A process for annulus filling of a locally hanging well section

Abstract

The application discloses a local hanging well section annular filling process method, which comprises the following steps: lowering a pipe string; after the pipe string is lowered into position, circulating well washing; after the well washing, pumping filling liquid; after the pumping of the filling liquid, pumping displacement liquid; and after the pumping of the displacement liquid, waiting for solidification. The local hanging well section annular filling process method can realize annular filling of a local hanging well section.

Description

Technical Field

[0001] This invention relates to the field of cementing, and more particularly to a method for filling the annulus in a partially suspended well section. Background Technology

[0002] In the oil industry, casing needs to be installed in drilled wells, and the annulus between the casing and the wellbore needs to be filled with cement and cured to form a sealed support or locally filled with other materials. In some cases, the design requires cement slurry to be filled into the annulus of local suspended sections for cementing, while cement filling is not allowed in the annulus of the bottom section of the well. The currently used technical solutions and methods cannot be used for cementing or filling operations of local suspended sections of wells with special requirements such as those requiring intermediate circulation, large-sized irregular wells, and weak formations. Summary of the Invention

[0003] This invention provides a process for filling the annulus in a partially suspended well section, which can achieve the filling of the annulus in a partially suspended well section.

[0004] An embodiment of the present invention provides a method for filling the annulus of a partially suspended well section, comprising: running a tubing string; circulating and flushing the well after the tubing string is in place; pumping in filling fluid after circulating and flushing; pumping in displacement fluid after pumping in the filling fluid; and waiting for the displacement fluid to solidify.

[0005] In some embodiments, before running the tubing string, an umbrella-shaped deformable support device of appropriate size is selected according to the wellbore conditions and fixed to the casing.

[0006] In some embodiments, if obstruction is encountered during tubing string installation, a positive circulation well flush is performed.

[0007] In some embodiments, during well flushing, the well is flushed through the bypass holes of the multi-aperture stepped bypass sleeve short section.

[0008] In some embodiments, during well flushing via the bypass hole of the multi-aperture stepped bypass sleeve, a No. 1 ball is dropped into the pipe. After the ball falls, the pump is started, pressure is built up, the bypass hole of the multi-aperture stepped bypass sleeve opens, and then well flushing is performed.

[0009] In some embodiments, after circulating well washing, ball #3 is dropped, and after the ball falls, the pump is started, pressure is built up, and the self-priming function of the plate valve is activated.

[0010] In some embodiments, after the pump is started, the pressure is observed. If the pressure cannot be stabilized, an attempt is made to re-pressurize or throw ball #2 to make the pump pressure rise and stabilize.

[0011] In some embodiments, the well is flushed via positive circulation before flushing through the bypass holes of the multi-aperture stepped bypass sleeve short section.

[0012] In some embodiments, after positive circulation well flushing, an annular special protective fluid is introduced and the annular special protective fluid is replaced from the casing shoe to the annular position of the well section, and then the well is flushed through the bypass hole of the multi-pore stepped bypass sliding sleeve short section.

[0013] In some embodiments, when pumping the filling fluid, a release fluid is pumped, followed by cement slurry. When pumping the displacement fluid, seawater or fresh water is pumped.

[0014] An embodiment of the present invention provides a method for filling the annulus of a partially suspended well section, comprising: running a tubing string; circulating and flushing the well after the tubing string is in place; pumping a filling fluid after circulating and flushing the well; pumping a displacement fluid after pumping the filling fluid; and waiting for the displacement fluid to solidify. The method for filling the annulus of a partially suspended well section of the present invention can achieve annulus filling of a partially suspended well section. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the tubular column structure in an embodiment of the present invention;

[0017] Figure 2 This is a flowchart illustrating the operation process of the annulus filling method for partially suspended well sections in an embodiment of the present invention.

[0018] Figure 3 This is a schematic diagram of the tubular column before filling in Embodiment 1 of the present invention;

[0019] Figure 4 This is a schematic diagram of the tubular column after filling in Embodiment 1 of the present invention;

[0020] Figure 5 This is a schematic diagram of the tubular column before filling in Embodiment 2 of the present invention;

[0021] Figure 6 This is a schematic diagram of the tubular column after filling in Embodiment 2 of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] See Figure 1-2The present invention provides a method for filling the annulus of a partially suspended well section, comprising:

[0024] (1) Lower tubing.

[0025] The tubing string is a series structure, specifically consisting of: 1 guide shoe or self-filling float shoe or casing guide tool (optional) × 1 + 5 casings × N1 + 5 casings × 1 to 2 with deformable support devices on the outer wall and an umbrella-shaped skeleton + 3 multi-diameter stepped bypass sliding sleeves (optional, self-resetting function) × 1 + 5 casings × N2 + 4 self-filling valves × 1 + 5 casings × N3 + 4 feed-in drill strings (optional). All components are connected by threads through casings 5. The lower tubing string is also called the lower casing.

[0026] Before running the tubing string, select an umbrella-shaped deformable support device 2 of appropriate size according to the wellbore conditions and fix it on the casing 5. The umbrella-shaped deformable support device 2 includes two rods, one end of which is fixed to the opposite sides of the casing 5, and the other side is inclined away from the guide shoe 1.

[0027] If obstruction is encountered during casing string installation, a forward circulation well flushing process is initiated. This means that the flushing fluid flows out from the guide shoe 1 along the internal fluid channel of casing 5, and then flows out from the wellbore opening along the external fluid channel of casing 5; this is also known as casing shoe circulation. During casing 5 installation, the wellbore has a bidirectional fluid channel, enabling automatic grouting throughout the entire casing 5 installation process and allowing for continuous forward circulation by starting the pump at any time, ensuring the safe installation of casing 5 under complex wellbore conditions.

[0028] (2) After the tubing string is lowered into place, the well is circulated and flushed.

[0029] During the circulation well washing process, the well is circulated through the bypass holes of the multi-aperture stepped bypass sliding sleeve short section 3, also known as bypass circulation.

[0030] When circulating and flushing the well through the bypass hole of the multi-aperture stepped bypass sliding sleeve short section 3, drop ball #1 into the pipe. After the ball falls, start the pump at a low displacement to build up pressure (e.g., 4-6 MPa). The bypass hole of the multi-aperture stepped bypass sliding sleeve short section 3 will open, and then the well will be flushed. After flushing, drop ball #3. After the ball falls, start the pump to build up pressure (3-5 MPa), and the self-priming function of the plate valve will be activated.

[0031] After starting the pump, observe the pressure buildup. If the pressure cannot be stabilized, try re-pressurizing or adding ball #2 to increase and stabilize the pump pressure. Observe the pressure buildup by pressing for 1-2 MPa to check for blockages in the pipe passage.

[0032] Before circulating the well through the bypass hole of the multi-aperture stepped bypass sliding sleeve short section 3, a direct circulation well flushing, also known as pipe shoe circulation, is performed. In this process, the pump is started directly for circulation well flushing without opening the bypass hole. During the above process, the circulation pressure is controlled to be less than 6 MPa (adjustable).

[0033] After the positive circulation well washing, the annular special protective fluid is introduced and replaced from the casing shoe to the annular position of the well section. Then, the well is circulated and washed through the bypass hole of the multi-pore stepped bypass sliding sleeve short section 3.

[0034] (3) Pump filling fluid after circulating well washing.

[0035] During the pumping of filling fluid, isolation fluid is pumped in, followed by cement slurry.

[0036] (4) Pump in the filling fluid and then pump in the displacement fluid.

[0037] After pumping in the filling fluid, the rubber plug can be released (also known as plug insertion), and then the displacement fluid can be pumped in. If the tubing string is a "drill pipe string conveying casing string", the rubber plug uses a conventional tailpipe rubber plug group of "drill pipe rubber plug + casing hollow rubber plug"; if the tubing string is a "casing string", the rubber plug uses a conventional casing rubber plug, in which case the pressure-pressing mode is used. If the rubber plug is not released, a quantitative displacement mode can be used.

[0038] When pumping the displacement fluid, use seawater or fresh water.

[0039] (5) Wait for the displacer to solidify after pumping in the liquid.

[0040] In related technologies, the top cementing process uses a combination of "blind plate + casing external packer + casing stage collar" to achieve the process objective. However, this process has four major problems in application: ① The casing external packer has limited expansion size and is not suitable for large or irregular annulus. ② The presence of the blind plate on the tubing string results in a closed channel inside the casing, making it unsuitable for well conditions requiring circulation during casing running. ③ The casing stage collar requires a special stage collar closure plug to close the circulation space and prevent annular fluid backflow. This closure plug cannot be used for casing string assemblies with drill pipe, but only for full-well casing string assemblies. ④ Both the casing external packer and the casing stage collar are hydraulically operated. The casing stage collar opens at high pressure, and the release of high-pressure fluid into the annulus can lead to leakage in weak formations.

[0041] The related technologies have the following problems:

[0042] 1. Unable to perform circulation at the shoe tube.

[0043] Traditional processes have sealing devices inside the casing, which prevent circulation from the casing shoe and cannot handle situations such as obstruction during the process under complex wellbore conditions such as irregularity, instability, and narrow gaps.

[0044] 2. Irregular wellbore annulus prevents cement slurry from settling.

[0045] Traditional processes use the expansion of the packer sleeve to seal the annulus. However, for irregular wellbores or large annular spaces, the packer sleeve cannot contact the well wall, thus failing to prevent cement slurry from settling in the annulus.

[0046] 3. Pipe string structures that cannot be used for drill pipe delivery

[0047] The casing grading collar needs to be closed with a special grading collar shut-off plug to prevent annular fluid backflow. This shut-off plug cannot be used for casing string assemblies fed into the drill pipe; it can only be used for casing string assemblies throughout the well.

[0048] 4. Cannot be used in wells with weak formations.

[0049] Both the casing packer and the casing stage clamp are hydraulically operated. The casing stage clamp opens at a high pressure, and the release of high-pressure gas into the annulus can lead to leakage in weak formations.

[0050] This invention solves four major problems and limitations of traditional top cementing cementing processes. It can be used for cementing or filling operations in situations such as irregular well sections in large annulus, cases where there is a need for circulation from the casing shoe during casing installation, non-full-well casing string structures, and weak formations, achieving the purpose of cementing and filling locally suspended well sections in the annulus.

[0051] The following detailed description is provided with reference to specific embodiments:

[0052] See Figure 3-4 A well with a borehole diameter of 311.1 mm and a depth of 350 m was drilled in an area with a water depth of 100 m. Oil casing 5, since the wellbore is located underwater, requires the tubing string to be sent in using a 139.7mm drill pipe. It is required that only the wellbore annulus below the mud surface be filled with cement, and the annulus below the bottom 150m of the well is not allowed to be filled with cement slurry.

[0053] Step 1: The wellbore size is 311.1mm. Considering the wellbore enlargement rate, select two umbrella-shaped deformable support devices 2 with a deformation size of 450-320mm and fix them on the casing string. Set the opening pressure of the multi-hole stepped bypass sliding sleeve 3 to 3-5MPa and the pressure of the self-filling valve 4 to 2-3MPa. Connect the casing string and drill pipe string in sequence and run them down. Due to the loose well wall, if the running process encounters resistance, the pump can be started for circulation. Note that the pump pressure at the wellhead should not exceed 3MPa.

[0054] Step 2: Lower the tubing into place, drop ball #1 from the drill pipe, wait for the ball to fall for 20 minutes, slowly start the pump at a flow rate of 10L / min, the pump pressure rises and stabilizes, pressurize to 4MPa, the pressure drops suddenly, and the bypass hole opens;

[0055] Step 3: Circulation at a displacement of 30-40 L / min;

[0056] Step 4: Insert ball #3 into the drill pipe and wait for the ball to fall for 20 minutes. Slowly start the pump at a flow rate of 10L / min. The pump pressure rises and stabilizes. When the pressure reaches 2.5MPa, the pressure drops suddenly and the plate valve opens.

[0057] Step 5: Connect the wellhead manifold, pump in the isolation fluid, pump in the cement slurry, and pump in seawater to displace the pipe until a 50m cement plug is left inside.

[0058] Step 6: Wait for it to solidify.

[0059] Example 2

[0060] See Figure 5-6 A certain well is a permafrost exploration well with a depth of 300m. A 215.9mm drill bit is run into a 177.8mm casing 5. The requirement is to secure measuring instruments to the outside of casing 5 and transmit data to the wellhead via fiber optic cable outside casing 5. The monitoring section is the 200-300m well section. To simplify the well structure, there is no upper casing 5. The annulus from 200m to the wellhead must be fully sealed to prevent the influence of surface pressure fluctuations and other factors. The annulus from 200-300m should not be filled with cement to prevent clogging of the measuring instruments.

[0061] Step 1: The wellbore size is 215.9mm. Considering the wellbore enlargement rate, select two umbrella-shaped deformable support devices with a deformation size of 220-280mm and fix them on the casing string. Set the opening pressure of the multi-hole stepped bypass sliding sleeve short section 3 to 3-5MPa and the pressure of the self-filling valve 4 to 2-3MPa. Connect the casing string and drill pipe string in sequence and run them down. Due to the loose well wall, if the running process encounters resistance, the pump can be started for circulation. Note that the pump pressure at the wellhead should not exceed 3MPa.

[0062] Step 2: Lower the tubing string into position, slowly start the pump, establish a bottom hole circulation channel and ensure smooth circulation; replace the annulus with special protective fluid and push it from the casing shoe to the annulus position in the 200-300m section of the well.

[0063] Step 3: Insert ball #1, wait for the ball to fall for 5 minutes, slowly start the pump at a displacement of 10L / min, the pump pressure rises and stabilizes, pressurize to 4MPa, the pressure drops suddenly, and the bypass hole opens;

[0064] Step 4: Circulate the fluid at a displacement of 30-40 L / min from a position of 200 m.

[0065] Step 5: Insert ball #3 into wellhead casing 5. After the ball falls for 5 minutes, slowly start the pump at a flow rate of 10L / min. The pump pressure rises and stabilizes. When the pressure reaches 2.5MPa, the pressure drops suddenly and the plate valve function is activated.

[0066] Step 5: Connect the wellhead manifold, pump in the isolation fluid, pump in the cement slurry, release the rubber plug at the wellhead, and pump in fresh water to displace it until pressure is applied;

[0067] Step 6: Wait for it to solidify.

[0068] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this invention, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device 1 or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for filling the annulus of a partially suspended well section, characterized in that, include: Down tubing; After the tubing string is lowered into place, the well is flushed using a circulation system. After circulating well washing, filler fluid is pumped in; Pump in the filling fluid, then pump in the displacement fluid; Wait for the displacer to solidify after pumping in the liquid.

2. The method for filling the annulus of a partially suspended well section as described in claim 1, characterized in that, Before running the tubing string, select an umbrella-shaped deformable support device of appropriate size according to the wellbore conditions and fix it on the casing.

3. The method for filling the annulus of a partially suspended well section as described in claim 1, characterized in that, If obstruction is encountered during tubing string installation, the well is flushed using positive circulation.

4. The method for filling the annulus of a partially suspended well section as described in claim 1, characterized in that, During well flushing, the well is flushed through the bypass holes of the multi-aperture stepped bypass sliding sleeve short section.

5. The method for filling the annulus of a partially suspended well section as described in claim 4, characterized in that, When circulating and flushing the well through the bypass hole of the multi-aperture stepped bypass sliding sleeve short section, drop a No. 1 ball into the pipe. After the ball falls, start the pump, pressurize, and the bypass hole of the multi-aperture stepped bypass sliding sleeve short section will open. Then, circulate and flush the well.

6. The method for filling the annulus of a partially suspended well section as described in claim 5, characterized in that, After circulating and washing the well, drop ball #3. After the ball falls, start the pump, pressurize, and activate the self-priming function of the plate valve.

7. The method for filling the annulus of a partially suspended well section as described in claim 5, characterized in that, After starting the pump, observe the pressure buildup. If the pressure cannot be stabilized, try to build up the pressure again or throw in ball #2 to make the pump pressure rise and stabilize.

8. The method for filling the annulus of a partially suspended well section as described in claim 4, characterized in that, Before circulating the well through the bypass hole of the multi-aperture stepped bypass sliding sleeve short section, perform forward circulation well cleaning.

9. The method for filling the annulus of a partially suspended well section as described in claim 8, characterized in that, After positive circulation well washing, special protective fluid for the annulus is introduced and replaced from the casing shoe to the annulus position of the well section. Then, the well is circulated and washed through the bypass hole of the multi-pore stepped bypass sliding sleeve short section.

10. The method for filling the annulus of a partially suspended well section as described in claim 1, characterized in that, When pumping the filling fluid, pump the isolation fluid first, and then pump the cement slurry. When pumping the displacement fluid, use seawater or fresh water.

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