Roadbed material prepared from waste drilling mud as well as preparation method and application of roadbed material

Abstract

The invention discloses a roadbed material prepared from waste drilling mud as well as a preparation method and application of the roadbed material, and relates to the technical field of mud resource utilization. Preparation raw materials comprise the following components in percentage by mass: 6-20% of petroleum coke residues, 1% of nano kaolin, 10-15% of ground fly ash, 0-7% of ground steel slag powder, 3-5% of silica fume, 1.5% of ferric trichloride or 2% of aluminum trichloride and the balance of waste slurry. The method has the beneficial effects that the roadbed stabilizing soil and the roadbed filling soil are mainly prepared by curing the waste mud, and roadbed curing components comprise the desulfurized petroleum coke residues, the nano kaolin, the silica fume, the ground fly ash, the ground steel slag powder and a small amount of ferric trichloride or aluminum trichloride; industrial products such as cement and lime in a conventional roadbed soil mixing ratio are replaced for preparing a roadbed soil system.

Description

Technical Field

[0001] The invention relates to the technical field of mud resource utilization, and in particular to a roadbed material prepared by utilizing waste drilling mud, and a preparation method and application thereof. Background Art

[0002] In the oil drilling process, the amount of waste drilling mud is large, the types are numerous, and the chemical composition is complex. Therefore, it is difficult to treat waste drilling mud. The current treatment methods are relatively backward. Except for a small part of recycling, most of it is simply treated by direct discharge and natural evaporation, sedimentation, drying and on-site landfill. The total amount of waste mud discharged in my country is about 2 million m3 per year. 3 Nearly half of them are directly discharged into the surrounding environment. If they are not treated safely and harmlessly, they will inevitably have a serious impact on the ecological environment and pose a major risk of environmental pollution.

[0003] With the development of economy and the increasing attention to environmental protection, the treatment of drilling waste mud has also received more and more attention. Various units have invested a lot of money to carry out research on harmless treatment of drilling mud. The most commonly used method is treatment while drilling. This method is to directly treat the drilling mud on site harmlessly, generally by adding a prepared curing agent to the mud pool for in-situ curing. The curing treatment process is a harmless treatment process that is widely used at home and abroad. However, due to the different requirements of local environmental protection departments and the differences in the composition of mud in different oil fields, the curing process and curing agent are also different, making the curing treatment effect uneven. The direction of development of treatment technology is to keep drilling mud away from the ground and to make comprehensive use of it. However, the technology in the domestic oil production industry is not mature enough, and the engineering cases are relatively insufficient. Therefore, in order to promote energy conservation and emission reduction in oil fields and achieve the purpose of comprehensive utilization of drilling waste mud, it is very necessary to carry out research on the recovery and reuse of drilling waste mud.

[0004] In the exploitation of oil fields, it is often necessary to build some infrastructure, especially in some remote areas. Good transportation is a necessary condition for the smooth production of oil and gas. In view of the physical, chemical and mechanical properties of the drilling waste mud after solidification, it is very feasible to carry out resource recycling of the drilling waste mud after solidification. At present, there are relatively mature drilling mud solidification technologies at home and abroad, and there are also relatively rich research and practical experience, but there are few studies on the use of solidified improved soil as roadbed fill, and there are few related applications of solidified mud as roadbed fill / improved soil / stabilized soil and other soil cushion layers, and some indicators of solidified soil generally cannot meet the standard requirements of roadbed fill.

[0005] Petroleum coke is a by-product produced during the refining process of oil refining enterprises. In the process of oil refining, more petroleum coke by-products are produced, which are high in sulfur content, heavy metals, poor in appearance and difficult to use. This part of petroleum coke has the characteristics of high carbon content, high calorific value and certain volatility. It can become a good high calorific value solid fuel and has high utilization value. However, petroleum coke will produce a large amount of corrosive gas during the combustion process, which will cause great damage to the boiler. In order to solve this problem, circulating fluidized bed combustion technology is selected. After the petroleum coke and limestone are ground into fine powder and fully mixed, they are sprayed into the high-temperature gas in the furnace at 1600℃. The limestone decomposes into calcium oxide and carbon dioxide. The sulfur dioxide produced when the petroleum coke is burned reacts with calcium oxide to form calcium sulfate. After passing through the cyclone separation equipment, the mixture of calcium sulfate and unreacted calcium oxide is called petroleum coke slag. Affected by various factors such as combustion temperature, feeding speed, and type of petroleum coke, the content of each component in the petroleum coke slag is unstable, but the main chemical components are CaO and CaSO4.

[0006] Since the content of each component of petroleum coke slag is not fixed, the treatment of petroleum coke slag has always been a problem that troubles power generation companies. Petroleum coke slag is different from domestic waste and construction waste. Domestic waste can be burned, composted, buried in pits, etc., while construction waste can be used for land reclamation, as roadbed materials, and to prepare recycled aggregates. Petroleum coke slag has its own difficulties. Petroleum coke slag itself is difficult to degrade and the calcium oxide in petroleum coke slag will pollute water sources. Petroleum coke slag is unstable as a roadbed filling material, and the quality of the project is difficult to guarantee. At present, petroleum coke slag can only be piled up in the open air. With the in-depth research on geopolymers, the utilization value of industrial waste containing high active ingredients such as slag, fly ash, and kaolin has become more prominent, and the preparation of green cementitious materials from alkali-activated slag is a gradually mature theory. Slag is an industrial by-product of the smelting process of steel enterprises. It once troubled many steel enterprises as industrial waste. Studies have found that slag has certain activity in an alkaline environment and can replace cement as a building material. The activators that have a greater impact on the activity of slag include calcium oxide, hemihydrate gypsum, dihydrate gypsum, sodium sulfate, etc. The composite excitation intensity theory has proved that the combined effect of multiple activators on slag has higher strength and better durability than that of slag excited by a single activator. Simple sulfate has little effect on the strength of slag and requires an alkaline environment. This provides a theoretical basis for the utilization of petroleum coke slag.

[0007] Adopting more environmentally friendly measures to deal with drilling waste mud, treat it harmlessly, reduce pollution to the environment, and conduct regional governance will not only not affect economic benefits, but also clear obstacles for the development of the oil and gas industry, further promote the vigorous development of the oil and gas industry, and achieve sustainable development advocated in the 21st century. We will unswervingly protect the environment, advocate a green economy, build a green home, and create a harmonious blueprint.

[0008] In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a roadbed material prepared by utilizing drilling waste mud, which can avoid secondary pollution and “treat waste with waste”, and a preparation method and application thereof. Summary of the invention

[0009] In order to achieve the above-mentioned purpose of the invention and to address the above-mentioned technical problems, the present invention provides a roadbed material prepared by using waste drilling mud, and a preparation method and application thereof.

[0010] The technical solution is that the raw materials for preparation include the following components according to the percentage by mass:

[0011] 6-20% petroleum coke residue, 1% nano kaolin, 10-15% ground fly ash, 0-7% ground steel slag powder, 3-5% silica fume, 1.5% ferric chloride or 2% aluminum chloride and the rest waste mud;

[0012] The pH value of the waste mud is 8.5-10, the water content is 48.4%, and the physical indicators of the waste mud are shown in Table 1.

[0013] Table 1 Basic physical indicators of the original drilling waste mud in the test

[0014]

[0015] The raw materials for preparation include the following components according to mass percentage:

[0016] Petroleum coke residue 20%, nano kaolin 1%, ground fly ash 10%, silica fume 4%, aluminum chloride 2% and the rest waste mud.

[0017] The petroleum coke residue, nano-kaolin and silica fume are stimulating components, the ground fly ash and ground steel slag powder are active components, and the ferric chloride or aluminum chloride is a pH lowering component, which replaces industrial products such as cement and lime in conventional roadbed soil mixes to prepare a roadbed soil system.

[0018] The specific surface area of ​​the ground steel slag powder is 430-450m 2 / kg, the ground fly ash is Class II ash.

[0019] The specific surface area of ​​the silica fume is 1750m 2 / kg.

[0020] The mineral components of the petroleum coke slag are: 60-70% CaO, 20-30% SO3, 0-6% SiO2, 0-2% MgO, 0-2% Fe2O3, and its main chemical components are CaO and CaSO4.

[0021] The chemical composition of the ground fly ash is: 65-75% SiO2, 20-25% Al2O3, 0-0.5% CaO, 0-0.5% MgO, 2-3% Fe2O3, 0-0.5% Na2O, 0-1% TiO2, 0-3% SO3, 0-0.5% P2O5, and 0-2% LOI.

[0022] The chemical composition of the ground steel slag powder is: 30-40% CaO, 20-30% SiO2, 10-15% Al2O3, 10-20% Fe2O3, 8-15% MgO, 0-3% MnO, 0-3% SO3, and 0-0.5% Na2O.

[0023] The method for preparing roadbed material using waste drilling mud comprises the following steps:

[0024] (1) In addition to routine preparations, prepare cement, desulfurized petroleum coke slag, fly ash and other curing agents; according to the actual project conditions, set up access roads for mixing machinery, provide a bearing area for the initial mixing of the machinery in advance, and prepare curing agent storage tanks near the machinery in advance;

[0025] Equipment preparation includes preparing the machines and tools required for filling and mixing, calibrating and debugging the mixer according to the mixing ratio required by the design; it is also necessary to prepare construction machinery such as loaders, bulldozers, graders, rollers, and transport vehicles;

[0026] (2) On-site mixing

[0027] Due to the high water content of the mud, it is not easy to transport it. Therefore, the mud is treated by mixing and solidifying it in the mud pool. According to the effective treatment range of the equipment, a 1m×1m grid is roughly drawn with a hanging line to calculate the dosage of the curing agent for each grid. There should be an overlap width of not less than 10cm between each grid to avoid missing mixing. After each grid is mixed, the whole grid is mixed.

[0028] First, the ground with bearing capacity on the bank of the mud pool is used as the laying platform, and the laying is carried out along the outer circle of the mud pool; after the mud in the above-treated sub-block is stirred, it is leveled, and after the improved mud strength reaches the bearing capacity requirement, the steel plate is laid on it, and the mixing equipment is placed on the solidified sub-block. This block of solidified soil is used as a solidification platform, and the next untreated area is solidified in a push-up manner;

[0029] Place the evenly mixed soil sample in a mixing tank for curing, and take samples to measure the moisture content and CBR;

[0030] (3) Site cleaning and construction layout

[0031] Clean up the debris on the road surface and sprinkle water to moisten it; re-lay out the center line on the road subbase; set up stakes every 15 to 20 meters in straight sections, every 10 to 15 meters in flat curve sections, and every 0.3 to 0.5 meters outside the edge of the shoulder on both sides; set up marks on the stakes on both sides, and conduct elevation measurements to mark the design height of the edge;

[0032] (4) Paving

[0033] After mixing, according to the moisture content of the improved mud in the mud pool, when it is about to reach the optimal moisture content, the mud-improved soil is dug out from the mud pool by an excavator and transported to the roadbed to be filled. The loose laying thickness is 22cm-25cm.

[0034] The roadbed material prepared by the preparation method is applied to the soil cushion layer of roadbed filling, improved soil or stabilized soil.

[0035] Drilling waste mud is mainly composed of clay, water, chemical additives and some inert substances. The physical properties of drilling waste mud measured by water content test, compaction test, liquid limit and plastic limit combined determination test are shown in Table 1:

[0036] Table 1 Basic physical indicators of the original drilling waste mud in the test

[0037]

[0038] The main phases in the original drilling waste mud are: diopside (CaMg(Si2O6)), orthorhombic calcite (Ca4(Si3O9)(OH)2), quartz (SiO2), sanidine (KAlSi3O8), mica (KAl2(Al3O 10 )(OH)2), and may also contain small amounts of chlorite, carbonate minerals, tremolite, actinolite, serpentine, pyrophyllite, rutile, apatite, etc.

[0039] Since oilfield drilling requires the injection of certain drugs, the pH value of the waste mud is relatively high, generally between 8.5 and 10, so it cannot be directly recycled and utilized.

[0040] This application mainly uses waste mud solidification to prepare roadbed stabilized soil / roadbed fill. Petroleum coke residue, nano-kaolin, silica fume, etc. are used as stimulating components, ground fly ash and ground steel slag powder are used as active components, and ferric chloride or aluminum chloride is used as pH-lowering components to replace industrial products such as cement and lime in conventional roadbed soil mix ratios to prepare a roadbed soil system.

[0041] In order to achieve the reduction and disposal of construction waste, this project attempts to use waste mud to solidify and prepare roadbed stabilized soil. The waste mud has a complex composition, such as the presence of minerals such as montmorillonite, potassium feldspar and sodium feldspar, with a Cl content as high as 3.415%. It also contains some organic matter and other volatile substances or substances that are easily decomposed at high temperatures, making it impossible to use it directly as roadbed soil. Certain improvement measures must be taken to ensure the normal use requirements of the roadbed.

[0042] At present, there are many external components commonly used to improve soil, such as lime, cement, lime and fly ash composite, cement and lime composite, etc. However, lime and cement are expensive and have poor economic efficiency, and there is an urgent need to find new improved components. In addition, for mud and sand slag, it is often necessary to pre-screen the aggregate and soil to facilitate the preparation of roadbed stabilized soil. Therefore, based on the action mechanism of lime and cement improved soil, this application proposes to use petroleum coke slag, nano-kaolin, and silica fume as excitation components, ground fly ash and ground steel slag powder as active components, and ferric chloride or aluminum chloride as pH-lowering components as auxiliary materials to prepare roadbed stabilized soil.

[0043] Preliminary optimization of experimental scheme

[0044] According to the "Testing Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" (JTG / E51-2009), 100mm×100mm cylindrical specimens were prepared, maintained and tested at 20℃±2℃ and above 95% relative humidity. The effects of cementitious materials, petroleum coke residue, fly ash and curing agent on the performance of stabilized soil on the roadbed were analyzed. The specific test material dosage is shown in Table 2, where the water consumption is controlled based on the agglomeration effect of the stabilized soil on the roadbed during mixing. The unconfined compressive strength test results of stabilized soil on the roadbed are shown in Table 3.

[0045] Table 2

[0046]

[0047] Table 3 Unconfined compressive strength test results of roadbed stabilized soil

[0048]

[0049] Since silica fume reacts with nano-kaolin and steel slag powder, some products such as calcium aluminate, calcium silicate hydrate gel (CSH) and Ca(OH)2 are obtained, which cause linkage and compaction, thus providing strength. Therefore, a higher strength solidified soil sample can be obtained.

[0050] The CBR value of the solidified soil part measured in the experiment is shown in Table 4, which meets the requirements of Class III and Class IV highways. Therefore, subsequent environmental impact experiments and field tests are carried out according to the adjusted experimental mix ratio.

[0051] Table 4 CBR values ​​of experimental roadbed stabilized soil

[0052]

[0053] The heavy compaction test showed that the optimal moisture content of the solidified soil was 25%, the maximum dry density was 1.51 g / cm3, the compaction degree was ≥94%, the plastic limit was 24.4%, the liquid limit was 46.1%, and the plasticity index was 21.763.

[0054] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention are as follows: the present invention mainly utilizes waste mud solidification to prepare roadbed stabilized soil and roadbed fill, and the roadbed solidification components include desulfurized petroleum coke slag, nano-kaolin, silica ash, ground fly ash, ground steel slag powder and a small amount of ferric chloride or aluminum chloride. Oil refining industrial waste slag, nano-kaolin, silica ash, etc. are used as excitation components, ground fly ash and ground steel slag powder are used as active components, and ferric chloride or aluminum chloride is used as pH lowering components to replace industrial products such as cement and lime in conventional roadbed soil mix ratios to prepare a roadbed soil system.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] (1) “Use waste to treat waste”, using the synergistic effect of petroleum coke residue, drilling waste mud, slag, etc. to achieve resource utilization of solid waste to make roadbed soil;

[0057] (2) obtaining the composition ratio of desulfurized petroleum coke residue, nano-kaolin, ground fly ash, ground steel slag, waste mud, silica fume, ferric chloride, aluminum chloride, etc.;

[0058] (3) Compared with CN202111288972.1, the present invention replaces the use of cement products in the conventional roadbed soil mix ratio, thereby reducing the cost of roadbed soil preparation; the prepared roadbed soil meets the third and fourth level highway standards in the Highway Geotechnical Test Code (JTG3430-2020);

[0059] (4) Other indicators of roadbed soil: The optimal moisture content of the solidified soil measured by heavy compaction test is 25%, the maximum dry density is 1.51 g / cm3, the compaction degree is ≥ 94%, the plastic limit is 24.4%, the liquid limit is 46.1%, and the plasticity index is 21.763.

[0060] (5) The present invention does not require the waste sludge to be incinerated, thus reducing process steps and costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 It is a diagrammatic representation of the desulfurized petroleum coke slag of the present invention.

[0062] Figure 2This is the diffraction pattern of petroleum coke residue.

[0063] Figure 3 This is a diagram of the finished roadbed pattern. DETAILED DESCRIPTION

[0064] The chemical composition of the waste oilfield mud used in the following examples is shown in Table 1, with a water content of 48.4% and a pH value of 9.5. The desulfurized petroleum coke residue includes 40.5% CaSO4, 41.6% CaO and the remainder of impurities.

[0065] The raw materials for the preparation of the examples and comparative examples are shown in Table 5.

[0066] Table 5 Preparation materials of examples and comparative examples (wt.%)

[0067]

[0068]

[0069] Example 1

[0070] Calculated by mass percentage, the roadbed material prepared by 6% petroleum coke residue, 1% nano kaolin, 15% ground fly ash, 7% ground steel slag powder, 5% silica fume, 2% aluminum chloride and the remainder of waste mud is mixed evenly and filled into the site for rolling to obtain roadbed fill.

[0071] Example 2

[0072] Calculated by mass percentage, the roadbed material prepared by 10% petroleum coke residue, 1% nano kaolin, 10% ground fly ash, 5% ground steel slag powder, 3% silica fume, 1.5% ferric chloride and the remainder of waste mud is mixed evenly and filled into the site for rolling to obtain roadbed fill.

[0073] Example 3

[0074] Calculated by mass percentage, the roadbed material prepared by 20% petroleum coke residue, 1% nano kaolin, 10% ground fly ash, 4% silica fume, 2% aluminum chloride and the remainder of waste mud is mixed evenly and filled into the site for rolling to obtain roadbed fill.

[0075] The performance tests were performed on the roadbed materials prepared in the above examples and comparative examples:

[0076] The unconfined compressive strength test of the materials of the examples and comparative examples was carried out with reference to the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" (JTG / E51). The results showed that the unconfined compressive strength of the roadbed soil prepared in Example 1 was 2.10 MPa, that of Example 2 was 2.19 MPa, and that of Example 3 was 3.40 MPa.

[0077] The bearing ratio (CBR) performance test of the obtained roadbed was carried out with reference to the "Highway Geotechnical Test Code" (JTG3430-2020). The results showed that the CBR values ​​of the roadbeds obtained in Example 1, Example 2, and Example 3 after 7d maintenance were 14%, 17%, and 25%, respectively, which all met the requirements of the "Technical Specifications for Highway Roadbed Construction" (JTG3610-2019) for third and fourth grade highways, and the pH values ​​of Examples 1, 2, and 3 can be reduced to 7.7, 7.4, and 8.

[0078] Nano kaolin refers to kaolin powder that is made by crushing the kaolin ore coarsely and medium with a crusher, then ultra-finely pulverizing it with an impact mill, and then calcining and airflow ultra-fine pulverizing it.

[0079] Desulfurized petroleum coke slag is a combustion product of CFB boiler of Sinopec Qingdao Refining and Chemical Co., Ltd. Petroleum coke is a common byproduct of petrochemical refineries and has good industrial application performance. Lime powder is mixed with petroleum coke and then sprayed into the fluidized bed boiler. After full combustion, the waste residue obtained is desulfurized petroleum coke slag. It is light yellow and has a fineness similar to fine sand. Figure 1 shown.

[0080] The XRF analysis results of the experimental petroleum coke slag are shown in Table 6 below.

[0081] Table 6 XRF analysis results of petroleum coke slag / %

[0082]

[0083] Figure 2 The diffraction pattern of petroleum coke slag shows that the main components of desulfurized petroleum coke slag are lime and anhydrite, both of which are traditional hardening activator materials for roadbed soil.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A roadbed material prepared using waste drilling mud, characterized in that: The raw materials for preparation include the following components according to mass percentage: 6-20% petroleum coke residue, 1% nano kaolin, 10-15% ground fly ash, 0-7% ground steel slag powder, 3-5% silica fume, 1.5% ferric chloride or 2% aluminum chloride and the rest waste mud; The pH value of the waste mud is 8.5-10, the water content is 48.4%, and the physical indicators of the waste mud are shown in Table 1. Table 1 Basic physical indicators of the original drilling waste mud in the test 2. The roadbed material prepared by using waste drilling mud according to claim 1, characterized in that: The raw materials for preparation include the following components according to mass percentage: Petroleum coke residue 20%, nano kaolin 1%, ground fly ash 10%, silica fume 4%, aluminum chloride 2% and the rest waste mud.

3. The roadbed material prepared by using waste drilling mud according to claim 1, characterized in that: The petroleum coke residue, nano-kaolin and silica fume are excitation components, the ground fly ash and ground steel slag powder are active components, and the ferric chloride or aluminum chloride is a pH lowering component.

4. The roadbed material prepared by using waste drilling mud according to claim 1, characterized in that: The specific surface area of ​​the ground steel slag powder is 430-450m 2 / kg, the ground fly ash is Class II ash.

5. The roadbed material prepared by using waste drilling mud according to claim 1, characterized in that: The specific surface area of ​​the silica fume is 1750m 2 / kg.

6. The roadbed material prepared by using waste drilling mud according to claim 1, characterized in that: The mineral components of the petroleum coke slag are: 60-70% CaO, 20-30% SO3, 0-6% SiO2, 0-2% MgO, 0-2% Fe2O3, and its main chemical components are CaO and CaSO4.

7. The roadbed material prepared by using waste drilling mud according to claim 1, characterized in that: The chemical composition of the ground fly ash is: 65-75% SiO2, 20-25% Al2O3, 0-0.5% CaO, 0-0.5% MgO, 2-3% Fe2O3, 0-0.5% Na2O, 0-1% TiO2, 0-3% SO3, 0-0.5% P2O5, and 0-2% LOI.

8. The roadbed material prepared by using waste drilling mud according to claim 1, characterized in that: The chemical composition of the ground steel slag powder is: 30-40% CaO, 20-30% SiO2, 10-15% Al2O3, 10-20% Fe2O3, 8-15% MgO, 0-3% MnO, 0-3% SO3, and 0-0.5% Na2O.

9. The roadbed material prepared by using waste drilling mud according to claim 1, characterized in that: The preparation method of the roadbed material comprises the following steps: (1) Mixing on site According to the blending ratio required by the design, petroleum coke residue, nano-kaolin, ground fly ash, ground steel slag powder, silica fume, ferric chloride or aluminum chloride and the remaining waste mud are mixed and stirred at room temperature until uniform; (2) Curing treatment Add the curing agent to the mud and stir until smooth.

10. A roadbed material prepared by the preparation method according to any one of claims 1 to 9, wherein the roadbed material is used for a soil cushion layer of roadbed fill, improved soil or stabilized soil.

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