Solid-phase sintering treatment method for waste oil-based drilling fluid, sintered material and application

Abstract

The invention belongs to the technical field of oilfield exploitation, and particularly relates to a waste oil-based drilling fluid solid-phase sintering treatment method, a sintered material and application. The solid phase sintering treatment method for the waste oil-based drilling fluid comprises the following steps: (1) performing thermal desorption on the waste oil-based drilling fluid, and grinding to obtain a thermal desorption solid phase; (2) collecting the thermal desorption solid-phase sample, carrying out heat treatment, and measuring the element content; (3) adding an admixture into the thermal desorption solid phase according to the element content to obtain a mixture; and (4) calcining, cooling and grinding the mixture to obtain a sintered material. According to the invention, thermal desorption solid phases generated under different well conditions are treated into an admixture with controllable performance, and meanwhile, the well cementation cement slurry constructed by using the admixture has good performance and meets the requirements of well cementation operation, so that in-situ treatment of hazardous wastes is achieved, the discharge amount is reduced, and the treatment cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of oilfield development technology, specifically relating to a method for solid-phase sintering treatment of waste oil-based drilling fluid, as well as the sintering material and its application. Background Technology

[0002] Oil-based drilling fluids are drilling fluids with oil as the continuous phase. By adding emulsifiers, stabilizers, and filtration reducers, they acquire superior properties. Compared to water-based drilling fluids, oil-based drilling fluids have better lubrication, inhibition, and thermal stability, and have found good applications in deep wells, ultra-deep wells, and complex formations prone to water collapse. However, with the increasing number of times oil-based drilling mud is recycled, fine drill cuttings continuously infiltrate, causing its performance to gradually deteriorate and rendering it unusable, resulting in waste oil-based drilling fluid. According to GB4914-2008 "Limits for Pollutant Discharge Concentrations in Marine Oil Exploration and Development," oil-based drilling fluids must not be discharged into the sea and require further treatment.

[0003] Currently, the main methods for treating waste oil-based drilling mud include thermal distillation desorption (thermal desorption), solvent extraction, supercritical fluid extraction, in-pit sealing and burial, injection into safe formations, and chemical demulsification. Among these, thermal desorption is a conventional large-scale treatment method, with processing temperatures ranging from 260℃ to 500℃ and a high oil recovery rate, exceeding 90%. During thermal distillation desorption, the recovered oil is generally reformulated into oil-based drilling mud for reuse. However, the residual thermal desorption solids still contain certain oily substances. According to the "National Hazardous Waste List - 2016," waste oil-based drilling fluid thermal desorption solids are still classified as hazardous waste and require further treatment.

[0004] Waste oil-based mud desorbed solids are mainly treated through landfilling, road paving, and cement production. Landfilling is the most common method, but because the desorbed solids still contain a large amount of harmful substances, these substances can seep into the soil and pollute groundwater. In road paving, the desorbed solids are mainly used as paving material by introducing a curing agent, but over time, harmful substances in the solids will gradually migrate out, causing secondary pollution. Cement production can remove organic matter from the solids, but the process is energy-intensive, and the presence of large amounts of chloride ions and barite in the solids can adversely affect cement materials. Therefore, special treatment is generally required, and the solids should be used in separate pipelines.

[0005] The use of waste oil-based drilling fluid thermally desorbed dry residue in cementing slurry has not yet been implemented. However, similar research on the application of oil-based drilling mud cuttings mainly involves adding the residue after thermal distillation of drilling cuttings as an admixture to the cement slurry to achieve cementing purposes. However, waste oil-based drilling mud and waste oil-based drilling mud cuttings differ significantly in composition, particularly in inorganic salt content, cuttings content, and residual oil content. Due to its complex composition and hydrophobic surface, direct use of waste oil-based drilling mud thermally desorbed dry residue in the preparation of cementing slurry can easily lead to adverse consequences such as slow mixing speed, poor rheological properties, and strength loss, failing to meet the requirements of cementing operations. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for solid-phase sintering treatment of waste oil-based drilling fluid, as well as the sintering material and its application.

[0007] Specifically, the waste oil-based drilling fluid solid-phase sintering treatment method provided by the present invention includes: (1) Thermal desorption of waste oil-based drilling fluid was performed, and the resulting solid phase was obtained by grinding. (2) Collect the thermally desorbed solid sample, and determine its elemental content after heat treatment; (3) Add external admixtures to the thermally desorbed solid phase according to the element content to obtain a mixture; (4) The mixture is calcined, cooled and ground to obtain sintered material.

[0008] In the above-mentioned waste oil-based drilling fluid solid phase sintering treatment method, the thermal desorption temperature is 260℃~500℃.

[0009] In the above-mentioned waste oil-based drilling fluid solid phase sintering treatment method, the oil content of the thermally desorbed solid phase is ≤3wt%, and the particle size is ≤150μm.

[0010] The aforementioned waste oil-based drilling fluid solid-phase sintering treatment method includes, as mentioned above, one or more of barite, calcium oxide, bauxite, quartz, and calcium chloride as admixtures.

[0011] In the above-mentioned waste oil-based drilling fluid solid phase sintering treatment method, the external admixtures, based on the mass percentage of the thermally desorbed solid phase, include: barite 0~25.0%, calcium oxide 0~15.0%, bauxite 0~7.5%, quartz 0~18.0%, and calcium chloride 0~6.5%.

[0012] In the above-mentioned solid-phase sintering treatment method for waste oil-based drilling fluid, the calcination temperature is 1300~1500℃ and the duration is 0.5~2.5h.

[0013] The sintering material provided by this invention is prepared using the above-mentioned waste oil-based drilling fluid solid-phase sintering treatment method.

[0014] The above-mentioned sintering materials, by weight percentage, include: SiO2 31.0%~34.5%, Al2O3 12.5%~15.5%, CaO 18.5%~22.8%, Cl 4.8%~5.6%, BaO 16.5%~18.5%, SO3 8.5%~9.5%, and other components 2%~5%.

[0015] The cement slurry provided by the present invention includes the above-mentioned sintered material.

[0016] The present invention also provides the application of the above-mentioned sintered material in the preparation of cementing slurry.

[0017] The technical solution of the present invention has the following beneficial effects: (1) The waste oil-based drilling fluid solid phase sintering treatment method of the present invention treats the thermally desorbed solid phase generated under different well conditions into an admixture with controllable performance. At the same time, the cementing slurry constructed using the above admixture has good performance and meets the cementing operation requirements, thereby achieving in-situ disposal of hazardous waste, reducing emissions and lowering treatment costs. (2) The waste oil-based drilling fluid solid phase sintering treatment method of the present invention produces a single product within the solid phase range, with good consistency, effectively avoiding the pollution of cement slurry by residual oil and the adverse effects on cement slurry ash runoff. (3) The sintered material obtained according to the method of the present invention can replace part of the cement and, together with other additives, can form a stable cement slurry system with a cement slurry density of up to 1.60 g / cm³. 3 ~1.90g / cm 3 ; (4) The sintering material obtained according to the method of the present invention has good properties in the preparation of cement slurry, and the strength can reach more than 14 MPa, which can meet the cementing requirements; the strength of low density cement slurry can reach more than 3.5 MPa, and it can be used as low density filling slurry. Detailed Implementation

[0018] To fully understand the purpose, features, and effects of this invention, the following detailed embodiments are provided. Except as described below, the process methods of this invention employ conventional methods or apparatus in the art. Unless otherwise specified, the terms and expressions used below have the meanings commonly understood by those skilled in the art.

[0019] When a range of values ​​is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0020] This invention focuses on the further harmless and resource-oriented treatment of the solid phase of thermal desorption of waste oil-based drilling fluid.

[0021] After thermal desorption treatment, the dry residue in the desorbed solid phase of waste oil-based drilling fluid mainly contains barite powder, broken drill cuttings, and other substances. Additionally, the solid particles adsorb approximately 0.8% to 2% mineral oil and a small amount of surfactant. The content and types of barite powder and drill cuttings in the solid phase vary depending on the drilling process and the drilling depth within the same well. Furthermore, the adsorbed organic matter contributes to the strong hydrophobicity of the solid phase. Directly using this as an admixture in cementing slurry would have significant adverse effects, hindering large-scale application.

[0022] Based on this, the present invention provides a method for solid-phase sintering treatment of waste oil-based drilling fluid, comprising: (1) Thermal desorption of waste oil-based drilling fluid was performed, and the resulting solid phase was obtained by grinding. (2) Collect the thermally desorbed solid sample, and determine its elemental content after heat treatment; (3) Add external admixtures to the thermally desorbed solid phase according to the element content to obtain a mixture; (4) The mixture is calcined, cooled and ground to obtain sintered material.

[0023] The waste oil-based drilling fluid solid phase sintering treatment method of the present invention involves detecting the composition of the thermally desorbed solid phase, adding admixtures according to the detection results, and then calcining it to process the thermally desorbed solid phase generated under different well conditions into a sintered material with controllable performance. The cement slurry constructed using the sintered material of the present invention has good performance and meets the requirements of cementing operations, thereby achieving in-situ disposal of hazardous waste, reducing emissions, and lowering treatment costs.

[0024] In some preferred embodiments, waste oil-based drilling fluid is thermally desorbed at 260°C to 500°C to obtain a thermally desorbed solid phase with an oil content of ≤3wt%.

[0025] To obtain a sintered material with uniform composition, it is preferable to grind the thermally desorbed solid phase to obtain powder with a particle size ≤150μm (100 mesh sieve).

[0026] In some optional embodiments, when determining the composition of the thermally desorbed solid sample after heat treatment at 1000~1200°C, the content of each element is expressed as oxides.

[0027] In some preferred embodiments, the external admixtures include: quartz, bauxite, calcium oxide, calcium chloride, and barite. The particle size of each component of the external admixture is ≤150 μm (100 mesh sieve).

[0028] This invention modifies the composition of the solid phase of waste oil-based drilling fluid by using external additives such as barite and quartz, and then calcines it at high temperature to form a high-temperature sintered material with good performance.

[0029] In some preferred embodiments, the mixture is calcined at 1300~1500℃ for 0.5~2.5h (preferably 2h), naturally cooled, ground, and sieved to obtain a sintered material, the main components of which contain 31.0%~34.5% SiO2, 12.5%~15.5% Al2O3, 18.5%~22.8% CaO, 4.8~5.6% Cl, 16.5%~18.5% BaO, 8.5%~9.5% SO3, and 2%~5% of other components.

[0030] Through practice, the sintered material obtained by this invention can replace part of the cement and, together with other additives, can form a stable cementing slurry system. The density of the cementing slurry system can be between 1.60 g / cm³ and 1.90 g / cm³, and the strength can reach more than 14 MPa, which meets the cementing requirements.

[0031] Example The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments, unless otherwise specified, were performed according to conventional methods and conditions. The raw materials used in the following embodiments were all commercially available.

[0032] Example 1 Waste oil-based drilling fluid from a certain block of CNOOC in Wenchang was thermally desorbed at 400℃. After grinding and sieving, the particle size of the thermally desorbed dry residue was 150μm (100 mesh sieve) and the oil content was 0.9wt.%, thus obtaining the preliminary thermally desorbed solid phase.

[0033] The thermally desorbed solid sample was collected and heated at 1200℃. The contents of the main components were then determined. Based on the oxide content, the contents were: SiO2 29.1%, Al2O3 20.1%, CaO 14.3%, Cl 1.6%, BaO 19.9%, SO3 10.4%, and other components 4.6%.

[0034] Take 100g of the sample after heat treatment at 1200℃ and add the following admixtures: 12.2g quartz, 0g bauxite, 10.5g calcium oxide, 3.6g barite, and 5.5g calcium chloride. The particle size of the sample and each admixture is 150μm (100-mesh sieve), and the corrected mixture is obtained.

[0035] The modified mixture was calcined at 1450℃ for 2 hours, then naturally cooled, ground, and sieved to obtain high-temperature sintered material A, with its particle size controlled at 74μm (200 mesh sieve).

[0036] Its main components are: SiO2 content 31.3%, Al2O3 content 15.2%, CaO content 18.8%, Cl content 5.4%, BaO content 16.9%, SO3 content 8.8%, and other components 3.5%.

[0037] Example 2 Waste oil-based drilling fluid from a certain block of CNOOC in Wenchang was thermally desorbed at 400℃. After grinding and sieving, the particle size of the thermally desorbed dry residue was 150μm (100 mesh sieve) and the oil content was 0.9wt.%, thus obtaining the preliminary thermally desorbed solid phase.

[0038] The thermally desorbed solid sample was collected and heated at 1200℃. The contents of the main components were then determined. Based on the oxide content, the contents were: SiO2 29.1%, Al2O3 20.1%, CaO 14.3%, Cl 1.6%, BaO 19.9%, SO3 10.4%, and other components 4.6%.

[0039] Take 100g of the sample after heat treatment at 1200℃ and add the following admixtures: 16.6g quartz, 0g bauxite, 12.4g calcium oxide, 7.1g barite, and 5.3g calcium chloride. The particle size of the sample and each admixture is 150μm (100-mesh sieve), and the corrected mixture is obtained.

[0040] The modified mixture was calcined at 1500℃ for 1.5h, then naturally cooled, ground, and sieved to obtain high-temperature sintered material B, with its particle size controlled at 74μm (200 mesh sieve).

[0041] Its main components are: SiO2 content 32.3%, Al2O3 content 14.2%, CaO content 18.9%, Cl content 4.9%, BaO content 17.4%, SO3 content 9.1%, and other components 3.2%.

[0042] Example 3 Waste oil-based drilling fluid from a block in Huizhou, CNOOC, was thermally desorbed at 350℃. After grinding and sieving, the particle size of the thermally desorbed dry residue was 150μm (100 mesh sieve) and the oil content was 1.1wt.%, thus obtaining the preliminary thermally desorbed solid phase.

[0043] The thermally desorbed solid sample was collected and heated at 1200℃. The contents of the main components were then determined. Based on the oxide content, the contents were: SiO2 39.2%, Al2O3 14.2%, CaO 14.1%, Cl 6.9%, BaO 14.9%, SO3 7.8%, and other components 2.9%.

[0044] Take 100g of the sample after heat treatment at 1200℃ and add the following admixtures: 0g quartz, 5g bauxite, 11.3g calcium oxide, 10.2g barite, and 0g calcium chloride. The particle size of the sample and each admixture is 150μm (100 mesh sieve), and the corrected mixture is obtained.

[0045] The modified mixture was calcined at 1400℃ for 2 hours, then naturally cooled, ground, and sieved to obtain high-temperature sintered material C, with its particle size controlled at 74μm (200 mesh sieve).

[0046] Its main components are: SiO2 content 32.1%, Al2O3 content 13.2%, CaO content 20.4%, Cl content 5.6%, BaO content 17.3%, SO3 content 9.0%, and other components 2.4%.

[0047] Example 4 Waste oil-based drilling fluid from a certain block in the Bohai Sea of ​​CNOOC was thermally desorbed at 500℃. After grinding and sieving, the particle size of the thermally desorbed dry residue was 150μm (100 mesh sieve) and the oil content was 0.8wt.%, thus obtaining the preliminary thermally desorbed solid phase.

[0048] The thermally desorbed solid sample was collected and heated at 1200℃. The contents of the main components were then determined. Based on the oxide content, the contents were: SiO2 35.1%, Al2O3 18.9%, CaO 21.4%, Cl 4.8%, BaO 10.8%, SO3 5.6%, and other components 3.4%.

[0049] Take 100g of the sample after heat treatment at 1200℃ and add the following admixtures: 10.8g quartz, 0g bauxite, 6.3g calcium oxide, 23.1g barite, and 2.7g calcium chloride. The particle size of the sample and each admixture is 150μm (100-mesh sieve), and the corrected mixture is obtained.

[0050] The modified mixture was calcined at 1400℃ for 2 hours, then naturally cooled, ground, and sieved to obtain high-temperature sintered material D, with its particle size controlled at 74μm (200 mesh sieve).

[0051] Its main components are: SiO2 content 32.1%, Al2O3 content 13.2%, CaO content 19.4%, Cl content 5.2%, BaO content 18.2%, SO3 content 9.5%, and other components 2.4%.

[0052] Comparative Example 1 Waste oil-based drilling fluid from a certain block of CNOOC in Wenchang was thermally desorbed at 400℃. After grinding and sieving, the particle size of the thermally desorbed dry residue was 150μm (100 mesh sieve) and the oil content was 0.9wt.%, thus obtaining a preliminary thermally desorbed solid phase, and a comparative heat-treated sample E was obtained.

[0053] Comparative Example 2 Waste oil-based drilling fluid from a block in Huizhou, CNOOC, was thermally desorbed at 350℃. After grinding and sieving, the particle size of the thermally desorbed dry residue was 150μm (100 mesh sieve) and the oil content was 1.1wt.%, resulting in a preliminary thermally desorbed solid phase. After heating at 1200℃, a comparative heat-treated sample F was obtained.

[0054] Using high-temperature sintered materials A / B / C / D and comparative heat-treated samples E / F as raw materials, and replacing part of the cement, a cementing slurry was prepared together with other additives. The slurry, by weight, consisted of 100 parts of Grade G oil well cement, 30 parts of high-temperature sintered materials, 6 parts of fluid loss reducer, 0.2 parts of retarder, and a certain amount of fresh water. The density of the prepared cement slurry was 1.90 g / cm³. 3 .

[0055] Using high-temperature sintered materials A / B / C / D and comparative heat-treated samples E / F as raw materials, and replacing part of the cement, a cementing slurry was prepared together with other additives. The slurry, by weight, contained 100 parts of Grade G oil well cement, 30 parts of high-temperature sintered materials, 10 parts of fluid loss reducer, 0.2 parts of retarder, 3.2 parts of sodium bentonite, and a certain amount of fresh water. The density of the prepared cement slurry was 1.60 g / cm³. 3 .

[0056] The fluid loss reducing agent is an AMPS-based fluid loss reducing agent, product code C-FL80L; the retarder is an organophosphate retarder, product code C-R21L; and the cementing slurry uses sodium bentonite, product code C-P50S. All the above raw materials were purchased from Blue Ocean Boda Technology Co., Ltd.

[0057] Performance testing Table 1. Performance test results of cement slurries prepared according to the embodiments and comparative examples of this application.

[0058] In Table 1, the high-temperature sintered materials and heat-treated samples of the examples and comparative examples were added by dry mixing with cement to prepare a mixture of 1.60 g / cm³. 3 The sodium-based bentonite in the cement slurry needs to be pre-hydrated for 16 hours. The preparation and performance evaluation of the above cement slurry were carried out in accordance with the American Petroleum Institute (API) RP 10B-2 2013 standard.

[0059] As can be seen from the results in Table 1, the high-temperature sintering materials A / B / C / D prepared in Examples 1, 2, 3, and 4 have a concentration of 1.90 g / cm³. 3 The cement paste strength can reach over 14 MPa, and after treatment, the thickening time, strength, water loss, and mixing time of the four high-temperature sintering materials are basically the same, exhibiting uniformity; the heat-treated products E / F produced in Comparative Examples 1 and 2 have a strength of 1.90 g / cm³. 3 The thickening time, strength, water loss, and mixing time of cement slurry differ significantly from those of the former. This is due to the differences in the residual solid phase in the waste drilling fluid generated from drilling in different formations.

[0060] The high-temperature sintering material A / C prepared in Examples 1 and 3 has a concentration of 1.60 g / cm³. 3 The strength of low-density cement grout can reach over 3.5 MPa, which can meet the technical requirements of filling grout sections in on-site construction.

[0061] The present invention has been disclosed above with reference to preferred embodiments. However, those skilled in the art should understand that these embodiments are merely illustrative of the invention and should not be construed as limiting its scope. It should be noted that any variations and substitutions equivalent to these embodiments should be considered to be covered within the scope of the claims. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for solid-phase sintering treatment of waste oil-based drilling fluid, characterized in that, include: (1) Thermal desorption of waste oil-based drilling fluid was performed, and the resulting solid phase was obtained by grinding. (2) Collect the thermally desorbed solid sample, and determine its elemental content after heat treatment; (3) Add external admixtures to the thermally desorbed solid phase according to the element content to obtain a mixture; (4) The mixture is calcined, cooled and ground to obtain sintered material.

2. The method for solid-phase sintering treatment of waste oil-based drilling fluid according to claim 1, characterized in that, The temperature for thermal desorption is 260℃~500℃.

3. The method for solid-phase sintering treatment of waste oil-based drilling fluid according to claim 1, characterized in that, The oil content of the thermally desorbed solid phase is ≤3wt%, and the particle size is ≤150μm.

4. The method for solid-phase sintering treatment of waste oil-based drilling fluid according to claim 1, characterized in that, The admixtures include one or more of barite, calcium oxide, bauxite, quartz, and calcium chloride.

5. The method for solid-phase sintering treatment of waste oil-based drilling fluid according to claim 1, characterized in that, The admixtures comprise, by mass percentage of the thermally desorbed solid phase, 0-25.0% barite, 0-15.0% calcium oxide, 0-7.5% bauxite, 0-18.0% quartz, and 0-6.5% calcium chloride.

6. The method for solid-phase sintering treatment of waste oil-based drilling fluid according to claim 1, characterized in that, The calcination temperature is 1300~1500℃, and the duration is 0.5~2.5h.

7. A sintering material, characterized in that, It is prepared by the waste oil-based drilling fluid solid phase sintering treatment method according to any one of claims 1 to 6.

8. The sintering material according to claim 7, characterized in that, By weight percentage, it includes: SiO2 31.0%~34.5%, Al2O3 12.5%~15.5%, CaO 18.5%~22.8%, Cl 4.8%~5.6%, BaO 16.5%~18.5%, SO3 8.5%~9.5%, and other components 2%~5%.

9. A cement grout, characterized in that, Includes the sintering material as described in claim 7 or 8.

10. The application of the sintering material according to claim 7 or 8 in the preparation of cementing slurry.

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