A consolidated plugging slurry for plugging a flow water thief zone, a plugging method and applications

Abstract

The application belongs to the technical field of plugging for oil drilling, and particularly relates to a consolidated plugging slurry for plugging a flow water lost layer, a plugging method and application. The consolidated plugging slurry for plugging the flow water lost layer comprises the following raw material components in parts by weight: consolidated material 110-150 parts, consolidated particles 60-100 parts, activator 2-3 parts, retarder 2-6 parts, weighting agent 0-50 parts, and water 100 parts. The consolidated plugging slurry of the application does not accumulate under flowing water, the underwater consolidated particles can form a permeation layer and stay in the fracture, and can be solidified after a period of time under the formation temperature and pressure environment to form consolidated objects with certain strength, thereby solving the lost circulation problem of the flow water layer. The consolidated body has low strength, and it is not easy to drill a new wellbore after the plug is left in the wellbore.

Description

Technical Field

[0001] This invention belongs to the field of oil drilling leak sealing technology, specifically relating to a consolidation leak sealing slurry for sealing leaks in flowing water leakage layers, a leak sealing method, and its application. Background Technology

[0002] As oil and gas exploration and development expands into deeper, ultra-deep, and unconventional resource areas, factors such as more complex formations, longer open-hole sections, and multiple pressure systems have led to frequent drilling fluid losses, making plugging increasingly difficult. For example, encountering loss-making formations containing high-pressure water and flowing water has become one of the major technical challenges plaguing drilling. In the upper section of the Xiaganchaigou Formation in the Yingxiongling area of ​​Qinghai Oilfield, fractures are well-developed, and different pressure systems exist within the same open-hole section, encountering multiple high-pressure water layers. Conventional bridge plugging combined with cement plugging methods have low success rates. In the Nanchuan shale gas field, shallow drilling encountered loss-making layers containing active water, forcing drilling with clear water or relocation of the well, severely impacting the exploration and development process.

[0003] For the remediation of leaks involving flowing water, regardless of whether it's bridging, cement, gel + cement, or bridging + cement, these methods are not ideal. If bridging is used, the cohesion between particles in the bridging sealing layer is low. When pressure is released from the wellbore, the flowing water in the leakage channel can easily dissipate the sealing layer, leading to sealing failure. If consolidation is used, the sealing slurry is easily diluted or washed away by groundwater flow, resulting in reduced viscosity and concentration, making it difficult to solidify. After dilution, the setting strength of the slurry is significantly reduced, or it may fail to form an effective sealing layer. Current sealing methods all aim to completely seal the leakage channel, preventing groundwater from passing smoothly through the sealing layer. This causes water to accumulate within the channel, which in turn leads to the dissipation of uncured consolidation sealing slurry and bridging sealing layer.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a solidified plugging slurry, a plugging method, and an application for plugging leaks in flowing water layers. This solidified plugging slurry does not accumulate in flowing water; the solidified particles can form a permeable layer that remains in the fractures. After a period of time under the temperature and pressure conditions of the formation, it can solidify to form a solidified material of a certain strength, thereby solving the leakage problem in flowing water layers. However, the solidified material has low strength, making it difficult to drill new wellbores after plugging in the wellbore.

[0006] To overcome the shortcomings of the prior art, the present invention provides the following technical solution:

[0007] A type of solidified sealing slurry for sealing leaks in a flowing water leakage layer comprises the following raw material components by weight: 110-150 parts of solidifying material, 60-100 parts of solidifying particles, 2-3 parts of activator, 2-6 parts of retarder, 0-50 parts of weighting agent, and 100 parts of water.

[0008] Furthermore, the consolidation material comprises blast furnace slag powder; the specific surface area of ​​the blast furnace slag powder is ≥400 m². 2 / kg.

[0009] Furthermore, the solidified particles are underwater solidified particles; the particle size of the solidified particles includes three sizes: 0.6-1.3 mm, 1.3 mm-2.2 mm, and 2.2-3.4 mm.

[0010] Furthermore, the activator includes at least one of sodium hydroxide, potassium hydroxide, and sodium silicate;

[0011] And / or, the retarder is borax or borates;

[0012] And / or, the weighting agent includes at least one of barite, micro-manganese, and iron ore powder.

[0013] In addition, the present invention also provides a method for preparing the solidified sealing slurry for sealing the flowing water leakage layer as described above, comprising adding an activator, a retarder, a solidifying material, solidifying particles and a weighting agent to water in a certain proportion, and stirring evenly to obtain the solidified sealing slurry for sealing the flowing water leakage layer.

[0014] In addition, the present invention also provides a method for sealing a leaking water layer, comprising the following steps:

[0015] S1. Lower the drill rod to a depth of 20m-30m below the leaking layer;

[0016] S2. Configure the above-mentioned solidified sealing grout for sealing the flowing water leakage layer according to the actual working conditions;

[0017] S3. Inject the flowing water-filled, solidified plugging slurry prepared in step S2 into the leaking layer, and shut off the well to prevent leakage.

[0018] S4. Pull out the drill string, wait for it to set, and use a plugging agent while drilling to fill the hole.

[0019] Furthermore, in step S2, the amount of consolidation material is adjusted according to the water outflow rate; when the water outflow rate is ≤2.5m... 3 / h, with 140-150 parts of consolidation material selected; effluent rate is 2.5-5m / h. 3 The concentration of the solidification material is 130-140 parts per hour; the effluent rate is 5-7.5 m / h. 3 / h, with 120-130 parts of consolidation material selected; effluent rate ≥7.5m 3 / h, and 110-120 parts of consolidation material are selected.

[0020] Furthermore, the particle size and dosage of the solidified particles are adjusted according to the leakage rate; when the leakage rate is ≤5m3 / h, the particle size of the consolidated particles is selected as 0.6-1.3mm, and the dosage is 60-70 parts; the leakage rate is 5-10m. 3 / h, the particle size of the consolidated particles is selected as 0.6-1.3mm and 1.3-2.2mm, and the ratio of the two particle sizes is 1:1, with a total dosage of 70-75 parts; the leakage rate is 10-20m. 3 / h, the particle size of the consolidated particles is selected as 0.6-1.3mm and 1.3-2.2mm, and the ratio of the two particle sizes is 1:2, with a total dosage of 75-90 parts; the leakage rate is 20-30m. 3 / h, the particle size of the consolidated particles is selected as 0.6-1.3mm, 1.3-2.2mm and 2.2-3.4mm, and the ratio of the three particle sizes of consolidated particles is 1:2:1, with a total dosage of 90-100 parts; leakage rate ≥30m 3 / h, the particle size of the consolidated particles is selected as 0.6-1.3mm, 1.3-2.2mm and 2.2-3.4mm, and the ratio of the three particle sizes of consolidated particles is 1:1:2, and the total amount is 100 parts.

[0021] Furthermore, adjust the amount of retarder according to the well temperature; when the well temperature is 60-90℃, take 2-3 parts of retarder; when the well temperature is 90-120℃, take 3-6 parts of retarder.

[0022] And / or, adjust the amount of weighting agent according to the drilling fluid density; when the drilling fluid density is ≤1.67 g / cm³ 3 No weighting agent required; drilling fluid density >1.67 g / cm³ 3 Weighting agents need to be added.

[0023] In addition, the present invention also provides the application of the above-described solidified plugging slurry for plugging flowing water leakage layers or the above-described plugging method in oil drilling leakage plugging.

[0024] Compared with the prior art, the technical solution of the present invention has at least the following technical effects:

[0025] (1) The micron-sized and millimeter-sized solidification materials in the consolidation plugging slurry of this invention can be solidified individually or in combination. After the slurry enters the leaking layer, the flowing groundwater will carry away the micron-sized solidification materials; the millimeter-sized solidification particles have high inertia and are easy to get stuck in the cracks, forming a high-permeability layer with certain structural force, reducing the impact of groundwater accumulation and erosion. After the plugging operation, the fine particles in the drilling fluid will further seal and reduce permeability.

[0026] (2) The solidified plugging grout of the present invention does not accumulate in flowing water. The underwater solidified particles can form a permeable layer and remain in the crack. After a period of time under the temperature and pressure environment of the formation, it can solidify and form a solidified material with a certain strength, thereby solving the leakage problem of the flowing water layer.

[0027] (3) The sealing layer formed by the solidified plugging slurry of the present invention under flowing water conditions has a pressure bearing capacity of 8.0-11.5MPa, and the solidified body strength is as low as 1.5-4.1MPa. It is not easy to drill a new wellbore after the plug is left. Attached Figure Description

[0028] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein:

[0029] Figure 1 This is a schematic diagram of an evaluation device for solidified plugging grout under simulated flowing water conditions.

[0030] Explanation of reference numerals in the attached drawings: 1-Simulated crack cavity, 2-First piston container, 3-Second piston container, 4-First shut-off valve, 5-High pressure pump, 6-Water tank, 7-Constant flow pump, 8-Second shut-off valve, 9-Third shut-off valve, 10-First ball valve, 11-Second ball valve, 12-Third ball valve, 13-Fourth shut-off valve, 14-Fifth shut-off valve. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Those skilled in the art should understand that the embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Process parameters not specifically specified in the following embodiments are generally performed under conventional conditions.

[0032] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0033] According to a first aspect of the present invention, a consolidation grout for sealing leaks in a flowing water leakage layer is provided, comprising the following raw material components by weight: 110-150 parts of consolidation material (e.g., 110, 120, 130, 140, 150 parts), 60-100 parts of consolidation particles (e.g., 60, 70, 80, 90, 100 parts), 2-3 parts of activator (e.g., 2, 2.5, 3 parts), 2-6 parts of retarder (e.g., 2, 3, 4, 5, 6 parts), 0-50 parts of weighting agent (e.g., 0, 10, 20, 30, 40, 50 parts), and 100 parts of water.

[0034] In addition to initiating consolidation and sealing in areas with weak water flow, the consolidating material can also suspend millimeter-sized consolidated particles during slurry preparation. This synergistic effect enables slurry preparation and pumping. Once the slurry enters the leaky zone, the flowing groundwater carries away the micron-sized consolidating material. The consolidated particles solidify in channels with strong water flow, forming a high-permeability layer and providing initial sealing. The millimeter-sized particles, with their high inertia, easily become trapped in fractures and bridge, forming a high-permeability layer with structural strength, reducing the pressure and erosion effects of groundwater. After the plugging operation, fine particles in the drilling fluid further seal the leak, reducing permeability.

[0035] It is important to emphasize that this invention proposes a "dredging" + "blocking" approach to consolidation and plugging, along with a two-tiered consolidation slurry of micrometer and millimeter dimensions. "Dredging" refers to the fact that the micrometer-sized consolidation material within the slurry can be carried away by flowing water before solidification. After solidification, the remaining slurry forms a highly permeable layer, allowing flowing groundwater to pass smoothly through the leakage channels before and after solidification, reducing the scouring effect of the slurry on the plugging material. "Blocking" refers to the millimeter-sized consolidation particles within the slurry, which can bridge within the leakage channels. Significant friction is generated between the particles and the formation rock, as well as between the particles themselves. Under water-wetting conditions, the contacting consolidation particles can solidify into a single unit, preventing them from being dispersed by flowing water. Furthermore, the micrometer-sized consolidation material and the millimeter-sized consolidation particles can solidify individually or in combination, forming a tight seal even in channels with weak water flow. This consolidation slurry does not accumulate under flowing water; the consolidation particles form a permeable layer that remains within the cracks. After a period of time under the temperature and pressure conditions of the formation, it solidifies into a solidified material of a certain strength, thereby solving the leakage problem in water-bearing layers. The solidified body has low strength, and it is not easy to drill a new wellbore after the plug is left in the wellbore.

[0036] The weight portions described in this invention mainly include the disclosed numerical range, any value (including integers and decimals) within the disclosed range, or an interval between any two values, or multiple discontinuous intervals. It also includes values ​​or numerical ranges whose effects are expected to be similar to the endpoints of the numerical range, such as 5-10 parts. This does not only include 5, 6, 7, 8, 9, 10 parts, or any interval between any two parts. Other numerical ranges, not listed individually, are all included in this invention. Therefore, this invention also includes sub-ranges of any directly disclosed numerical range or any specific value within that range.

[0037] In the aforementioned solidified sealing slurry for plugging leaks in the flowing water leakage layer, as a preferred embodiment, the solidifying material includes blast furnace slag powder; the specific surface area of ​​the blast furnace slag powder is ≥400m². 2 / kg; When the specific surface area is less than 400, adding less will result in insufficient suspension of the slurry, while adding more will result in high solid content, high slurry density, high consistency, and high pumping risk.

[0038] In the aforementioned consolidation slurry for sealing leaks in flowing water layers, as a preferred embodiment, the consolidating particles are preferably underwater consolidating particles with three particle sizes: 0.6-1.3 mm, 1.3 mm-2.2 mm, and 2.2-3.4 mm. The consolidating particles can be consolidated under water-wetting conditions or mixed with blast furnace slag powder in any proportion. The preferred underwater consolidating particles of this invention are a commercially available chemical sand control agent for oil and gas wells, comprising silicate inorganic particles. Under water-wetting conditions, the particles in contact with each other can form a consolidated body with a certain strength.

[0039] In the above-mentioned solidified sealing grout for sealing the flowing water leakage layer, as a preferred embodiment, the activator includes at least one of sodium hydroxide, potassium hydroxide, and sodium silicate;

[0040] Optionally, the retarder is borax or borate;

[0041] Optionally, the weighting agent includes at least one of barite, micro-manganese, and iron ore powder.

[0042] According to a second aspect of the present invention, a method for preparing a solidified plugging slurry for sealing a flowing water leak layer as described above is provided, comprising adding an activator, a retarder, a solidifying material, solidifying particles and a weighting agent to water in a specific ratio, and then stirring until homogeneous to obtain the solidified plugging slurry for sealing a flowing water leak layer.

[0043] According to a third aspect of the present invention, a method for sealing a flowing water leakage layer is provided, specifically comprising the following steps:

[0044] S1. Lower the drill rod to a depth of 20m-30m below the leaking layer;

[0045] S2. Configure the above-mentioned solidified sealing grout for sealing the flowing water leakage layer according to the actual working conditions;

[0046] S3. Inject the flowing water-filled, solidified plugging slurry prepared in step S2 into the leaking layer, and shut off the well to prevent leakage.

[0047] S4. Pull out the drill string, wait for it to set, and then plug the hole with the drilling fluid containing lost circulation material. The drilling fluid containing lost circulation material here is a conventional drilling fluid containing lost circulation material in the field. It can be a commercially available product or a self-prepared one. In this invention, it is preferred to prepare the drilling fluid with 3% sawdust and 2% plant fiber.

[0048] It should be noted that there is no fixed standard for the injection volume of solidified plugging grout for plugging leaks in flowing water leakage layers. In actual operation, it is generally injected to fill the volume of 200-300m of open hole wellbore, and the total grout volume is increased by 5-6m based on the injection volume. 3 The slurry is pumped by a large mud pump, typically with a discharge rate in the range of 10L / s to 30L / s.

[0049] Actual operating parameters include water production rate, drilling fluid leakage rate, well temperature, and drilling fluid density; among which, water production rate (water production rate at the wellhead) and leakage rate refer to the amount of reduction in drilling fluid volume measured after circulating the drilling fluid at a certain discharge rate for a period of time, thereby determining the drilling fluid leakage rate.

[0050] In the above-described leak-sealing method, as a preferred embodiment, in step S2, the amount of solidification material is adjusted according to the water outflow rate; when the water outflow rate is ≤2.5m... 3 / h, with 140-150 parts of consolidation material selected; effluent rate is 2.5-5m / h. 3 The concentration of the solidification material is 130-140 parts per hour; the effluent rate is 5-7.5 m / h. 3 / h, with 120-130 parts of consolidation material selected; effluent rate ≥7.5m 3 For a flow rate of 110-120 parts per hour, the solidification material should be selected. The higher the outflow rate, the stronger the flushing effect of the flowing water. Therefore, the amount of micron-sized solidification material should be reduced and the amount of millimeter-sized solidification particles should be increased. This makes the slurry thinner, the solidification material easier to lose, the weaker the carrying effect on millimeter-sized solidification particles, and the higher the permeable layer of the solidified body. This is conducive to the passage of flowing water and the retention of millimeter-sized solidification particles.

[0051] In the above-mentioned leak-sealing method, as a preferred embodiment, the particle size and dosage of the solidified particles are adjusted according to the leakage rate; when the leakage rate is ≤5m... 3 / h, the particle size of the consolidated particles is selected as 0.6-1.3mm, and the dosage is 60-70 parts; the leakage rate is 5-10m. 3 / h, the particle size of the consolidated particles is selected as 0.6-1.3mm and 1.3-2.2mm, and the total amount of consolidated particles is 70-75 parts, with the weight ratio of the two particle sizes being 1:1; the leakage rate is 10-20m. 3 / h, the particle size of the consolidated particles is selected as 0.6-1.3mm and 1.3-2.2mm, and the ratio of the two particle sizes is 1:2. The total amount of consolidated particles is 75-90 parts; the leakage rate is 20-30m. 3 / h, the particle size of the consolidated particles is selected as 0.6-1.3mm, 1.3-2.2mm and 2.2-3.4mm, and the ratio of the three particle sizes is 1:2:1. The total amount of consolidated particles is 90-100 parts; the leakage rate is ≥30m 3 / h, the particle size of the consolidated particles is selected as 0.6-1.3mm, 1.3-2.2mm and 2.2-3.4mm, the ratio of the three particle sizes of consolidated particles is 1:1:2, and the total amount of consolidated particles is 100 parts.

[0052] In the above-mentioned plugging method, as a preferred embodiment, the dosage of retarder is adjusted according to the well temperature; when the well temperature is 60-90℃, the dosage of retarder is 2-3 parts; when the well temperature is 90-120℃, the dosage of retarder is 3-6 parts.

[0053] Optionally, the amount of weighting agent can be adjusted according to the drilling fluid density; when the drilling fluid density is ≤1.67 g / cm³ 3 No weighting agent required; drilling fluid density >1.67 g / cm³ 3 Weighting agents need to be added. If the formation contains a high-pressure layer with a formation pressure density equivalent greater than 1.67 g / cm³, then weighting agents are required. 3 When plugging leaks, well control risks need to be considered, and weighting agents need to be added to balance formation pressure.

[0054] According to a fourth aspect of the invention, the application of the solidified plugging slurry for plugging the flowing water leakage layer as described above or the plugging method described above in oil drilling leakage plugging is provided.

[0055] To test the performance of the solidified plugging grout for sealing leaks in flowing water layers according to the present invention, an evaluation device for the solidified plugging grout under simulated flowing water conditions was prepared (as shown in the attached document). Figure 1 (As shown); The evaluation device specifically includes: simulated crack cavity 1, first piston container 2, second piston container 3, high pressure pump 5, constant flow pump 7, water tank 6, second shut-off valve 8, third shut-off valve 9, first ball valve 10, second ball valve 11, third ball valve 12, fourth shut-off valve 13, fifth shut-off valve 14 and other components. The simulated crack cavity 1 is equipped with a simulated crack module and a rubber sleeve inside, and is equipped with heat preservation and heating components on the outside.

[0056] The simulated crack module has multiple holes, on which pipelines, seals, and a second shut-off valve 8 are installed and connected to a constant flow pump 7. The constant flow pump 7 can inject simulated groundwater from the slurry tank 6 into the simulated crack module to simulate groundwater intrusion.

[0057] The rubber sleeve can isolate the simulated crack cavity 1 and the simulated crack module, and is used to seal the simulated crack module.

[0058] The simulated crack cavity has two openings at the bottom and top, respectively, which are connected to the first shut-off valve 4 and the third shut-off valve 9.

[0059] The simulated crack cavity 1 has an inlet and an outlet at both ends. The inlet and outlet are connected to the internal simulated crack module. The outlet is connected to the first ball valve 10, and the inlet is divided into two branches. The first branch is connected to the third ball valve 12 and the first piston container 2 in sequence, and the second branch is connected to the second ball valve 11 and the second piston container 3 in sequence.

[0060] The high-pressure pump 5 has three outlet branches: the first branch is connected to the fourth shut-off valve 13 and the second piston container 3; the second branch is connected to the fifth shut-off valve 14 and the first piston container 2; and the third branch is connected to the first shut-off valve 4. The high-pressure pump 5 inlet is connected to the water tank 6.

[0061] The following details the specific evaluation methods of the self-made evaluation device:

[0062] (1) Select a simulated crack module with appropriate opening, length and width according to the evaluation requirements, and install it in the simulated crack cavity 1. Open the upper cover of the first piston container 2 and the second piston container 3, push the piston to the bottom of the container, pour in the pre-prepared consolidation grout and pressure grout respectively, and tighten the upper cover.

[0063] (2) Open the first shut-off valve 4 and the third shut-off valve 9, turn on the high-pressure pump 5, observe the outlet of the third shut-off valve 9, and close the third shut-off valve 9 when water flows out of the outlet. Observe the pressure value of the high-pressure pump, and close the first shut-off valve 4 and the high-pressure pump 5 after setting a lower confining pressure.

[0064] (3) Open the heating component outside the simulated crack cavity 1, set the temperature according to the test requirements, and after the temperature stabilizes, open the high pressure pump 5 and the first shut-off valve 4, observe the pressure value of the high pressure pump, and close the first shut-off valve 4 and the high pressure pump 5 after the pressure value meets the requirements.

[0065] (4) Open the first ball valve 10, fill the water tank 6 with clean water, open the second shut-off valve 8, set the flow rate on the constant flow pump 7 and turn on the constant flow pump 7. When clean water flows out of the first ball valve 10, adjust the flow rate of the constant flow pump 7 to simulate groundwater flowing into the crack.

[0066] (5) Open the third ball valve 12 and the fifth shut-off valve 14, set the flow rate of the high-pressure pump 5 according to the test requirements, and start the high-pressure pump 5. The consolidation and plugging grout is injected into the simulated crack from the first piston container 2. After observing that the consolidation grout flows out of the outlet of the first ball valve 10, close the third ball valve 12, the fifth shut-off valve 14 and the high-pressure pump 5.

[0067] (6) The simulated fracture cavity 1 is continuously heated until the solidification slurry inside the simulated fracture module is completely solidified, then the second shut-off valve 8 and the constant flow pump 7 are closed.

[0068] (7) Clean the consolidation and plugging grout at the inlet of the simulated fracture cavity 1 and the pipeline, open the second ball valve 11 and the fourth shut-off valve 13, adjust the flow rate of the high-pressure pump 5 and start the high-pressure pump, and record the highest pressure at the inlet of the simulated fracture cavity 1. This pressure value is the pressure bearing capacity.

[0069] The present invention will now be described in detail with reference to embodiments thereof. These examples are provided by way of explanation and not by way of limitation. In fact, those skilled in the art will recognize that modifications and variations can be made to the present invention without departing from its scope or spirit. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desirable that the present invention encompass such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0070] In the embodiments of the present invention, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0071] Example 1

[0072] This embodiment provides a method for sealing leaks in a flowing water leakage layer:

[0073] A well, with a second-stage borehole diameter of 215.9 mm and a surface casing shoe depth of 860 m, experienced drilling loss at a flow rate of 50 L / s to 1808 m. The lithology is sandstone, and the drilling fluid density is 1.28 g / cm³. 3 One hour after the pump was stopped, the drilling fluid volume increased by 6.8 m³. 3 The leaking layer was determined to contain flowing water. The measured well depth was 1808m and the well temperature was 76℃. The plugging method of this invention was used for consolidation plugging. The specific steps are as follows:

[0074] (1) Lower the drill rod to 1782m;

[0075] (2) Circulating the drilling fluid at a displacement of 50 L / s for 15 minutes, it was found that the drilling fluid volume decreased by 6.1 m³. 3 The drilling fluid loss rate was determined to be 24.4 m. 3 / h;

[0076] (3) Rinse the mud tank with clean water;

[0077] (4) Based on the leakage rate of 24.4m 3 / h, water output rate 6.8m 3 / h, well temperature 76℃, drilling fluid density 1.28g / cm³ 3 Parameters, based on 16m of clean water 3 20t of blast furnace slag powder, 4t of 0.6-1.3mm underwater solidified particles, 8t of 1.3-2.2mm underwater solidified particles, 4t of 2.2-3.4mm underwater solidified particles, 0.32t of sodium hydroxide and 0.32t of boric acid are mixed in a mud tank to prepare a solidification and plugging slurry.

[0078] (5) Shut down the well and inject consolidation and plugging grout into the leaking layer at a flow rate of 50 L / s for 10 m. 3 Then, reduce the displacement to 20L / s and inject 5m. 3 Pull the drill string into the casing and shut the well in for 24 hours to allow it to solidify.

[0079] (6) When pulling out the drill string, add 3% sawdust and 2% plant fiber to the drilling fluid and then run the probe plug down.

[0080] (7) Drilling down to 1753m encountered a blockage, and drilling the blockage down to 1808m, with no leakage, the leak was successfully plugged.

[0081] Example 2

[0082] This embodiment provides a method for sealing leaks in a flowing water leakage layer:

[0083] In a certain well, with a three-stage wellbore diameter of 152.4 mm and a technical casing shoe depth of 2400 m, drilling fluid loss occurred at a depth of 2723 m. The lithology is sandstone, and the drilling fluid density is 1.58 g / cm³. 3 With a drilling flow rate of 31 L / s, the drilling fluid volume increased by 3.8 m³ / s one hour after the pump was stopped. 3 The leaking layer was determined to contain flowing water. The measured well depth was 2723m and the well temperature was 104℃. The plugging method of this invention was used for consolidation plugging. The specific steps are as follows:

[0084] (1) Lower the drill rod to 2700m;

[0085] (2) Circulating the drilling fluid at a displacement of 31 L / s for 15 minutes, it was found that the drilling fluid volume decreased by 2.8 m³. 3 The drilling fluid loss rate was determined to be 11.2 m. 3 / h;

[0086] (3) Rinse the mud tank with clean water;

[0087] (4) Based on the leakage rate of 11.2m 3 / h, water output rate 3.8m3 / h, well temperature 104℃, drilling fluid density 1.58g / cm³ 3 Parameters, based on 10m of clean water 3 14t of blast furnace slag powder, 2.5t of 0.6-1.3mm solidified particles, 5t of 1.3-2.2mm solidified particles, 0.2t of sodium hydroxide and 0.4t of boric acid were mixed in a mud tank to prepare a solidified plugging slurry.

[0088] (5) Shut down the well and inject consolidation and plugging grout into the leaking layer at a rate of 31 L / s for 4 m. 3 Then, reduce the displacement to 15L / s and inject 5m. 3 Drilling was completed to the casing, and the well was shut in for 16 hours to allow the material to solidify.

[0089] (6) When pulling out the drill string, add 3% sawdust and 2% plant fiber to the drilling fluid and then run the probe plug down.

[0090] (7) The drilling reached 2683m and encountered a blockage. The blockage was drilled to 2723m without leakage, and the leak was successfully plugged.

[0091] Example 3

[0092] This embodiment provides a solidified sealing grout for sealing leaks in flowing water leakage layers. The raw material components and preparation method are as follows:

[0093] Take 1000mL of clean water, add 30g of sodium hydroxide and 60g of borax and dissolve them completely. Then add 1300g of blast furnace slag powder and stir evenly. Add 1000g of underwater solidification particles (particle size 0.6-1.3mm) to the slurry and stir evenly to prepare the solidification and plugging slurry of this embodiment.

[0094] The uniaxial compressive strength of the consolidated slurry was evaluated as 4.1 MPa, the thickening time of the slurry at 40 MPa and 120℃ was 354 min, and the pressure resistance of the slurry for plugging leaks at 120℃ under flowing water conditions was 11.5 MPa.

[0095] Example 4

[0096] This embodiment provides a solidified sealing grout for sealing leaks in flowing water leakage layers. The raw material components and preparation method are as follows:

[0097] Take 1000mL of clean water, add 20g of sodium hydroxide and 40g of borax and dissolve them completely. Then add 1300g of blast furnace slag powder and stir evenly. Add 1000g of underwater solidification particles (particle size 0.6-1.3mm) to the slurry and stir evenly to prepare the solidification and plugging slurry of this embodiment.

[0098] The uniaxial compressive strength of the consolidated slurry was evaluated as 3.8 MPa, the thickening time was 265 min under conditions of 30 MPa and 110℃, and the pressure resistance of the consolidated slurry for plugging leaks was 9.8 MPa under conditions of 110℃ and flowing water.

[0099] Example 5

[0100] This embodiment provides a solidified sealing grout for sealing leaks in flowing water leakage layers. The raw material components and preparation method are as follows:

[0101] Take 1000mL of clean water, add 25g of sodium hydroxide and 30g of borax and dissolve them completely. Then add 1200g of blast furnace slag powder and stir evenly. Add 800g of underwater solidification particles (particle size 0.6-1.3mm) to the slurry and stir evenly to prepare the solidification and plugging slurry of this embodiment.

[0102] The uniaxial compressive strength of the consolidated slurry was evaluated at 3.5 MPa, the slurry strength was 20 MPa, the thickening time was 186 min at 90℃, and the slurry pressure resistance for plugging leaks was 10.3 MPa under flowing water conditions at 90℃.

[0103] Example 6

[0104] This embodiment provides a solidified sealing grout for sealing leaks in flowing water leakage layers. The raw material components and preparation method are as follows:

[0105] Take 1000mL of clean water, add 25g of sodium hydroxide and 30g of borax and dissolve them completely. Then add 1500g of blast furnace slag powder and stir evenly. Add 600g of underwater solidification particles (particle size 0.6-1.3mm) to the slurry and stir evenly to prepare the solidification and plugging slurry of this embodiment.

[0106] The uniaxial compressive strength of the consolidated slurry was 3.2 MPa, the thickening time of the slurry at 70℃ was 204 min, and the pressure resistance of the slurry for plugging leaks under flowing water conditions at 70℃ was 8 MPa.

[0107] Example 7

[0108] Take 1000mL of clean water, add 20g of sodium hydroxide and 20g of borax and dissolve them completely. Then add 1100g of blast furnace slag powder and stir evenly. Add 1000g of underwater solidification particles (particle size 0.6-1.3mm) to the slurry and stir evenly to prepare the solidification and plugging slurry of this embodiment.

[0109] The uniaxial compressive strength of the consolidated slurry was 1.5 MPa, the thickening time of the slurry at 60℃ was 121 min, and the pressure resistance of the slurry for plugging leaks under flowing water conditions at 60℃ was 8.3 MPa.

[0110] Comparative Example 1

[0111] This comparative example is prepared according to Example 3, using a solidified plugging slurry for sealing the flowing water leakage layer, the only difference being that no solidification particles were added.

[0112] The uniaxial compressive strength of the solidified slurry was evaluated as 4.5 MPa. The thickening time of the solidified slurry under 40 MPa and 120℃ conditions was 432 min. However, the pressure resistance of the solidified slurry for plugging leaks under flowing water conditions at 120℃ was 0 MPa. No sealing layer was found when the crack module was disassembled, and the solidified material was carried away by the flowing water.

[0113] Comparative Example 2

[0114] This comparative example was prepared according to Example 3, using a solidified sealing slurry for sealing leaks in a flowing water leakage layer. The only difference was that no solidifying material was added. It was found that the solidified particles in the slurry settled rapidly during the preparation process, making it inconvenient for on-site sealing operations.

[0115] Comparative Example 3

[0116] This comparative example is prepared according to Example 3, using a solidified sealing slurry for sealing the flowing water leakage layer. The only difference is that the amount of solidified particles added is 500g (i.e., 50 parts).

[0117] The uniaxial compressive strength of the consolidated slurry was evaluated as 0 MPa, indicating that the slurry could not form a consolidated body with sufficient strength and thus failed to achieve the desired performance.

[0118] Comparative Example 4

[0119] This comparative example is prepared according to Example 3, using a solidified sealing slurry for sealing the flowing water leakage layer. The only difference is that the amount of solidifying material added is 900g (i.e., 90 parts).

[0120] It was found that during the preparation of the slurry, the solidified particles settled rapidly, and a small amount of clear water was separated from the upper layer. The slurry had poor suspension stability and was not convenient for on-site leak sealing operations.

[0121] Experimental Example 1

[0122] The solidified plugging slurry for plugging leaks in flowing water prepared in Examples 3-6 and Comparative Example 1 were subjected to performance tests (including uniaxial compressive strength, thickening time under different temperature conditions, and plugging capacity under flowing water conditions) using the self-made evaluation device for solidified plugging slurry under simulated flowing water conditions.

[0123] The test methods for the leak-stopping capacity under different temperature flowing water conditions are as follows:

[0124] 1. Take 1000mL of clean water, add 3g of sodium carbonate and wait until it is fully dissolved, then add 60g of bentonite and stir to hydrate for 24 hours to prepare a pressure-bearing grout.

[0125] 2. Select a simulated crack module with an opening of 3mm, a length of 1000mm, and a width of 50mm and install it inside the simulated crack cavity. Open the upper caps of the first and second piston containers, push the pistons to the bottom of the containers, pour in the consolidation grout and the pressure grout respectively, and tighten the upper caps.

[0126] 3. Open the first and third shut-off valves, turn on the high-pressure pump, and observe the outlet of the third shut-off valve. Close the third shut-off valve when water flows out of the outlet. Observe the pressure value of the high-pressure pump. After the pressure value reaches 2MPa, close the first shut-off valve and the high-pressure pump.

[0127] 4. Turn on the heating components outside the simulated crack cavity and set the temperature to 120℃. After the temperature stabilizes, turn on the high-pressure pump and the first shut-off valve, observe the pressure value of the high-pressure pump, and turn off the first shut-off valve and the high-pressure pump after the pressure value reaches 30MPa.

[0128] 5. Open the first ball valve, fill the water tank with clean water, open the second shut-off valve, set the flow rate of the constant flow pump to 50 mL / min, and turn on the cross-flow pump. When clean water flows out of the first ball valve, adjust the flow rate of the constant flow pump to 0.5 mL / min to simulate groundwater flowing into the crack.

[0129] 6. Open the third ball valve and the fifth shut-off valve, set the high-pressure pump flow rate to 30 mL / min and start the high-pressure pump. Inject the consolidation slurry into the simulated crack from the first piston container. After observing a uniform flow of consolidation slurry from the outlet of the first ball valve, close the third ball valve, the fifth shut-off valve and the high-pressure pump.

[0130] 7. After the simulated fracture cavity has been continuously heated for 24 hours, the consolidation slurry inside the simulated fracture module has completely solidified, and the second shut-off valve and constant flow pump are then turned off.

[0131] 8. Clean the consolidation material at the entrance of the simulated fracture cavity and the pipeline, open the second ball valve and the fourth shut-off valve, adjust the high-pressure pump flow rate to 5 mL / min and turn on the high-pressure pump, and record the highest pressure at the entrance of the simulated fracture cavity. This pressure value is the pressure-bearing capacity.

[0132] The test results are shown in Table 1:

[0133] Table 1

[0134]

[0135]

[0136] As shown in Table 1, the solidified plugging slurry prepared using the technical solution of this invention exhibits a compressive strength of 1.5-4.1 MPa after solidification, with an adjustable thickening time of 91-354 min, and a pressure-bearing capacity of 8-11.5 MPa under flowing water conditions. The prepared solidified plugging slurry does not accumulate in flowing water; the underwater solidified particles can form a permeable layer that remains in the fracture. After a period of time under the temperature and pressure conditions of the formation, it can solidify into a solidified material of a certain strength, thereby solving the leakage problem in water-bearing layers. However, the solidified body has low strength, making it difficult to drill new wellbores after plugging in the wellbore.

[0137] The foregoing has described and evaluated some embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. This does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, still fall within the protection scope of the present invention.

Claims

1. A consolidation grout for sealing leaks in flowing water leakage layers, characterized in that, By weight, it includes the following raw material components: 110-150 parts of consolidating material, 60-100 parts of consolidating particles, 2-3 parts of activator, 2-6 parts of retarder, 0-50 parts of weighting agent, and 100 parts of water.

2. The solidified sealing grout for sealing leaks in a flowing water leakage layer according to claim 1, characterized in that, The consolidation material includes blast furnace slag powder; the specific surface area of ​​the blast furnace slag powder is ≥400m². 2 / kg.

3. The solidified sealing grout for sealing leaks in a flowing water leakage layer according to claim 1, characterized in that, The solidified particles are underwater solidified particles; the particle size of the solidified particles includes three sizes: 0.6-1.3 mm, 1.3 mm-2.2 mm, and 2.2-3.4 mm.

4. The solidified sealing grout for sealing leaks in flowing water leakage layers according to any one of claims 1-3, characterized in that, The activator includes at least one of sodium hydroxide, potassium hydroxide, and sodium silicate; And / or, the retarder is borax or borate; And / or, the weighting agent includes at least one of barite, micro-manganese, and iron ore powder.

5. A method for preparing a solidified sealing grout for sealing a flowing water leakage layer as described in any one of claims 1-4, characterized in that, The process involves adding an activator, a retarder, a solidifying material, solidifying particles, and a weighting agent to water in a specific ratio, followed by thorough mixing to obtain the solidified sealing slurry for plugging the flowing water leakage layer.

6. A method for sealing leaks in a flowing water leakage layer, characterized in that, Includes the following steps: S1. Lower the drill rod to a depth of 20m-30m below the leaking layer; S2. Configure the solidified sealing grout for sealing the flowing water leakage layer as described in any one of claims 1-4 according to the actual working conditions; S3. Inject the flowing water-filled, solidified plugging slurry prepared in step S2 into the leaking layer, and shut off the well to prevent leakage. S4. Pull out the drill string, wait for it to solidify, and use a plugging agent while drilling to fill the hole.

7. The leak-sealing method according to claim 6, characterized in that, In step S2, the amount of consolidation material is adjusted according to the water outflow rate; when the water outflow rate is ≤2.5m... 3 / h, with 140-150 parts of consolidation material selected; effluent rate is 2.5-5m / h. 3 / h, with 130-140 parts of consolidation material selected; effluent rate is 5-7.5m / h. 3 / h, with 120-130 parts of consolidation material selected; effluent rate ≥7.5m 3 / h, and 110-120 parts of consolidation material are selected.

8. The leak-sealing method according to claim 6, characterized in that, Adjust the particle size and dosage of the solidified particles according to the leakage rate; when the leakage rate is ≤5m 3 / h, the particle size of the consolidated particles is selected as 0.6-1.3mm, and the dosage is 60-70 parts; the leakage rate is 5-10m. 3 / h, the particle size of the consolidated particles is selected as 0.6-1.3mm and 1.3-2.2mm, and the ratio of the two particle sizes is 1:1, with a total dosage of 70-75 parts; the leakage rate is 10-20m. 3 / h, the particle size of the consolidated particles is selected as 0.6-1.3mm and 1.3-2.2mm, and the ratio of the two particle sizes is 1:2, with a total dosage of 75-90 parts; the leakage rate is 20-30m. 3 / h, the particle size of the consolidated particles is selected as 0.6-1.3mm, 1.3-2.2mm and 2.2-3.4mm, and the ratio of the three particle sizes of consolidated particles is 1:2:1, with a total dosage of 90-100 parts; leakage rate ≥30m 3 / h, the particle size of the consolidated particles is selected as 0.6-1.3mm, 1.3-2.2mm and 2.2-3.4mm, and the ratio of the three particle sizes of consolidated particles is 1:1:2, and the total amount is 100 parts.

9. The leak-sealing method according to claim 6, characterized in that, Adjust the amount of retarder according to the well temperature; when the well temperature is 60-90℃, take 2-3 parts of retarder; when the well temperature is 90-120℃, take 3-6 parts of retarder. And / or, adjust the amount of weighting agent according to the drilling fluid density; when the drilling fluid density is ≤1.67 g / cm³ 3 No weighting agent required; drilling fluid density >1.67 g / cm³ 3 Weighting agents need to be added.

10. The application of the solidified plugging slurry for plugging flowing water leakage layers as described in any one of claims 1-4 and / or the plugging method as described in any one of claims 6-9 in oil well plugging.

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