Casing drilling well cementation-free pipe column and construction method

Abstract

The invention provides a casing well drilling well cementation-free tubular column and a construction method, the casing well drilling well cementation-free tubular column comprises a casing string, a drill bit is arranged at the lower end of the casing string, and the casing string replaces a drill rod to drive the drill bit to drill; the self-expansion packers are arranged in the axial direction of the casing string at intervals, can expand in the environment of an expanding agent and are fixed in the stratum; wherein the casing pipe string comprises a casing pipe without a coupling. By means of the self-adaptive expansion characteristic of the self-expansion packer, traditional cement well cementation is replaced, packing failure caused by cement performance fluctuation or casing welting is avoided, and the annulus sealing reliability is improved.

Description

Technical Field

[0001] This invention relates to a multi-packer setting test device, which relates to the field of oil and gas drilling technology and belongs to the field of packer technology in the oil industry. Background Technology

[0002] Casing drilling technology, as an innovative technology in the field of oil drilling, uses casing to replace traditional drill pipe to transmit torque and drilling pressure, enabling drilling and casing running to be completed simultaneously, significantly shortening the drilling cycle and reducing the risk of accidents. However, existing technologies generally rely on cementing processes to isolate the casing annulus, which suffers from unstable cementing quality and the cement sheath being susceptible to pressure-bearing effects from casing edge adhesion or wellbore irregularities.

[0003] Specifically, the existing technology has the following problems: (1) Unstable cementing quality: After the completion of conventional casing drilling, cement is directly injected for cementing. Due to problems such as casing edge adhesion, irregular wellbore, or cement sheath shrinkage, it is easy to form grooves or poor bonding. In addition, the outer wall of the casing is worn and the anti-corrosion layer falls off during the drilling process, which further weakens the sealing performance of the cement sheath and leads to the risk of wellbore integrity in the later stage.

[0004] (2) Strong dependence on cementing materials: Traditional cementing relies on cement slurry system, whose performance is significantly affected by temperature, pressure and formation fluids. In particular, cement slurry leakage or contamination of the producing layer is likely to occur in complex formations.

[0005] (3) Casing eccentricity leads to incomplete sealing: The wellbore size formed by casing drilling is small (e.g., 127mm casing corresponds to a wellbore of 152.4~190.5mm), the annular space is limited, the casing is easy to stick to the well wall, resulting in uneven distribution of cement sheaths and difficulty in achieving full circumference sealing.

[0006] (4) Complex follow-up processing: Conventional cementing requires drilling to remove residual tools such as rubber plugs and graded clamps, which may damage the inner wall of the casing and generate metal debris, increasing operating costs and safety hazards. Summary of the Invention

[0007] To address the aforementioned technical problems in existing technologies, this invention proposes a casing drilling cementless string that utilizes the adaptive expansion characteristics of a self-expanding packer to replace traditional cement cementing, thereby avoiding packer failure caused by fluctuations in cement performance or casing edge adhesion and improving annular sealing reliability.

[0008] This invention proposes a casing drilling cementless tubing string, comprising: A casing string, wherein a drill bit is provided at the lower end of the casing string, and the casing string replaces the drill rod to drive the drill bit to drill. A plurality of self-expanding packers are arranged at intervals along the axial direction of the casing string. The self-expanding packers expand in the presence of an expanding agent and are fixed in the formation. The sleeve string includes a couplingless sleeve.

[0009] A further improvement of the present invention is that the expanding agent is diesel fuel.

[0010] A further improvement of the present invention is that a rubber plug self-locking valve is provided below the sleeve string, and the rubber plug self-locking valve is provided with a triggering mechanism that cooperates with the rubber plug; When a rubber plug is inserted at the wellhead to isolate diesel fuel and slurry fluid, the rubber plug moves to the position of the rubber plug self-locking valve under the pressure of the slurry fluid and connects to the rubber plug self-locking valve, thereby driving the triggering mechanism to close.

[0011] A further improvement of the present invention is that two floating rings are provided above the drill bit, and the rubber plug self-locking valve is provided above the floating rings; the floating rings adopt a one-way check valve structure.

[0012] According to another aspect of the invention, a construction method is also proposed for drilling and cementing using the casing drilling no-cementing string described herein.

[0013] A further improvement of the present invention is that it includes: Assemble the casing drilling cementless tubing string; Drilling is carried out by driving the drill bit through the casing string; Diesel fuel is injected to expand the self-expanding packer.

[0014] A further improvement of the present invention is that, during the diesel injection process, a set amount of diesel is pumped into the casing string, and then a rubber plug is pumped in and driven downward by the slurry liquid, so that the diesel flows into the annulus through the casing string and the drill bit water hole, thereby achieving full contact between the diesel and the self-expanding packer, so that the self-expanding packer completes expansion and sealing within the design time.

[0015] A further improvement of the present invention is that the self-expanding packer is expanded in stages by injecting a predetermined amount of diesel fuel into the annulus in stages.

[0016] A further improvement of the present invention is that, after the self-expanding packer reaches the expansion sealing time, the annulus packer at the wellhead is closed and the annulus is pressurized according to the design pressure to test the expansion sealing of the self-expanding packer, and the pressure test verifies the sealing performance of each packer section. If the sealing test is abnormal, local repairs are carried out by squeezing cement into the annulus of the casing.

[0017] A further improvement of the present invention is that the amount of diesel fuel added is calculated based on the expansion volume of the packer and an additional 10%-15% redundancy is reserved.

[0018] A further improvement of the present invention is that the spacing of the self-expanding packer and the wall thickness of the sleeve are calculated using a crush resistance strength correction formula, wherein the crush resistance strength correction formula is: Among them, P c 'P represents the corrected casing crush resistance strength.' c For standard API extrusion strength, F m Material strength reduction factor (0 <Fm ≤ 1),F s The packer support reinforcement factor (Fs ≥ 1).

[0019] A further improvement of the present invention is that the outer diameter of the casing is 114.3~508mm and the wall thickness is 5.21~16.13mm.

[0020] Compared with the prior art, the present invention has the following advantages.

[0021] The casing-drilling cement-free string of the present invention integrates a self-expanding packer with the casing string. Upon contact with diesel fuel, the packer adapts to the wellbore environment and expands to form a multi-level annular sealing layer. Compared to the incomplete cementing caused by casing edge contact in traditional cementing processes, the packer of the present invention has a maximum expansion rate of up to 600%, effectively avoiding cement slurry channeling or micro-annular phenomena, significantly improving annular sealing and enhancing sealing reliability. Furthermore, the packer layer spacing can be flexibly adjusted according to formation characteristics, further adapting to the sealing requirements of complex well conditions.

[0022] The casing drilling no-cementing string construction method of the present invention simplifies the operation process and significantly improves efficiency: Traditional casing drilling requires cementing operations after drilling completion, involving time-consuming steps such as cement slurry injection and waiting for setting (usually 12-24 hours). The present invention activates the packer by replacing it with diesel fuel, eliminating the need for additional cementing operations and reducing the operation time to 30%-50% of the original process. Furthermore, the design of the rubber plug self-locking valve ensures one-step isolation between the slurry and diesel fuel, avoiding the risk of liquid backflow or mixing, further reducing operational steps and potential failure points.

[0023] The casing drilling method for cement-free tubing described in this invention offers dual optimization in terms of safety and economy. Regarding safety improvements: the self-expanding packer's adaptive characteristics reduce the risk of packer failure due to formation irregularities, and combined with the sealing function of the rubber plug self-locking valve, it reduces the probability of accidents such as blowouts and abnormal annular pressure. Regarding cost reduction: eliminating the use of cementing materials (such as cement) and related equipment reduces the cost per well by an estimated 15%-20%; simultaneously, the shortened overall operation cycle reduces labor and equipment rental costs.

[0024] The casing drilling no-cementing string construction method of the present invention enhances environmental adaptability and is compatible with existing technologies. This string structure is compatible with conventional processes such as directional drilling and logging, and the self-expanding packer has high tolerance for wellbore variation (adapting to wellbore fluctuations within ±10%), making it suitable for the development needs of complex reservoirs such as shale gas and tight oil. The design of the rubber plug self-locking valve also supports the deployment and retrieval of completion tools or staged fracturing operations, expanding the application scenarios of the technology.

[0025] The casing drilling method for cementing-free tubing described in this invention reduces the risk of annular blockage and extends tubing life. In traditional cementing processes, the high density of the cement slurry may carry back sediment or solid phases, causing blockage in small-aperture wellbore locations. This invention avoids this risk through dynamic packing technology. Furthermore, diesel fuel, as the activating medium, is non-corrosive to the casing, further extending the tubing's service life. Attached Figure Description

[0026] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which: Figure 1 The diagram shown is a structural schematic of a casing drilling cementless tubing string according to an embodiment of the present invention. Figure 2 The diagram shown is a structural schematic of a self-expanding packer according to an embodiment of the present invention. Figure 3 The diagram shown is a schematic representation of the self-expanding packer after expansion according to an embodiment of the present invention. Figure 4 The diagram shown is a cross-sectional schematic of a self-expanding packer according to an embodiment of the present invention, illustrating its state before expansion; Figure 5 The diagram shown is a cross-sectional schematic of a self-expanding packer according to an embodiment of the present invention, illustrating its expanded state. Figure 6 The diagram shown is a comparative experimental view of the expansion of the expansion material of a self-expanding packer according to an embodiment of the present invention. Figure 7 The diagram shown is a schematic of a casing drilling cementless tubing string according to an embodiment of the present invention, illustrating the process of slurry replacement after the rubber plug is inserted. Figure 8 The diagram shown is a schematic of a casing drilling cementless string according to an embodiment of the present invention, showing the closed state of the rubber plug self-locking valve; Figure 9 The diagram shown is a schematic diagram of a casing drilling no-cementing string after cementing is completed, according to an embodiment of the present invention. Figure 10 The diagram shown is a structural schematic of a rubber stopper self-locking valve according to an embodiment of the present invention; Figure 11 The diagram shown is a structural schematic of a rubber stopper according to an embodiment of the present invention; Figure 12 The diagram shown is a schematic representation of the structure of a self-locking valve for rubber stoppers according to an embodiment of the present invention, after the valve is connected to the rubber stopper and closed. It should be noted that the accompanying drawings are not necessarily drawn to scale.

[0027] The meanings of the reference numerals in the attached figures are as follows: 1. Casing, 2. Self-expanding packer, 3. Drill bit, 4. Floating collar, 5. Rubber plug self-locking valve, 6. Diesel fuel, 7. Rubber plug, 8. Formation, 9. Slurry displacement fluid, 21. Self-expanding packer body, 22. Expansion material. Detailed Implementation

[0028] To make the technical solutions and advantages of the present invention clearer, exemplary embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not an exhaustive list of all embodiments. Furthermore, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0029] Casing drilling technology, as an innovative technology in the field of oil drilling, uses casing to replace traditional drill pipe to transmit torque and drilling pressure, enabling drilling and casing running to be completed simultaneously, significantly shortening the drilling cycle and reducing the risk of accidents. However, existing technologies generally rely on cementing processes to isolate the casing annulus, which suffers from unstable cementing quality and the cement sheath being susceptible to pressure-bearing effects from casing edge adhesion or wellbore irregularities.

[0030] Specifically, the existing technology has the following problems: (1) Unstable cementing quality: After conventional casing drilling is completed, cement is directly injected for cementing. Due to problems such as casing edge contact, irregular wellbore, or cement sheath shrinkage, it is easy to form grooves or poor bonding. In addition, the outer wall of the casing is worn and the anti-corrosion layer falls off during the drilling process, which further weakens the sealing performance of the cement sheath and leads to the risk of wellbore integrity in the later stage. (2) Strong dependence on cementing materials: Traditional cementing relies on cement slurry system, whose performance is significantly affected by temperature, pressure and formation fluids. Especially in complex formations, cement slurry leakage or contamination of the producing formation is likely to occur. (3) Casing eccentricity leads to incomplete sealing: The wellbore size formed by casing drilling is small (e.g., 127mm casing corresponds to a wellbore of 152.4~190.5mm), the annular space is limited, the casing is easy to stick to the well wall, resulting in uneven distribution of cement sheath and difficulty in achieving full circumference sealing. (4) Complex follow-up processing: Conventional cementing requires drilling to remove residual tools such as rubber plugs and graded clamps, which may damage the inner wall of the casing and generate metal debris, increasing operating costs and safety hazards.

[0031] To address the aforementioned technical problems in existing technologies, this invention proposes a casing drilling cementless string that utilizes the adaptive expansion characteristics of a self-expanding packer to replace traditional cement cementing, thereby avoiding packer failure caused by fluctuations in cement performance or casing edge adhesion and improving annular sealing reliability.

[0032] This implementation example Figure 1 As shown, this embodiment proposes a casing drilling cementless tubing string, comprising: casing, A plurality of self-expanding packers 2 are arranged at intervals along the axial direction of the casing. These self-expanding packers 2 expand in the presence of an expanding agent, thus sealing and fixing the casing within the formation. In the casing drilling cementless string according to this embodiment, the casing is a couplingless casing. The cementless string is composed of the couplingless casing and the self-expanding packer 2. The drill bit 3 and float collar 4 are set below the string to realize casing drilling. The casing string replaces the drill pipe. The casing is run in simultaneously during the drilling process, saving construction procedures and time.

[0033] This embodiment employs a couplingless casing. The couplingless casing avoids the abrupt changes in wellbore diameter caused by traditional threaded coupling connections, reduces stress concentration in the wellbore, and lowers the risk of casing edge contact. In existing casing drilling processes, couplingless casings cannot accommodate accessories such as centralizers, leading to casing deviation, edge contact, and ultimately, packer failure. This embodiment uses a self-expanding packer 2, which expands after the injection of an expanding agent. Its relatively uniform circumferential expansion replaces the function of accessories such as centralizers, centering the casing and preventing deviation or edge contact. More importantly, the self-expanding packer 2 fills the formation after expansion, adapting to the wellbore shape during expansion to form multi-stage sealing sections, replacing traditional cement cementing (such as...). Figure 2-6 (As shown).

[0034] In one embodiment, the expanding agent is diesel oil 6. Diesel oil 6, as an expanding medium, has the characteristics of low viscosity and high permeability, and can quickly fill the internal cavity of the packer to trigger uniform expansion.

[0035] In this embodiment, by integrating the self-expanding packer 2 with the casing string, the packer can adaptively expand upon contact with the diesel fuel 6, forming a multi-level annular sealing layer. Compared to the incomplete cementing problem caused by casing edge contact in traditional cementing processes, the packer in this embodiment can achieve a maximum expansion rate of 600% (e.g., Figure 6 (As shown in the comparative test), it effectively avoids cement slurry channeling or micro-annulus phenomena. At the same time, the packer layer spacing can be flexibly adjusted according to formation characteristics, further adapting to the packing requirements of complex well conditions.

[0036] In one embodiment, such as Figure 10 As shown, a rubber plug self-locking valve 5 is provided below the sleeve string, and the rubber plug self-locking valve 5 is provided with a triggering mechanism that cooperates with the rubber plug. When a rubber plug is inserted at the wellhead to isolate diesel fuel 6 and slurry fluid 9, the rubber plug moves to the position of the self-locking valve 5 under the pressure of the slurry fluid 9, connects to the self-locking valve 5, and drives the triggering mechanism to close (e.g., Figure 11 (As shown).

[0037] In the casing drilling cementless tubing string according to this embodiment, the rubber plug self-locking valve 5 includes a valve body and a triggering mechanism disposed inside it, wherein the valve body is made of a pressure-resistant deformable material, such as a polyurethane-steel skeleton composite structure, and the triggering mechanism is made of a pressure-sensitive spring or a shear pin.

[0038] The rubber stopper isolates the expanding agent below from the slurry fluid 9 above. The slurry fluid 9 drives the rubber stopper downwards, which in turn pushes the expanding agent downwards, allowing it to flow into the annulus through the water inlet of the drill bit 3. During slurry replacement, the rubber stopper is pushed to the self-locking valve position under hydraulic pressure, triggering the mechanism to close and isolating the diesel fuel 6 from the slurry fluid 9, preventing backflow or sinking. After the self-locking valve 5 closes, it forms a physical barrier, ensuring the long-term stability of the annulus seal and preventing fluid crosstalk during subsequent operations.

[0039] In one embodiment, such as Figure 1 As shown, two floating collars 4 are provided above the drill bit 3, and the rubber plug self-locking valve 5 is provided above the floating collars 4; the floating collars 4 adopt a one-way check valve structure.

[0040] In this embodiment, the complete tubing string, from bottom to top, includes a drill bit 3, casing, first float collar 4, casing, second float collar 4, rubber plug self-locking valve 5, casing string and self-expanding packer 2. The casing string is designed according to the design compensation, the length of the self-expanding packer 2 is designed as needed, and the rubber plug has a pressure resistance of 10 MPa / meter or more.

[0041] Replacing cement sheaths with self-expanding packers 2 saves over 30% of cementing time and avoids the quality risks associated with traditional cementing. The packer sleeve is pressure-resistant and customizable in length, making it suitable for fractured and easily collapsible formations. It reduces cement usage and fluid discharge, meeting HSE requirements; the casing has a high reusability rate, lowering drilling costs. The design of the self-locking plug valve 5 ensures accurate and precise fluid displacement and effective locking and isolation between the upper and lower parts.

[0042] Drill bit 3 is preferably a PDC or low-torque roller cone bit 3, and the water hole size must match the pump pressure requirements (6-7MPa) to balance drilling efficiency and casing erosion risk. Float collar 4 adopts a one-way check valve design to prevent drilling fluid backflow and ensure drilling continuity.

[0043] According to another aspect of the invention, a construction method is also provided for drilling and cementing using the aforementioned casing drilling no-cementing string. The construction method includes: Assemble the casing drilling cementless tubing string; Drill bit 3 is driven by the casing string to drill; Diesel fuel 6 is injected to expand the self-expanding packer 2.

[0044] In one embodiment, during the injection of diesel 6, a set amount of diesel 6 is pumped into the casing string, and then a rubber plug is pumped in and driven downward by the slurry liquid 9, so that the diesel 6 flows into the annulus through the casing string and the water hole of the drill bit 3, so that the diesel 6 can fully contact the self-expanding packer 2, thereby enabling the self-expanding packer 2 to complete the expansion and sealing within the design time.

[0045] In one embodiment, the self-expanding packer 2 is expanded in stages by injecting a predetermined amount of diesel fuel 6 into the annulus in stages.

[0046] In one embodiment, after the self-expanding packer 2 reaches its expansion sealing time, the annulus packer at the wellhead is closed and the annulus is pressurized according to the design pressure to test the expansion sealing of the self-expanding packer 2. The pressure test verifies the sealing performance of each packer section. If the sealing test is abnormal, local repairs are carried out by squeezing cement into the annulus of the casing.

[0047] In one embodiment, the amount of diesel fuel 6 is calculated based on the packer expansion volume, with an additional 10%-15% redundancy.

[0048] In one embodiment, the spacing of the self-expanding packer 2 and the wall thickness of the sleeve are calculated using a crush resistance correction formula, wherein the crush resistance correction formula is: Among them, P c 'P represents the corrected casing crush resistance strength.' c For standard API extrusion strength, F m Material strength reduction factor (0 <Fm ≤ 1),F s The packer support reinforcement factor (Fs ≥ 1).

[0049] The derivation process is as follows: Step 1: Theoretical Basis: Standard casing crush strength formula (API 5C3): (Yp = yield strength, t = wall thickness, D = outer diameter) Buckling stability correction: Introducing packer support effect and material reduction effect, based on Timoshenko shell buckling theory: (Supporting conditions) Step 2: Key Coefficient Modeling 1) Material reduction factor Fm Material yield strength decreases under high temperature conditions: (Example: P110 steel grade has Fm=0.85 at 150℃) Packer reinforcement coefficient Fs Relationship between packer spacing L and buckling wavelength: Among them, (L) API API standard calculation length, L eff (Package spacing) Step 3: Formula Derivation Buckling critical pressure correction term (section

[0058] of the document): Considering the coupling effect of material reduction and support strengthening, a dimensionless ratio Fm / Fs is introduced: Coefficient k=0.75 Source: Theoretical derivation: When the packer contact angle θ = 120°, according to the shell support boundary conditions: In one embodiment, the outer diameter of the casing string is 114.3~508mm and the wall thickness is 5.21~16.13mm.

[0050] In one embodiment, the construction method includes the following specific steps: Step 1: Assemble the tubing string and lower it into the ground for initial drilling. A couplingless casing is used as the main body of the drill string, with a PDC drill bit 3 or a roller cone drill bit 3 (preferably a low-torque drill bit 3) connected to the bottom. The casing string is driven to rotate via a top drive device, with the drilling pressure controlled at 10-30 kN, the rotation speed at 60-120 r / min, and the total pump pressure ≤7 MPa, ensuring the stability of the casing string and reducing the risk of bending. During drilling, the drilling pressure and rotation speed are adjusted based on the formation dip data to ensure the verticality of the wellbore.

[0051] Step 2: Activation and sealing of self-expanding packer 2: Each time drilling reaches a predetermined well section (such as through complex formations or producing layers), the self-expanding packer 2 is continuously combined with the casing string. After reaching the designed well depth, the expansion of the packer 2's rubber sleeve is triggered by the osmotic pressure difference between the diesel fuel 6 and the formation fluid. The packer's rubber sleeve is designed to withstand a pressure of 10 MPa / m. After expansion, it adapts to the wellbore morphology, forming an annular sealing layer to replace the traditional cement sheath. The packer spacing is customized according to the reservoir distribution, formation pressure gradient, and wellbore stability requirements to ensure the effectiveness of segmented sealing.

[0052] Step 3: Control and isolation of the rubber stopper self-locking valve 5 with the slurry replacement: After drilling to the designed well depth, the designed amount of diesel oil 6 is pumped into the casing string, followed by the pumping of a rubber plug. Water or mud is used to replace the rubber plug as it descends to the self-locking valve position, triggering a mechanical locking mechanism to form a liquid isolation barrier. The self-locking valve is designed with a bidirectional pressure-bearing structure to prevent the diesel oil 6 from mixing with the replacement mud 9, while also withstanding annular pressure fluctuations. The replaced diesel oil 6 returns to the annulus through the casing string and the drill bit 3's water hole, achieving full contact with the self-expanding packer 2 within the wellbore, allowing the self-expanding packer 2 to expand and seal within the designed time.

[0053] Step 4: Completion and Tubing Integrity Verification: After drilling completion, the casing string is retained as the completion string, and cementing is not required. While replacing the diesel 6 rubber plug with the casing string and pressing it against the self-locking valve, the casing can be pressurized to the test pressure value to test the casing seal. After the self-expanding packer 2 reaches its expansion sealing time, the annulus packer at the wellhead is closed, and the annulus is pressurized to the design pressure to test the expansion sealing of the self-expanding packer 2. The pressure test verifies the sealing performance of each packer section. If any abnormalities are found, local repairs can be performed by injecting cement into the casing annulus.

[0054] Step 5: Finally, install the wellhead equipment and enter the production stage.

[0055] The following description uses specific examples to illustrate the point.

[0056] Example 1 In this embodiment, the casing drilling no-cementing string includes, from bottom to top, drill bit 3 (PDC composite type), casing (Φ139.7mm coupling-free casing), float collar 4 (double float valve structure), casing string (length 800m), self-expanding packer 2 (3 sets, 200m interval, rubber sleeve pressure resistance 10MPa / m), rubber plug self-locking valve 5 (built-in spring locking mechanism), and repeating combination structure (casing string 200m / set + self-expanding packer 2) up to the designed well depth.

[0057] The method for constructing a casing drilling system using the cement-free tubing string described in this embodiment includes the following steps: Drilling during casing string running stage: Drilling is carried out by rotating the casing string through the top drive device, and downhole pressure is monitored in real time.

[0058] After drilling is completed, start the packer: Diesel oil 6 is injected into the casing annulus through the ground pumping system. The self-expanding packer 2 can expand up to 600% after encountering diesel oil 6, forming a three-stage annulus packer zone.

[0059] Rubber stopper isolation operation: The grouting fluid pushes the rubber stopper downward to the self-locking valve position, triggering the spring mechanism to lock it, thus achieving physical isolation between diesel 6 and cement grout. Comparative experiment: Compared with traditional packerless casing drilling: Comparison of curing time with oil self-expanding packer 2: the curing time is shortened to 12 hours (comparative example requires 48 hours to curdle).

[0060] Example 2 In this embodiment, the casing drilling no-cementing string consists of, from bottom to top, a directional drill bit 3 (PDC + bent shell structure), a coupling-free anti-torsion casing (Φ177.8mm high-stretch-resistant casing), a drilling gyroscope measurement system (retrieval type), a rubber plug self-locking valve 5 (with pressure sensor feedback device), and a repeatable combination structure (casing string 150m / set + self-expanding packer 2): Angled section control: The tool face angle is adjusted in real time by the drilling gyroscope, and the casing string can withstand a maximum torque of 18 kN•m. Performance verification: The maximum flexural deformation of the casing string after well completion was less than 2‰, and the packer setting success rate was 100%.

[0061] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should be extended to equivalent substitutions of these features as understood by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0062] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0063] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0064] Certain terms are used throughout this application to refer to specific system components. As those skilled in the art will recognize, the same components may often be referred to by different names, and therefore this application is not intended to distinguish components that differ only in name and not in function. The terms "an embodiment" or "embodiment" used in the specification mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, the phrase "an embodiment" or "embodiment" appearing throughout the specification does not necessarily refer to the same embodiment.

[0065] The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

[0066] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and / or modifications falling within the scope of the invention, and all changes and / or modifications made according to embodiments of the invention should be covered within the protection scope of the invention.

Claims

1. A casing drilling no-cementing string, characterized in that, include: A casing string, the lower end of which is provided with a drill bit (3), the casing string replaces the drill rod to drive the drill bit (3) to drill; A plurality of self-expanding packers (2) are arranged at intervals along the axial direction of the casing string. The self-expanding packers (2) will expand in the environment of the expanding agent and be fixed in the formation. The sleeve string includes a couplingless sleeve (1).

2. The casing drilling cementless tubing string according to claim 1, characterized in that, The expanding agent is diesel oil (6).

3. The casing drilling cementless tubing string according to claim 2, characterized in that, A rubber plug self-locking valve (5) is provided below the sleeve string, and the rubber plug self-locking valve (5) is provided with a triggering mechanism that cooperates with the rubber plug; When a rubber plug is inserted at the wellhead to isolate diesel (6) and slurry fluid (9), the rubber plug moves to the position of the rubber plug self-locking valve (5) under the pressure of the slurry fluid (9) and connects to the rubber plug self-locking valve (5), and drives the triggering mechanism to close.

4. The casing drilling cementless tubing string according to claim 3, characterized in that, Two floats (4) are provided above the drill bit (3), and the rubber plug self-locking valve (5) is provided above the floats (4); the floats (4) adopt a one-way check valve structure.

5. A construction method, characterized in that, Drilling and cementing are performed using a casing drilling no-cementing string according to any one of claims 1 to 4.

6. The construction method according to claim 3, characterized in that, include: Assemble the casing drilling cementless tubing string; Drilling is carried out by driving the drill bit (3) through the casing string; Diesel fuel (6) is injected to expand the self-expanding packer (2).

7. The construction method according to claim 6, characterized in that, During the injection of diesel (6), a set amount of diesel (6) is pumped into the casing string, and then the rubber plug is pumped in and driven downward by the slurry liquid (9), so that the diesel (6) flows into the annulus through the casing string and the water hole of the drill bit (3), so that the diesel (6) can fully contact the self-expanding packer (2), thereby enabling the self-expanding packer (2) to complete the expansion and sealing within the design time.

8. The construction method according to claim 7, characterized in that, The self-expanding packer (2) is expanded in stages by injecting a set amount of diesel oil (6) into the annulus in stages.

9. The construction method according to claim 8, characterized in that, After the self-expanding packer (2) reaches the expansion sealing time, the annulus packer at the wellhead is closed and the annulus is pressurized according to the design pressure to test the expansion sealing of the self-expanding packer (2). The pressure test verifies the sealing performance of each packer section. If the sealing test is abnormal, local repairs are carried out by squeezing cement into the annulus of the casing.

10. The construction method according to claim 9, characterized in that, The amount of diesel fuel (6) to be replaced is calculated based on the packer expansion volume, with an additional 10%-15% redundancy.

11. The construction method according to claim 10, characterized in that, The spacing of the self-expanding packer (2) and the wall thickness of the sleeve are calculated using the anti-crushing strength correction formula, which is: Among them, P c 'P represents the corrected casing crush resistance strength.' c For standard API extrusion strength, F m F is the material strength reduction factor (0 < Fm ≤ 1). s The packer support reinforcement factor (Fs ≥ 1).

12. The construction method according to claim 11, characterized in that, The outer diameter of the casing string is 114.3~508mm, and the wall thickness is 5.21~16.13mm.

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