Soluble sand control screen pipe, well completion pipe string and method for shale oil long horizontal well

Abstract

The invention belongs to the technical field of oil exploitation, and particularly relates to a soluble sand control screen pipe, a well completion pipe string and a method for a shale oil long horizontal well. The sieve tube at least comprises a sieve tube body, the screen pipe body is made of soluble alloy, a coating is arranged on the surface of the screen pipe body, and a plurality of kerfs are formed in the side wall of the screen pipe body. Connecting threads are respectively arranged on the outer side walls of the upper and lower ends of the screen pipe body. The soluble sand control screen pipe is connected with an oil pipe through the soluble hanging packer, and the shale oil long horizontal well completion pipe string is formed. After fracturing blowout is finished, wellhead pressure relief is completed, and oil pipe operation enters a well through a variable-diameter zone soluble hanging packer and a soluble screen pipe body; and when the soluble suspension packer reaches about 10 parts above a perforation section closest to a wellhead, a soluble ball is thrown for pressing and setting, then releasing is carried out after setting, and production is carried out after an oil pipe is pulled out. According to the soluble sand control screen pipe for the well, formation sand production is prevented from affecting production in the early stage, the screen pipe is gradually dissolved in the later stage, an original shaft is recovered after the well is washed, the well repairing frequency is reduced, and the production time rate is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum exploitation, and in particular relates to a soluble sand control screen pipe, a completion string and a method for a shale oil long horizontal well. Background Art

[0002] my country is rich in shale oil and gas resources, which are mainly distributed in the Ordos, Sichuan, Songliao, Bohai Bay, Junggar and other basins. Exploration and evaluation show that the total shale oil resources alone amount to 11 to 13.5 billion tons. With the continuous advancement of exploration and development technology, especially the breakthrough of horizontal well volume fracturing technology, shale oil development has been piloted in many oil fields.

[0003] The proportion of horizontal wells in shale oil production is high, and most of the horizontal sections are 2000-3000 meters. During the production process, sand is produced in the oil wells, which accumulates and cements near the holes, accompanied by scaling of the wellbore. The impact of sand: First, sand is produced in the horizontal section to form a sand bed, causing blockage; second, the sand is transported upward with the well fluid into the lifting equipment, causing damage to the lifting equipment. Sand may be produced during post-pressurization blowout, drainage and production processes, but as the formation energy gradually depletes, the probability of sand production also gradually decreases. Post-pressurization blowout and sand production: The formation energy is high, the fracture is not completely closed or is in a critical closure state, which is a common phenomenon. Sand production during the drainage stage: The drainage speed is too high or the well is frequently switched on and off, the pressure drop in the fracture is too large or the pressure fluctuates too fast. Sand production during the production process: After the pump is lowered for production, the shale oil horizontal well is initially pumped and sprayed, and the proppant is returned.

[0004] The current foreign proppant anti-backflow technology has gone through three stages of development. In the 1970s, different particle size mixing and irregular propping were used. In the 1990s, fiber particles, thermoplastic materials, and curing resins were used to coat proppants. At present, surface modifiers have been developed. Tail-chasing consolidation sand is still a commonly used measure to prevent proppant backflow, but the cost per well is relatively high.

[0005] Shale oil long horizontal wells produce severe sand in the early stage of production (within 3 years). Conventional sand control screens are put in, but they cannot be fished out in the later stage of well completion, making wellbore treatment difficult.

[0006] After plugging, sand flushing is often used to treat the wellbore. As the formation pressure decreases, the amount of sand flushing loss increases. Some wells with a long production life have serious leakage (loss volume exceeds 2000m 3 ) results in low efficiency of wellbore purification operations, bringing huge challenges to wellbore operations.

[0007] Chinese Patent No.: CN108729888B discloses a self-priming and sinking sand-proof screen, which filters and sand-proofs the materials entering the screen through a filtering device. Chinese Patent No.: CN101328794B discloses a switch-type sand-proof screen, which controls the opening and closing of the screen holes through hydraulic and mechanical control to reduce the frequency of well repair. Chinese Patent No.: CN106593364B discloses a sand-proof screen for gravel filling in horizontal wells, which protects the sand-proof components during production and construction to prevent erosion damage. However, the above patents are not suitable for long horizontal shale oil wells with severe sand production in the early stage of production. Summary of the invention

[0008] The present invention provides a soluble sand control screen pipe, a completion string and a method for a long horizontal shale oil well, with the aim of providing a sand control screen pipe, a completion string and a construction method which have a simple construction process, do not require adjustment of the production system, can be completed through conventional oil pipes, and can maximize shale oil production.

[0009] To achieve the above object, the technical solution adopted by the present invention is:

[0010] A soluble sand control screen for a long horizontal well of shale oil comprises at least a screen body; a plurality of slits are provided on the side wall of the screen body; the screen body is made of a soluble alloy; connecting threads are respectively provided on the outer side walls at the upper and lower ends of the screen body; and a coating is provided on the surface of the screen body.

[0011] The slit width is 0.3-0.4 mm, and the slit length is 180-210 mm; the total flow area is 1%-5% of the surface area of ​​the screen tube body.

[0012] The soluble alloy is a magnesium-aluminum alloy or a zinc-magnesium alloy.

[0013] The surface of the sieve tube body is provided with a low surface energy super hydrophobic coating.

[0014] The low surface energy super hydrophobic coating is prepared by mixing polydimethylsiloxane and nano titanium dioxide in a weight ratio of 2:1-3:1, stirring the mixture evenly, coating the mixture on the surface of the sieve tube body, and then etching the composite coating into micro-nano form by laser after curing.

[0015] A shale oil long horizontal well completion string comprises at least a soluble sand control screen for the shale oil long horizontal well, a soluble hanging packer and an oil pipe; the soluble sand control screen for the shale oil long horizontal well is connected to the oil pipe via the soluble hanging packer.

[0016] The soluble suspension packer is made of magnesium-aluminum alloy or zinc-magnesium alloy; the surface of the soluble suspension packer is provided with a low surface energy super-hydrophobic coating which is the same as the surface of the screen tube body.

[0017] A method for constructing a long horizontal shale oil well, using a shale oil long horizontal well completion string, comprises the following steps:

[0018] Step 1: Wellhead pressure relief

[0019] After the fracturing and blowing are completed, the wellhead pressure relief is completed;

[0020] Step 2: Connect the soluble suspension packer and the soluble screen pipe body through the diameter change of the shale oil long horizontal well completion string and then put it into the well;

[0021] Step 3: Lower the soluble suspension packer to 9-11 meters above the perforation section closest to the wellhead;

[0022] Step 4: Throw in soluble balls to pressurize and seal;

[0023] Step 5: After sealing, release the device and put it into production after pulling out the oil pipe.

[0024] The sealing method is an expansion sealing method using an expansion packer.

[0025] Beneficial effects:

[0026] (1) The soluble sand control screen of the present invention can prevent sand from coming out of the formation at an early stage, effectively avoiding the impact on production. In the later stage, the screen itself gradually dissolves, and the original wellbore is restored after well washing, thereby reducing the frequency of well repair and improving the production time rate.

[0027] (2) The surface of the soluble sand control screen pipe of the present invention is a low surface energy super hydrophobic coating, the main components of which are polydimethylsiloxane and nano titanium dioxide. The composite coating is micronized by laser etching to achieve a super hydrophobic coating, which makes it less likely to scale and clog the cutting seam.

[0028] (3) The construction process of the present invention is simple and the operation can be completed through conventional oil pipes.

[0029] (4) The construction method of the present invention is consistent with the law of sand production in the formation, and there is no need to adjust the production system, thereby maximizing the production of shale oil.

[0030] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 It is a construction flow chart of the present invention.

[0033] Figure 2 A schematic structural diagram of a screen tube body in the present invention.

[0034] Figure 3 It is a structural schematic diagram of a shale oil long horizontal well completion string in the present invention.

[0035] In the figure: 1. Screen tube body; 2. Dissolvable hanging packer; 3. Slit; 4. Oil pipe; 5. Perforation section. DETAILED DESCRIPTION

[0036] 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.

[0037] Embodiment 1:

[0038] according to Figure 2 A soluble sand control screen for a long horizontal well of shale oil is shown, which comprises at least a screen body 1; a plurality of slits 3 are provided on the side wall of the screen body 1; the screen body 1 is made of a soluble alloy; connecting threads are respectively provided on the outer side walls at the upper and lower ends of the screen body 1; and a coating is provided on the surface of the screen body 1.

[0039] In actual use, after the fracturing and blowing are completed, the wellhead pressure is relieved, and the oil pipe 4 is connected to the soluble hanging packer 2 and the soluble screen pipe body 1 through a reducer and then put into the well; then when the soluble hanging packer 2 is 10 meters above the perforation section 5 closest to the wellhead, a soluble ball is thrown to pressurize and seal it; after the seal is set, it is released, and the oil pipe 4 is pulled out and put into production.

[0040] Since the screen pipe body 1 is made of soluble alloy, it has an anti-corrosion sacrificial anode effect when dissolved. The coating has a service life of 2.5-3 years under 40-60℃ formation conditions. After reaching the end of its service life, the coating falls off, and then the screen pipe body 1 of the soluble screen pipe begins to dissolve, and it is completely dissolved in 10-15 days.

[0041] The soluble sand-control screen for shale oil long horizontal wells of the present invention is soluble and keeps the original wellbore intact, which matches the sand production law of shale oil reservoirs. When in use, it can prevent the formation from sand production in the early stage, and the screen itself gradually dissolves in the later stage, and the original wellbore is restored after well washing, which reduces the frequency of well repair and effectively improves the production time rate.

[0042] Embodiment 2:

[0043] according to Figure 2 The soluble sand control screen for long horizontal wells of shale oil shown in the figure is different from the first embodiment in that the slit 3 has a width of 0.3-0.4 mm and a length of 180-210 mm; and the total flow area is 1%-5% of the surface area of ​​the screen body 1.

[0044] In actual use, the width of the slit 3 is set to 0.3-0.4 mm. If the slit width is too small, the seepage capacity will be reduced; if the slit width is too large, the sand control effect will be poor.

[0045] The length of the screen tube body 1 adopts the above technical solution, so that the screen tube body can just be put into the wellbore pocket without blocking the perforation section 5, ensuring the smooth progress of the process.

[0046] In this embodiment, the length of the screen tube body 1 is the distance from the first perforation section 5 in the long horizontal well to the bottom of the artificial well, so as to maximize the sand control of shale oil production.

[0047] Embodiment three:

[0048] according to Figure 2 The soluble sand control screen for a long horizontal well of shale oil shown is different from the first embodiment in that the soluble alloy is a magnesium-aluminum alloy or a zinc-magnesium alloy.

[0049] In actual use, the sand control screen is a component soluble alloy, including but not limited to magnesium-aluminum alloy, zinc-magnesium alloy, etc., which has an anti-corrosion sacrificial anode effect when dissolved.

[0050] The sand screen is made of soluble alloy. When the coating reaches the end of its life, the coating falls off and the screen body 1 of the soluble screen begins to dissolve. It will be completely dissolved in 10-15 days. After the well is washed, the original wellbore is restored, the frequency of well repair is reduced, and the production time rate is improved.

[0051] The present invention can be operated through conventional oil pipes and can maximize sand control in shale oil production.

[0052] Embodiment 4:

[0053] according to Figure 2 The soluble sand control screen for a long horizontal well of shale oil shown is different from the first or second embodiment in that a low surface energy super hydrophobic coating is provided on the surface of the screen body 1 .

[0054] In actual use, a low surface energy super-hydrophobic coating is provided on the surface of the sieve tube body 1 to make the surface of the sieve tube body 1 super-hydrophobic and prevent the surface from scaling, thereby avoiding clogging of the slit 3 .

[0055] Embodiment five:

[0056] according to Figure 2The soluble sand control screen for long horizontal wells of shale oil shown in the figure is different from that of Example 4 in that: the low surface energy super hydrophobic coating is prepared by mixing polydimethylsiloxane and nano titanium dioxide in a weight ratio of 2:1-3:1, stirring the mixture evenly, coating the mixture on the surface of the screen body 1, and then etching the composite coating into micro-nano form by laser after curing.

[0057] In actual use, the main components of the low surface energy super hydrophobic coating are polydimethylsiloxane and nano titanium dioxide. The composite coating is micronized by laser etching to achieve a super hydrophobic coating, which makes it difficult for the surface to scale and clog the cutting seam. The coating has a lifespan of 2.5-3 years under 40-60°C formation conditions. After reaching the end of its lifespan, the coating falls off, exposing the surface of the soluble screen tube body 1, and then begins to dissolve. It will be completely dissolved in 10-15 days. After washing the well, the original wellbore can be restored, reducing the frequency of well repairs.

[0058] Embodiment six:

[0059] according to Figure 2 and Figure 3 The shale oil long horizontal well completion string shown includes at least a soluble sand control screen for the shale oil long horizontal well, a soluble hanging packer 2 and an oil pipe 4; the soluble sand control screen for the shale oil long horizontal well is connected to the oil pipe 4 through the soluble hanging packer 2.

[0060] Furthermore, the soluble suspension packer 2 is made of magnesium-aluminum alloy or zinc-magnesium alloy; the surface of the soluble suspension packer 2 is provided with a low surface energy super-hydrophobic coating which is the same as the surface of the screen tube body 1 .

[0061] In actual use, after the fracturing and blowing are completed, the wellhead is depressurized, and the oil pipe is connected to the soluble hanging packer 2 and the soluble screen pipe 1 through a reducer and then put into the well; the soluble hanging packer 2 is lowered to 10 meters above the perforation section 5 closest to the wellhead; the soluble ball is thrown in to pressurize and seal; after the seal is set, it is released and the oil pipe is pulled out and put into production.

[0062] The coatings on the surface of the soluble suspension packer 2 and the screen tube body 1 have a service life of 2.5-3 years under 40-60°C formation conditions. After reaching the service life, the coatings fall off, exposing the surfaces of the soluble screen tube body 1 and the soluble suspension packer 2. Then both begin to dissolve, and are completely dissolved in 10-15 days. After well washing, the original wellbore can be restored, reducing the frequency of well repair.

[0063] The low surface energy super hydrophobic coating, whose main components are polydimethylsiloxane and nano-titanium dioxide, is micronized by laser etching to achieve a super hydrophobic coating that is not prone to scaling and clogging the cutting seams.

[0064] The oil pipe 4 in this embodiment is a conventional oil pipe. The present invention can be completed by using a conventional oil pipe, which can maximize the sand control of shale oil production, save costs, and is easy to implement.

[0065] Embodiment seven:

[0066] Reference Figure 1-Figure 3 A method for constructing a long horizontal shale oil well, using a shale oil long horizontal well completion string, comprises the following steps:

[0067] Step 1: Wellhead pressure relief

[0068] After the fracturing and blowing are completed, the wellhead pressure relief is completed;

[0069] Step 2: insert the shale oil long horizontal well completion string into the well through the variable diameter belt soluble hanging packer 2 and the soluble screen;

[0070] Step 3: lower the soluble suspension packer 2 to 9-11 meters above the perforation section 5 closest to the wellhead;

[0071] Step 4: Throw in soluble balls to pressurize and seal;

[0072] Step 5: After sealing, release the device and start production after pulling out the oil pipe 4.

[0073] Furthermore, the sealing method is an expansion sealing method using an expansion packer.

[0074] In actual use, the adoption of the above technical solution has a simple construction process and can be completed through conventional oil pipe operations. The soluble sand screen technology for long horizontal wells of shale oil is consistent with the sand production law of the formation, and there is no need to adjust the production system, maximizing shale oil production.

[0075] The sealing method in this embodiment adopts an expandable packer for expansion sealing, which can improve the safety and reliability of high temperature and high pressure resistance, and has low cost and high construction efficiency.

[0076] Embodiment eight:

[0077] In the H4-A well, the horizontal section is 1,500 meters long. After the fracturing and blowing are completed, the wellhead is depressurized, and the 2-inch 7-tubing operation is completed. A soluble hanging packer with a 4.5-inch reducer and a soluble screen pipe body of 1,500 meters are put into the well; when the soluble hanging packer is 10 meters above the perforation section 5 closest to the wellhead, a soluble ball is thrown in to pressure and seal it; after the seal is set, it is released and the tubing is pulled out and put into production.

[0078] After being put into production, the cumulative production in the first three years increased by 105% compared with the neighboring wells without screens. After three years, the soluble screen dissolvers were washed out of the well, and the wellbore remained unobstructed, and there was no blockage due to sand production in the later period.

[0079] Embodiment nine:

[0080] Hua H21-A Well has a horizontal section of 2,300 meters. After the fracturing and blowing were completed, the wellhead was depressurized, and a 2-inch 7-tubing operation was completed. A 4.5-inch soluble hanging packer and a soluble screen of 2,300 meters were put into the well through a reducer. When the soluble hanging packer was 10 meters above the perforation section 5 closest to the wellhead, a soluble ball was thrown in to pressure and seal it. After the seal was set, it was released and the tubing was pulled out before going into production.

[0081] After being put into production, the cumulative production in the first three years increased by 113% compared with the neighboring wells without screens. After three years, the soluble screen dissolvers were washed out of the well, and the wellbore remained unobstructed, and there was no blockage due to sand production in the later period.

[0082] Embodiment ten:

[0083] Hua H15-A Well has a horizontal section of 1,800 meters. After the fracturing and blowing were completed, the wellhead was depressurized, and a 2-inch 7-tubing operation was performed. A 4.5-inch soluble hanging packer and a soluble screen pipe of 1,800 meters were put into the well through a reducer. When the soluble hanging packer was 10 meters above the perforation section 5 closest to the wellhead, a soluble ball was thrown in to pressure and seal it. After the seal was set, it was released and the tubing was pulled out before production began.

[0084] After being put into production, the cumulative production in the first three years increased by 176% compared with the neighboring wells without screens. After three years, the soluble screen dissolvers were washed out of the well, and the wellbore remained unobstructed, and there was no blockage due to sand production in the later period.

[0085] Embodiment eleven:

[0086] Hua H101-A Well has a horizontal section of 3,500 meters. After the fracturing and blowing were completed, the wellhead was depressurized, and a 2-inch 7-tubing operation was completed. A 4.5-inch soluble hanging packer and a soluble screen of 3,500 meters were put into the well through a reducer. When the soluble hanging packer was 10 meters above the perforation section 5 closest to the wellhead, a soluble ball was thrown in to pressure and seal it. After the seal was set, it was released and the tubing was pulled out before going into production.

[0087] After being put into production, the cumulative production in the first three years increased by 155% compared with the neighboring wells without screens. After three years, the soluble screen dissolvers were washed out of the well, and the wellbore remained unobstructed, and there was no blockage due to sand production in the later period.

[0088] In the absence of conflicts, technicians in this field can combine the relevant technical features in the above examples according to actual conditions to achieve corresponding technical effects. The specific combinations are not described here one by one.

[0089] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0090] In addition, the descriptions of "first", "second", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0091] The above are only preferred embodiments of the present invention. The present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features disclosed herein. Any simple modification, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A soluble sand control screen for a long horizontal well of shale oil, characterized by: The invention comprises at least a screen tube body (1); a plurality of slits (3) are provided on the side wall of the screen tube body (1); the screen tube body (1) is made of a soluble alloy; connecting threads are respectively provided on the outer side walls at the upper and lower ends of the screen tube body (1); and a coating is provided on the surface of the screen tube body (1).

2. A soluble sand control screen for a long horizontal well of shale oil as claimed in claim 1, characterized in that: The slit width of the slit (3) is 0.3-0.4 mm, and the slit length is 180-210 mm; the total flow area is 1%-5% of the surface area of ​​the screen tube body (1).

3. A soluble sand control screen for a long horizontal well of shale oil as claimed in claim 1, characterized in that: The soluble alloy is a magnesium-aluminum alloy or a zinc-magnesium alloy.

4. A soluble sand control screen for a long horizontal well of shale oil as claimed in claim 1 or 2, characterized in that: The surface of the sieve tube body (1) is provided with a low surface energy super hydrophobic coating.

5. A soluble sand control screen for a long horizontal well of shale oil as claimed in claim 4, characterized in that: The low surface energy super hydrophobic coating is prepared by mixing polydimethylsiloxane and nano titanium dioxide in a weight ratio of 2:1-3:1 and stirring them uniformly, coating the mixture on the surface of the sieve tube body (1), and then etching the composite coating into micro-nano form by laser etching after curing.

6. A shale oil long horizontal well completion string, characterized by: The invention comprises at least the soluble sand control screen for long horizontal shale oil wells as claimed in any one of claims 1 to 5, and also comprises a soluble hanging packer (2) and an oil pipe (4); the soluble sand control screen for long horizontal shale oil wells is connected to the oil pipe (4) via the soluble hanging packer (2).

7. A shale oil long horizontal well completion string as claimed in claim 6, characterized in that: The soluble suspension packer (2) is made of magnesium-aluminum alloy or zinc-magnesium alloy; the surface of the soluble suspension packer (2) is provided with a low surface energy super-hydrophobic coating which is the same as the surface of the screen tube body (1).

8. A method for constructing a long horizontal shale oil well, characterized in that: The shale oil long horizontal well completion string as claimed in claim 7 or 8 comprises the following steps: Step 1: Wellhead pressure relief After the fracturing and blowing are completed, the wellhead pressure relief is completed; Step 2: Connect the soluble suspension packer (2) and the soluble screen pipe body (1) through a diameter change in the shale oil long horizontal well completion string and then put it into the well; Step 3: lowering the soluble suspension packer (2) to 9-11 meters above the perforation section (5) closest to the wellhead; Step 4: Throw in soluble balls to pressurize and seal; Step 5: After setting the seal, release the cap and pull out the oil pipe (4) before putting it into production.

9. A method for constructing a long horizontal shale oil well as claimed in claim 8, characterized in that: The sealing method is an expansion sealing method using an expansion packer.

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