides of the fracturing tool are filled with drilling fluid. Under the conditions of the drilling fluid, the temperature in the well and the preset pressure, the cast layer dissolves within the preset time, and a fracturing channel is formed on the second casing, laying the foundation for subsequent production increase operations.

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