Soluble shaft reconstruction fracturing process method
Through the soluble wellbore re-engineering fracturing process, the construction parameters are optimized using magnesium alloy materials and Landmark software, which solves the problems of poor pressure bearing properties and complex construction of wellbore re-engineering, and achieves efficient and sealed wellbore reconstruction to meet fracturing needs.
Patent Information
- Application Number
- CN202410034871.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-10
- Publication Date
- 2025-07-11
AI Technical Summary
In the prior art, the pressure bearing capacity of chemical wellbore is poor, which is difficult to meet the high pressure resistance requirements during the later fracturing process. The later pipe column of ordinary wellbore reconstruction does not leave the well, which has an impact on the later oil production. The construction steps are many, the cycle is long, and the sealing is poor.
The soluble wellbore re-fracting process is adopted, and the micro-cell effect is controlled by regulating the alloy element ratio and process of magnesium alloy materials, and the soluble casing is accelerated. Combined with Landmark drilling engineering software, the soluble casing is calculated. The slow-dissolved high-strength magnesium alloy material is used to control the inlet speed and construction parameters, and the whole well section construction is carried out, including water absorption testing, leakage reduction, secondary completion of soluble wellbore re-creation and fracturing transformation.
It achieves high pressure bearing properties of soluble wellbore reconstruction, meets the later fracturing requirements, the soluble column has no effect on oil production, few construction steps and strong sealing, shortening the construction cycle.
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of reservoir stimulation, and particularly relates to a soluble wellbore reconstruction fracturing process method. Background Art
[0002] With the continuous extension of the production time, ultra-low permeability oil reservoirs in oilfields generally face problems such as low production and water breakthrough. In recent years, aiming at low-production horizontal wells and with the goal of volume fracturing, a large-displacement double-packer single-slotted staged fracturing process integrating "comprehensive energy supplementation, dynamic temporary plugging, and simultaneous fracturing" has been formed. However, there are problems such as long construction cycles and high construction costs. Horizontal well volume refracturing is a key technology for tapping the remaining oil in old oilfields, increasing the recovery factor, and the oil production rate. To meet the requirements of the horizontal well repeated high-efficiency staged fracturing process test, it is necessary to carry out research on key tools and processes for horizontal wellbore reconstruction.
[0003] Currently, in the traditional hydraulic fracturing pumping scheme, the following problems exist: (1) The chemical wellbore reconstruction has poor pressure-bearing performance and it is difficult to meet the high pressure resistance requirements during the subsequent fracturing process; (2) The pipe string in the ordinary wellbore reconstruction does not come out of the well in the later stage, which has an impact on the subsequent oil production; (3) The ordinary retrievable wellbore reconstruction has many construction steps, a long construction period, and poor sealing performance.
[0004] Therefore, we propose a soluble wellbore reconstruction fracturing process method to solve the above problems. Summary of the Invention
[0005] The purpose of the present invention is to provide a soluble wellbore reconstruction fracturing process method for the above problems.
[0006] To achieve the above purpose, the present invention provides the following technical solution: A soluble wellbore reconstruction fracturing process method, including the following steps: S1. Research and confirmation of the material of the soluble wellbore reconstruction casing After alloying magnesium with some specific metals, a micro-battery is formed in itself. Under the action of chloride ions, the micro-battery effect is promoted, the continuity of the magnesium surface oxide film is damaged, the purpose of accelerating the magnesium dissolution reaction is achieved, and the effect of the magnesium-water reaction is strengthened. By adjusting the proportion of alloying elements, the reaction rate will also change accordingly. For the requirement of slow dissolution during the service process of the soluble casing, a high-strength magnesium alloy material with slow dissolution is selected. By adjusting the alloy composition and process, the influence of the content, morphology, and distribution of the second-phase aluminum on the corrosion resistance of the alloy is studied. Through the regulation of the second-phase content and distribution, multiple corrosion barriers are constructed to reduce the potential difference between the magnesium matrix and the second-phase, weaken the galvanic corrosion effect, and achieve a slow dissolution of the magnesium alloy at 3-10 mg / (cm2·h), and confirm the casting material of the soluble wellbore; S2. Lower the wellbore casing According to the horizontal wellbore trajectory and the length of the horizontal section, use Landmark drilling engineering software to calculate the mechanical conditions for running 4 1 / 2" soluble casing, and match it with heavy rods and drag reducers, control the running speed to ensure the smooth running of the soluble casing; S3. Water absorption test The string structure (from bottom to top) is a 50° bevel tip + 2 7 / 8" bevel tip plus extra heavy wall tubing to the wellhead. The tubing is run to a position 20 - 30 meters above the perforation cluster. Install a full - closed wellhead, connect the surface pipelines, and test the surface pump truck, wellhead, and pipelines to 35 MPa. Pump in clear water. After the casing returns water, close the casing gate valve, record the pumping displacement and the liquid intake, and calculate the amount of lost - circulation reducing agent according to the specific lost - circulation situation of the formation; S4. Lost - circulation reduction construction Carry out lost - circulation reduction construction by injecting lost - circulation reducing agent in a general way throughout the well section. Control the injection pressure within 20 MPa during construction. If the pressure exceeds the limit, appropriately reduce the displacement. If the wellhead pressure is high and the displacement of displacement water is in place after lost - circulation reduction, do not pull out the drill pipe first. Close the well and install an oil pressure gauge and a casing pressure gauge for pressure monitoring; if the pressure reaches 20 MPa but the injection volume is insufficient, stop lost - circulation reduction, immediately backwash the well and pull out the pipe string or immediately displace and then close the well to measure pressure and wait for setting; if the formation absorption capacity is strong, appropriately increase the concentration and dosage of the lost - circulation reducing agent according to the on - site situation to ensure the success of lost - circulation reduction; after construction, close the well and wait for setting for 96 h; S5. Soluble wellbore reconstruction and secondary completion Use the washing string to replace the wellbore fluid with metal drag - reducing fluid. Prepare the amount of metal drag - reducing fluid according to twice the wellbore volume. Use 3 pieces of 4 1 / 2" casing for simulated casing running, and then run a soluble wellbore throughout the well for cementing operation. Close the well and wait for setting for 48 h; S6. For the first section, use a tubing - carried perforating tool string to perform perforation operations at the specified depth and use open - hole fracturing for transformation. For other sections, adopt the combination operation of soluble bridge plugs and multi - cluster perforation and open - hole fracturing technology; After fracturing, shut - in the well for 30 days, and then carry out sand washing to treat the wellbore.
[0007] In the above - mentioned soluble wellbore reconstruction and fracturing process method, the specifications of the soluble wellbore reconstruction casing material in S1 are: outer Ф114.3 * inner Ф85 mm; tensile strength: ≥340 Mpa; yield strength: ≥240 Mpa; elongation: ≥8%, dissolution time: 3 - 4 months; pressure - bearing capacity: above 60 MPa.
[0008] In the above - mentioned soluble wellbore reconstruction and fracturing process method, the running speed in S2 is controlled to be maintained at 50 - 80 m / h.
[0009] In the above-mentioned soluble wellbore reconstruction fracturing process method, in step S3, the water injection starts from 5 MPa and increases by 5 MPa in each stage, and each stage is stabilized for 3 - 5 minutes.
[0010] Compared with the prior art, the present invention provides a soluble wellbore reconstruction fracturing process method, which has the following beneficial effects: 1. This soluble wellbore reconstruction fracturing process method makes the entire soluble wellbore reconstruction have strong pressure-bearing capacity and meets the requirements of high pressure resistance in the later fracturing process.
[0011] 2. This soluble wellbore reconstruction fracturing process method enables the pipe string of the soluble wellbore reconstruction to be dissolved later and has no impact on later oil production.
[0012] 3. This soluble wellbore reconstruction fracturing process method has fewer construction steps, a short construction period, and strong sealing performance for the soluble wellbore reconstruction.
[0013] In summary: The present invention solves the problems of poor pressure-bearing capacity in the chemical wellbore reconstruction of old wells, the inability of the pipe string to come out of the well in the later stage of ordinary wellbore reconstruction, and the impact on later oil production. Specific Embodiments
[0014] The following embodiments are only for illustrative purposes and are not intended to limit the scope of the present invention.
[0015] Embodiment 1: A soluble wellbore reconstruction fracturing process method includes the following steps: S1. Confirmation of the soluble wellbore reconstruction casing material Select a high-strength magnesium alloy material with slow dissolution. By adjusting the alloy composition and process, the content of the second-phase aluminum is 0.9%. The specifications of this soluble wellbore reconstruction casing material are: outer Ф114.3 * inner Ф85 mm; tensile strength: 350 Mpa; yield strength 244 Mpa; elongation 9%; dissolution time 3.2 months; pressure-bearing capacity 65 MPa; S2. Lower the wellbore casing According to the wellbore trajectory of the horizontal well and the length of the horizontal section, control the lowering speed to be 60 m / h to ensure the smooth lowering of the soluble casing; S3. Water absorption test The pipe string structure (from bottom to top) is 50° bevel tip (2070.0 m) + 2 7The 1 / 8" bevel tip plus external thickened tubing is run to the wellhead. The tubing is run to a depth of 26 meters above the perforation cluster. Install a full-closure wellhead, connect the surface pipeline, and test the surface pump truck, wellhead, and pipeline to 35 MPa. Pump in clear water. After the casing returns water, close the casing gate valve. Starting from 5 MPa, increase by 5 MPa in each stage. Stabilize for 3 - 5 minutes in each stage. Record the pumping displacement of 0.2 - 0.5 cubic meters per minute and the liquid intake of 15 cubic meters. Calculate the amount of lost circulation agent according to the specific lost circulation situation of the formation; S4. Lost circulation reduction construction The lost circulation agent is injected in a general way throughout the entire well section. The construction injection pressure is controlled within 20 MPa. Pump in 400 cubic meters of lost circulation agent. After the construction is completed, shut in the well and wait for cement to set for 96 hours; S5. Soluble wellbore reconstruction and secondary completion Use the washing string to replace the wellbore fluid with metal drag reduction fluid. The amount of metal drag reduction fluid is prepared according to twice the wellbore volume (22.1 cubic meters), that is, 44.2 cubic meters. Use 3 pieces of 4 1 / 2" casing to simulate casing running, and then lower the soluble wellbore into the entire wellbore for cementing operation. Shut in the well and wait for cement to set for 48 hours; S6. In the first stage, use the tubing to carry the perforating tool string to perform perforating operations at the specified depth and use open-hole fracturing for transformation; for the remaining 20 segments, use the soluble bridge plug and multi-cluster perforating combined operation and open-hole fracturing technology; S7. After shutting in the well for 30 days after fracturing, when the wellhead pressure reaches 6.5 Mpa at crack closure, perform sand washing to treat the wellbore.
[0016] Example 2: A soluble wellbore reconstruction fracturing process method includes the following steps: S1. Confirmation of the soluble wellbore reconstruction casing material Select a high-strength magnesium alloy material with slow dissolution. By adjusting the alloy composition and process, the content of the second-phase aluminum is 0.88%. The specification size of this soluble wellbore reconstruction casing material: outer Ф114.3 * inner Ф85 mm; tensile strength: 355 Mpa; yield strength 250 Mpa; elongation 9.8%; dissolution time 3.6 months; pressure-bearing capacity 66 MPa; S2. Lower the wellbore casing According to the horizontal wellbore trajectory and the horizontal section length, control the running speed at 63 m / h to ensure the smooth running of the soluble casing; S3. Water absorption test The string structure (from bottom to top) is 50° bevel tip (2065.0 m) + 2 7Run an 8" beveled tip plus external heavyweight tubing to the wellhead. Lower the tubing to 25 meters above the perforation cluster. Install a full-closure wellhead, connect the surface pipeline, and pressure test the surface pump truck, wellhead, and pipeline to 35 MPa. Pump in clear water. After the casing returns water, close the casing gate valve. Starting from 5 MPa, increase by 5 MPa in each stage. Stabilize for 3 - 5 minutes in each stage. Record the pumping displacement of 0.2 - 0.5 cubic meters per minute and the liquid injection volume of 17 cubic meters. Calculate the amount of lost circulation reducing agent according to the specific lost circulation situation of the formation. S4. Lost circulation reduction construction Carry out the construction by injecting the lost circulation reducing agent in a general way throughout the entire well section. Control the construction injection pressure within 20 MPa. Pump in 450 cubic meters of the lost circulation reducing agent. After the construction is completed, shut in the well and wait for cement setting for 96 hours. S5. Soluble wellbore reconstruction and secondary completion Use the washing string to replace the wellbore fluid with a metal drag reduction fluid. Prepare the amount of the metal drag reduction fluid according to twice the wellbore volume (23.2 cubic meters), that is, prepare 46.4 cubic meters. Use 3 pieces of 4 1 / 2" casing to simulate casing running, and then lower the soluble wellbore into the entire wellbore for cementing operation. Shut in the well and wait for cement setting for 48 hours. S6. For the first stage, use the tubing to carry the perforating tool string to perform perforation operations at the specified depth and use open-hole fracturing for transformation; for the remaining 19 stages, adopt the combination of soluble bridge plugs and multi-cluster perforation and open-hole fracturing technology. After fracturing, shut in the well for 30 days until the wellhead pressure reaches 6.7 Mpa when the fractures are closed, and then wash the wellbore.
[0017] Make the entire soluble wellbore reconstruction have strong pressure-bearing capacity, meet the requirements of high pressure resistance during the later fracturing process, make the tubing of the soluble wellbore reconstruction dissolvable later without affecting the later oil production, make the construction steps of the soluble wellbore reconstruction fewer, the construction period shorter, and the sealing performance stronger, and solve the problems of poor pressure-bearing capacity of the chemical wellbore reconstruction of old wells, the tubing of ordinary wellbore reconstruction not coming out of the well later, and affecting the later oil production.
[0018] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. A soluble wellbore reconstruction fracturing process method, characterized in that, It includes the following steps: S1. Research and confirmation of soluble wellbore reconstruction casing materials After alloying magnesium with some specific metals, a micro-battery is formed, which promotes the micro-battery effect under the action of chloride ions, destroys the continuity of the magnesium surface oxide film, achieves the purpose of accelerating the dissolution reaction of magnesium, strengthens the effect of the magnesium-water reaction. By regulating the proportion of alloying elements, the reaction rate will also change accordingly. For the requirement of slow dissolution during the service process of soluble casing, select high-strength magnesium alloy materials with slow dissolution. By regulating the alloy composition and process, study the influence of the content, microstructure morphology and distribution of the second-phase aluminum on the corrosion resistance of the alloy. Build multiple corrosion barriers through the regulation of the second-phase content and distribution, reduce the potential difference between the magnesium matrix and the second-phase, weaken the galvanic corrosion effect, and achieve slow dissolution of magnesium alloy at 3-10 mg / (cm2·h), and confirm the casting materials of the soluble wellbore; S2. Lower the wellbore casing According to the horizontal wellbore trajectory and the horizontal section length, calculate 4 through the Landmark drilling engineering software 1 For the mechanical conditions of running the 1 / 2" soluble casing, match the heavyweight rod and drag reducer, control the running speed, and ensure the smooth running of the soluble casing; S3. Water absorption test Pipe string structure (from bottom to top): 50° inclined tip + 2 7 / 8" inclined tip plus external upset tubing to the wellhead. The tubing is run to a depth of 20 - 30 meters above the perforation cluster. Install a full-closure wellhead, connect the surface pipelines, and pressure test the surface pump truck, wellhead, and pipelines to 35 MPa. Pump in clear water. After the casing returns water, close the casing gate valve, record the pumping displacement and liquid intake, and calculate the amount of lost circulation additive according to the specific lost circulation situation of the formation; S4. Lost circulation reduction construction Carry out lost circulation reduction agent injection construction in a general way for the whole well section. The construction injection pressure is controlled within 20 MPa. If the pressure exceeds the limit, appropriately reduce the displacement. If the wellhead pressure is high and the displacement of displacement water is in place after lost circulation reduction, do not pull out the drill pipe first. Shut in the well and install an oil pressure gauge and a casing pressure gauge for pressure monitoring; If the pressure reaches 20 MPa but the injection volume is insufficient, stop lost circulation reduction, immediately backwash the well and pull out the pipe string or immediately displace and then shut in the well to measure pressure and wait for setting; If the formation absorption capacity is strong, appropriately increase the concentration and dosage of the lost circulation reduction agent according to the on-site situation to ensure the success of lost circulation reduction; After the construction is completed, shut in the well and wait for setting for 96 h; S5. Soluble wellbore reconstruction and secondary completion Replace the wellbore fluid with a metal drag reduction fluid using a well flushing string. Prepare the amount of the metal drag reduction fluid according to twice the volume of the wellbore. Simulate casing running using 3 pieces of 4 1 / 2" casing, then run a soluble wellbore throughout the wellbore for cementing operations, shut in the well and wait for 48 hours for setting; S6. In the first section, use the tubing to carry the perforating tool string to perform perforating operations at the specified depth, and use open-hole fracturing for transformation. For other sections, adopt the combination of soluble bridge plugs and multi-cluster perforating, and open-hole fracturing technology; S7. After shutting in the well for 30 days after fracturing, wash the wellbore by sand washing.
2. The soluble wellbore reconstruction fracturing process method according to claim 1, wherein The specifications and dimensions of the soluble wellbore reconstruction casing materials in S1 are: outer Ф114.3 * inner Ф85 mm; tensile strength: ≥340 Mpa; yield strength: ≥240 Mpa; elongation: ≥8%, dissolution time: 3-4 months; pressure-bearing capacity: above 60 MPa.
3. A soluble wellbore reconstruction fracturing process method according to claim 1, characterized in that, In S2, control the lowering speed to be maintained at 50-80 m / h.
4. The soluble wellbore reconstruction fracturing process method according to claim 1, wherein, In S3, pump in clear water starting from 5 MPa, with each increase of 5 MPa as a stage, and stabilize for 3-5 minutes at each stage.