Drilling fluid based on alkane derivative oil-based base fluid and preparation method thereof

Abstract

The invention discloses drilling fluid based on alkane derivative oil-based base fluid and a preparation method of the drilling fluid, and relates to the field of petrochemical engineering refining. The drilling fluid based on the alkane derivative oil-based basic liquid comprises the following components in parts by weight: 0.1-100 parts of the alkane derivative oil-based basic liquid, 0.1-100 parts of a lubricant, 0.1-5 parts of a main emulsifier, 0.1-5 parts of an auxiliary emulsifier, 0.1-5 parts of organic soil, 0.1-20 parts of a calcium chloride solution, 0.1-5 parts of a filtrate reducer, 0.1-5 parts of calcium oxide, 0.1-5 parts of calcium carbonate and 0.1-5 parts of a nano plugging agent. 0.1-5 parts of a film-forming blocking agent and 30-80 parts of barite. The low-temperature rubber material meets the low-temperature operation requirement, can improve the operation environment, is excellent in performance, stable in performance after high-temperature aging and good in compatibility with drilling equipment rubber parts, and effectively solves the problems of high cost, poor flowability, existence of pollution and pungent smell and unstable performance in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of petrochemical refining, and in particular to a drilling fluid based on an alkane derivative oil base fluid and a preparation method thereof. BACKGROUND

[0002] In recent years, with the deepening of oil and gas resource development, complex wells and complex oil and gas resources continue to advance. Drilling technology, as a core link of oil and gas exploration and development, directly determines the efficiency, cost and environmental protection level of resource exploitation. Advanced drilling technology has become the key guarantee for breaking through the development bottleneck, realizing cost reduction and efficiency increase, and green environmental protection. Drilling fluid has many important functions in the drilling process, such as cleaning the bottom of the well, cooling and lubricating the drill bit and drill string, balancing the formation pressure, suspending the cuttings, transmitting hydraulic power, bearing the weight of the drilling tool, and providing information of the drilled formation. Its performance directly determines the drilling efficiency and plays a crucial role in the process of petrochemical drilling. As an important component of oil-based drilling fluid, oil-based base fluid has attracted great attention from researchers.

[0003] Traditional oil-based drilling fluid base oil is mostly diesel oil, white oil, etc. However, diesel oil has poor low-temperature fluidity (especially in cold regions), high cost, poor low-temperature fluidity, and certain pollution, which affects the overall performance and use effect of the drilling fluid. Unconventional crude oil, as a kind of unconventional alkane derivative resource, has light distillate oil with similar alkane structure as diesel oil, and is rich in source and low in cost, which is expected to replace part of diesel oil as base oil. In the prior art, there are methods for preparing oil-based base fluid by mixing various crude oil fractions, but there are often problems such as unreasonable raw material ratio and improper selection of additives, which lead to unstable product performance and cannot meet the actual use requirements. Therefore, it is of great practical value to develop an oil-based base fluid with optimized performance based on unconventional oil light distillate oil and to prepare a high-performance drilling fluid based thereon. In order to solve the above problems, researchers have done a lot of research work on base oil and drilling fluid configuration.

[0004] In the prior art, a preparation method of drilling fluid base oil includes the following steps: (1) separating Fischer-Tropsch synthesis products into a middle fraction and lower fraction and heavy tail fraction with boiling points, and the middle fraction has a boiling point between the lower fraction and the heavy tail fraction; (2) distilling and cutting the obtained middle fraction into several fractions; (3) isomerizing at least one of the cut fractions, and controlling the isomerization degree at 50-100%; (4) according to the application requirements of the drilling fluid, blending the obtained isomerized and non-isomerized middle fractions in proportion; and (5) distilling the blended product to remove hydrogenated isomerization by-products low-carbon hydrocarbons to obtain the product. Some disclose a drilling fluid base oil with high paraffin and low aromatic produced by using mineral oil as raw material and a process thereof, and the preparation method includes the following steps: (1) mixing the mineral base fraction oil and hydrogen gas, and then entering a first reaction zone provided with a catalyst to react; (2) the reaction product flowing out of the first reaction zone continues to enter a second reaction zone provided with a catalyst to react; and (3) the reaction product flowing out of the second reaction zone is subjected to high-pressure separation, stripping and fractionation to obtain unconverted bottom oil, which is high paraffin oil base drilling fluid base oil. Some disclose a preparation method of super-high-temperature-resistant oil-based drilling fluid, and the specific configuration method is as follows: (1) under the condition of sufficient stirring, the emulsifier, wetting agent, cutting agent, tackifier, alkalinity regulator are sequentially added into the mixing funnel, and the tackifier is fully dispersed and the emulsifier is uniformly dissolved; (2) the prepared calcium chloride brine is pumped into the mixing funnel by an air diaphragm pump, and is slowly added and fully emulsified; no free water droplets can be seen, that is, no obvious water beads, otherwise the stirring and shearing need to be continued until the "water droplet" phenomenon disappears; (3) the fluid loss additive is added under stirring condition and fully stirred uniformly; and (4) the plugging agent and weighting agent are slowly added into the mixing funnel under stirring condition, and fully stirred uniformly. Among them, the content of the base oil is 42.00%-95.00%, the content of the emulsifier is 0.90%-2.60%, the content of the wetting agent is 0.50%-2.50%, the content of the tackifier is 0.20%-3.50%, the content of the cutting agent is 0.00%-0.30%, the content of the fluid loss additive is 1.00%-3.00%, the content of the alkalinity regulator is 0.90%-3.00, the content of the calcium chloride brine is 5.00%-2.00%, the content of the plugging agent is 0.00%-2.00%, and the content of the weighting agent reaching the specified density.Also disclosed is a method of making base oil from a Fischer-Tropsch synthesis product, comprising: (1) separating the Fischer-Tropsch synthesis product into a fraction (i) having a boiling point in the middle distillate range and lower, a heavy ends fraction (iii), and an intermediate base oil precursor fraction (ii) having a boiling point between the fraction (i) and the fraction (iii); (2) subjecting the base oil precursor fraction (ii) to catalytic hydroisomerization and catalytic dewaxing processes to produce one or more base oil grades; (3) subjecting the heavy ends fraction (iii) to a conversion step to produce a fraction (iv) having a boiling point lower than the heavy ends fraction (iii); (4) subjecting a high boiling fraction (v) of the fraction (iv) to catalytic hydroisomerization and catalytic dewaxing processes to produce one or more base oil grades.

[0005] The present application is combined with the simple operability of the existing cutting fractionation technology, and is further expanded to a more extensive unconventional oil base oil preparation. Since the oil base oil directly fractionated may have differences in parameters such as rheological property, demulsification voltage, and high temperature and high pressure filtration loss, it needs to be further blended and configured to meet the application requirements in different occasions. SUMMARY

[0006] In view of the above problems in the prior art, the present application provides a drilling fluid based on an alkane derivative oil base and a preparation method thereof, which effectively solves the problems of high cost, poor flowability, existence of polluting and irritating odor, and unstable performance in the prior art.

[0007] To achieve the above object, the technical scheme adopted by the present application to solve its technical problem is to provide a preparation method of a drilling fluid based on an alkane derivative oil base, comprising the following steps: adding a main emulsifier and an auxiliary emulsifier to the alkane derivative oil base, stirring uniformly, then adding organic clay, stirring uniformly, then adding calcium chloride solution, stirring uniformly, then adding filtration loss reducing agent, stirring uniformly, then adding calcium oxide, stirring uniformly, then adding film-forming plugging agent, stirring uniformly, then adding calcium carbonate, stirring uniformly, then adding nano plugging agent, stirring uniformly, and then adding barite to obtain the drilling fluid based on the alkane derivative oil base.

[0008] Further, the above drilling fluid based on the alkane derivative oil base comprises the following components by weight: 0.1-100 parts of alkane derivative oil base, 0-100 parts of lubricant, 0.1-5 parts of main emulsifier, 0.1-5 parts of auxiliary emulsifier, 0.1-5 parts of organic clay, 0.1-20 parts of calcium chloride solution, 0.1-5 parts of filtration loss reducing agent, 0.1-5 parts of calcium oxide, 0.1-5 parts of calcium carbonate, 0.1-5 parts of nano plugging agent, 0.1-5 parts of film-forming plugging agent, and 30-80 parts of barite.

[0009] Further, the drilling fluid based on the alkane derivative oil-based base fluid comprises the following components by weight: 50 parts of the alkane derivative oil-based base fluid, 50 parts of a lubricant, 2 parts of a main emulsifier, 1 part of an auxiliary emulsifier, 2 parts of an organic clay, 6 parts of a calcium chloride solution, 3 parts of a pour point depressant, 1 part of calcium oxide, 3 parts of calcium carbonate, 1 part of a nano plugging agent, 1 part of a film-forming plugging agent, and 30 parts of barite.

[0010] Further, the alkane derivative oil-based base fluid is prepared by the following method: the raw oil is pretreated, heated, and then divided into different fractions to obtain an alkane derivative fraction oil, and then a pour point depressant and a plant odor remover are added in sequence, and stirred uniformly to obtain the alkane derivative oil-based base fluid.

[0011] Further, the raw oil is at least one of shale oil, oil sand, super heavy oil, and asphalt.

[0012] Further, the heating is performed in a heating furnace at room temperature to 750°C.

[0013] Further, the different fractions are divided by atmospheric distillation and vacuum distillation.

[0014] Further, the alkane derivative oil-based base fluid comprises the following components by weight: 0.1-100 parts of the alkane derivative fraction oil, 0.1-1 part of the pour point depressant, and 0.1-1 part of the plant odor remover.

[0015] Further, the alkane derivative oil-based base fluid comprises the following components by weight: 80 parts of the alkane derivative fraction oil, 1 part of the pour point depressant, and 1 part of the plant odor remover.

[0016] Further, the distillation range of the alkane derivative fraction oil is 30-80%.

[0017] Further, the distillation range of the alkane derivative fraction oil is 50%.

[0018] Further, the pour point depressant is a poly-alpha-olefin pour point depressant or / and a maleic anhydride copolymer pour point depressant.

[0019] Further, the plant odor remover is one of D-limonene, citric acid, and malic acid.

[0020] Further, the pour point depressant and the plant odor remover are added at 50-60°C, and stirred at 1000-1200 r / min for 30-40 min.

[0021] Further, the lubricant is diesel oil.

[0022] Further, the main emulsifier is at least one of a soapy fatty acid, an alkylphenol polyoxyethylene ether, a quaternary ammonium salt, and a betaine.

[0023] Further, the auxiliary emulsifier is stearic acid or / and octadecanol.

[0024] Furthermore, the organic soil is bentonite.

[0025] Furthermore, the concentration of the calcium chloride solution is 15-25 wt%.

[0026] Furthermore, the concentration of the calcium chloride solution is 20 wt%.

[0027] Furthermore, the filtration agent is an oil-soluble phenolic resin.

[0028] Furthermore, the nano-blocking agent is one of nano-silica, nano-calcium carbonate, and nano-clay.

[0029] Furthermore, the film-forming sealing agent is one of asphalt, phenolic resin, epoxy resin, and urea-formaldehyde resin.

[0030] Further, after adding the primary emulsifier and secondary emulsifier to the alkane derivative oil-based base liquid, stir at 10000-12000 r / min for 10-15 min.

[0031] Further, after adding organic soil, stir at 10000-12000 r / min for 10-15 min.

[0032] The beneficial effect of taking the above-mentioned further measures is that it enables the organic soil to be fully dispersed.

[0033] Further, after adding calcium chloride solution, stir at 10000-12000 r / min for 20-25 min.

[0034] The beneficial effect of adopting the above-mentioned further measures is to form a water-in-oil emulsion system.

[0035] Further, after adding the filtration reducer, stir at 10000-12000 r / min for 10-20 min.

[0036] Further, after adding calcium oxide, stir at 10000-12000 r / min for 10-20 min.

[0037] Further, after adding calcium carbonate, stir at 10000-12000 r / min for 10-20 min.

[0038] Furthermore, after adding the nano-blocking agent, stir at 10000-12000 r / min for 10-20 min.

[0039] Further, after adding the film-forming blocking agent, stir at 10000-12000 r / min for 10-20 min.

[0040] Further, after adding barite, stir at 8000-10000 r / min for 30-40 min.

[0041] Furthermore, barite was added to adjust the density of the alkane derivative oil-based drilling fluid to 1.6-1.8 g / cm³. 3 .

[0042] Furthermore, barite was added to adjust the density of the alkane derivative oil-based drilling fluid to 1.7 g / cm³. 3 .

[0043] The drilling fluid based on alkane derivative oil-based base fluid is prepared by the above-mentioned method for preparing drilling fluid based on alkane derivative oil-based base fluid.

[0044] In summary, the present invention has the following beneficial effects: 1. Advantages of oil-based base fluid: It is mainly composed of light distillate oil of alkane derivatives-based base fluid, which reduces the raw material cost by 15-20% compared with pure diesel oil; the pour point depressant can reduce the pour point of the base fluid to below -40℃, which meets the requirements of low temperature operation; the plant deodorizer effectively reduces the irritating odor and improves the working environment.

[0045] 2. Advantages of drilling fluid: The synergistic effect of each substance makes the drilling fluid prepared based on the base fluid have a plastic viscosity of 25-70 mPa·s at 65℃, dynamic shear force of 8-30 Pa, demulsification voltage of >500V, stable performance after high temperature (120℃) aging, filtration loss of <5mL, and good compatibility with rubber parts of drilling equipment. Detailed Implementation

[0046] The principles and features of this invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0047] Example 1 A drilling fluid based on an alkane derivative oil-based base fluid, the preparation method of which includes the following steps: The oil sands were pretreated by desalting and dehydrating to remove impurities. The oil was then heated in a furnace at 750°C. Different fractions were obtained through atmospheric and vacuum distillation to yield alkane derivative oils. The first 50% of the oil was lightly processed. Poly(α-olefin) pour point depressant and D-limonene were then added sequentially, and the mixture was stirred at 1000 rpm for 30 min at 50°C to obtain an alkane derivative oil-based base liquid. Diesel fuel, anionic fatty acid soap, and stearic acid were added to the base liquid, and the mixture was stirred at 10000 rpm for 10 min. Bentonite was then added and stirred at 10000 rpm for 15 min to ensure thorough dispersion. A calcium chloride solution (20 wt%) was added and stirred at 12000 rpm for 20 min to form a water-in-oil emulsion system. Oil-soluble phenolic resin was then added. After adding resin, stir at 12000 rpm for 20 min. Then add calcium oxide and stir at 12000 rpm for 20 min. Next, add phenolic resin and stir at 12000 rpm for 20 min. Then add calcium carbonate and stir at 12000 rpm for 20 min. Finally, add nano-silica and stir at 12000 rpm for 20 min. Add barite and stir at 10000 rpm for 30 min. Adjust the density of the alkane derivative oil-based drilling fluid to 1.7 g / cm³. 3 Drilling fluids based on alkane derivative oil-based base fluids are obtained.

[0048] The drilling fluid based on alkane derivative oil-based base fluid mentioned above comprises the following components by weight: 80 parts alkane derivative oil-based base fluid, 2 parts anionic fatty acid soap, 1 part stearic acid, 2 parts bentonite, 6 parts calcium chloride solution, 3 parts oil-soluble phenolic resin, 1 part calcium oxide, 3 parts calcium carbonate, 1 part nano silica, 1 part phenolic resin, and 30 parts barite.

[0049] The above-mentioned alkane derivative oil-based base fluid includes the following components by weight: 98 parts alkane derivative distillate oil, 1 part polyα-olefin pour point depressant, and 1 part D-limonene.

[0050] Example 2 A drilling fluid based on an alkane derivative oil-based base fluid, the preparation method of which includes the following steps: Shale oil is pretreated by desalting and dehydrating to remove impurities. It is then heated in a furnace at 750°C. Different fractions are obtained through atmospheric and vacuum distillation to yield alkane derivative oils. The first 60% of the distillate is the lightest fraction. Poly(α-olefin) pour point depressant and D-limonene are then added sequentially, and the mixture is stirred at 1000 rpm for 30 min at 50°C to obtain an alkane derivative oil-based base liquid. Diesel fuel, anionic fatty acid soap, and stearic acid are added to the base liquid, and the mixture is stirred at 10000 rpm for 10 min. Bentonite is then added and stirred at 10000 rpm for 15 min to ensure thorough dispersion. A calcium chloride solution (20 wt%) is added and stirred at 12000 rpm for 20 min to form a water-in-oil emulsion system. Oil-soluble phenolic resin is then added. After adding resin, stir at 12000 rpm for 20 min. Then add calcium oxide and stir at 12000 rpm for 20 min. Next, add phenolic resin and stir at 12000 rpm for 20 min. Then add calcium carbonate and stir at 12000 rpm for 20 min. Finally, add nano-silica and stir at 12000 rpm for 20 min. Add barite and stir at 10000 rpm for 30 min. Adjust the density of the alkane derivative oil-based drilling fluid to 1.7 g / cm³. 3 Drilling fluids based on alkane derivative oil-based base fluids are obtained.

[0051] The drilling fluid based on alkane derivative oil-based base fluid mentioned above comprises the following components by weight: 60 parts alkane derivative oil-based base fluid, 20 parts diesel oil, 2 parts anionic fatty acid soap, 1 part stearic acid, 3 parts bentonite, 8 parts calcium chloride solution, 3 parts oil-soluble phenolic resin, 1 part calcium oxide, 1 part calcium carbonate, 0.5 parts nano silica, 0.5 parts phenolic resin, and 30 parts barite.

[0052] The above-mentioned alkane derivative oil-based base fluid includes the following components by weight: 98 parts alkane derivative distillate oil, 1 part polyα-olefin pour point depressant, and 1 part D-limonene.

[0053] Example 3 A drilling fluid based on an alkane derivative oil-based base fluid, the preparation method of which includes the following steps: Asphalt is pretreated by desalting and dehydrating to remove impurities. It is then heated in a furnace at 750°C. Different fractions are obtained through atmospheric and vacuum distillation to yield alkane derivative oils. The first 40% of the distillate is light oil. Poly(α-olefin) pour point depressant and D-limonene are then added sequentially, and the mixture is stirred at 1200 rpm for 40 min at 50°C to obtain an alkane derivative oil-based base liquid. Diesel fuel, anionic fatty acid soap, and stearic acid are added to the base liquid, and the mixture is stirred at 10000 rpm for 10 min. Bentonite is then added and stirred at 10000 rpm for 15 min to ensure thorough dispersion. A calcium chloride solution (20 wt%) is added and stirred at 12000 rpm for 20 min to form a water-in-oil emulsion system. Oil-soluble phenolic resin is then added. After adding resin, stir at 12000 rpm for 20 min. Then add calcium oxide and stir at 12000 rpm for 20 min. Next, add phenolic resin and stir at 12000 rpm for 20 min. Then add calcium carbonate and stir at 12000 rpm for 20 min. Finally, add nano-silica and stir at 12000 rpm for 20 min. Add barite and stir at 10000 rpm for 30 min. Adjust the density of the alkane derivative oil-based drilling fluid to 1.7 g / cm³. 3 Drilling fluids based on alkane derivative oil-based base fluids are obtained.

[0054] The drilling fluid based on alkane derivative oil-based base fluid mentioned above comprises the following components by weight: 40 parts alkane derivative oil-based base fluid, 40 parts diesel oil, 2 parts anionic fatty acid soap, 1 part stearic acid, 1.5 parts bentonite, 10 parts calcium chloride solution, 0.5 parts oil-soluble phenolic resin, 1 part calcium oxide, 2 parts calcium carbonate, 1 part nano silica, 1 part phenolic resin, and 30 parts barite.

[0055] The above-mentioned alkane derivative oil-based base fluid includes the following components by weight: 98 parts alkane derivative distillate oil, 1 part polyα-olefin pour point depressant, and 1 part D-limonene.

[0056] Example 4 A drilling fluid based on an alkane derivative oil-based base fluid, the preparation method of which includes the following steps: Shale oil and oil sands were pretreated in a 1:1 mass ratio. After desalting and dehydration to remove impurities, the oil was heated in a furnace at 750°C. Different fractions were obtained through atmospheric and vacuum distillation to yield alkane derivative oils. The first 50% of the distillate was lightly processed. Poly(α-olefin) pour point depressant and D-limonene were then added sequentially, and the mixture was stirred at 1000 rpm for 30 min at 60°C to obtain an alkane derivative oil-based base liquid. Diesel fuel, quaternary ammonium salt, and octadecyl alcohol were added to the base liquid, and the mixture was stirred at 10000 rpm for 10 min. Bentonite was then added and stirred at 10000 rpm for 15 min to ensure thorough dispersion. A 20 wt% calcium chloride solution was added and stirred at 12000 rpm for 20 min to form a water-in-oil emulsion system. Oil-soluble phenolic resin was then added. After adding grease, stir at 12000 rpm for 20 min. Then add calcium oxide and stir at 12000 rpm for 20 min. Next, add phenolic resin and stir at 12000 rpm for 20 min. Then add calcium carbonate and stir at 12000 rpm for 20 min. Finally, add nano-silica and stir at 12000 rpm for 20 min. Add barite and stir at 10000 rpm for 30 min. Adjust the density of the alkane derivative oil-based drilling fluid to 1.7 g / cm³. 3 Drilling fluids based on alkane derivative oil-based base fluids are obtained.

[0057] The drilling fluid based on alkane derivative oil-based base fluid mentioned above comprises the following components by weight: 25 parts alkane derivative oil-based base fluid, 60 parts diesel oil, 1 part quaternary ammonium salt, 0.5 parts octadecyl alcohol, 2 parts bentonite, 7 parts calcium chloride solution, 1 part oil-soluble phenolic resin, 1.5 parts calcium oxide, 1 part calcium carbonate, 0.5 parts nano silica, 0.5 parts phenolic resin, and 30 parts barite.

[0058] The above-mentioned alkane derivative oil-based base fluid includes the following components by weight: 98 parts alkane derivative distillate oil, 1 part polyα-olefin pour point depressant, and 1 part D-limonene.

[0059] Example 5 A drilling fluid based on an alkane derivative oil-based base fluid, the preparation method of which includes the following steps: Shale oil, oil sands, and asphalt were pretreated in a mass ratio of 2:1:1. After desalting and dehydration to remove impurities, the oil was heated in a furnace at 750°C. Different fractions were obtained through atmospheric and vacuum distillation to yield alkane derivative oils. These alkane derivative oils had a distillation range of the first 50% of the light distillate. Then, poly-α-olefin pour point depressant and D-limonene were added sequentially, and the mixture was stirred at 1000 rpm for 30 min at 60°C to obtain an alkane derivative oil-based base liquid. Diesel fuel, anionic fatty acid soap, and stearic acid were added to the alkane derivative oil-based base liquid, and the mixture was stirred at 10000 rpm for 10 min. Bentonite was then added and stirred at 10000 rpm for 15 min to ensure thorough dispersion. A calcium chloride solution (20 wt%) was added and stirred at 12000 rpm for 20 min to form a water-in-oil emulsion system. Finally, oil-soluble phenolic resin was added. After adding resin, stir at 12000 rpm for 20 min. Then add calcium oxide and stir at 12000 rpm for 20 min. Next, add phenolic resin and stir at 12000 rpm for 20 min. Then add calcium carbonate and stir at 12000 rpm for 20 min. Finally, add nano-silica and stir at 12000 rpm for 20 min. Add barite and stir at 10000 rpm for 30 min. Adjust the density of the alkane derivative oil-based drilling fluid to 1.7 g / cm³. 3 Drilling fluids based on alkane derivative oil-based base fluids are obtained.

[0060] The drilling fluid based on alkane derivative oil-based base fluid mentioned above comprises the following components by weight: 10 parts alkane derivative oil-based base fluid, 70 parts diesel oil, 3 parts anionic fatty acid soap, 0.5 parts stearic acid, 1.5 parts bentonite, 8 parts calcium chloride solution, 3 parts oil-soluble phenolic resin, 1 part calcium oxide, 1 part calcium carbonate, 0.5 parts nano silica, 1.5 parts phenolic resin, and 30 parts barite.

[0061] The above-mentioned alkane derivative oil-based base fluid includes the following components by weight: 80 parts alkane derivative distillate oil, 1 part polyα-olefin pour point depressant, and 1 part D-limonene.

[0062] Example 6 A drilling fluid based on an alkane derivative oil-based base fluid, the preparation method of which includes the following steps: Shale oil is pretreated by desalting and dehydrating to remove impurities. It is then heated in a furnace at 750°C. Different fractions are obtained through atmospheric and vacuum distillation to yield alkane derivative oils. The first 30% of the oil is considered a light distillate. Maleic anhydride copolymer pour point depressant and citric acid are then added sequentially, and the mixture is stirred at 1100 rpm for 35 min at 55°C to obtain an alkane derivative oil-based base fluid. Barite is added to this base fluid, and the mixture is stirred at 8000 rpm for 40 min to adjust the density of the alkane derivative oil-based drilling fluid to 1.6 g / cm³. 3 Drilling fluids based on alkane derivative oil-based base fluids are obtained.

[0063] The drilling fluid based on alkane derivative oil-based base fluid mentioned above comprises the following components by weight: 0.1 parts alkane derivative oil-based base fluid, 0.1 parts lubricant, 0.1 parts primary emulsifier, 0.1 parts secondary emulsifier, 0.1 parts organo-earth, 0.1 parts calcium chloride solution, 0.1 parts loss reducer, 0.1 parts calcium oxide, 0.1 parts calcium carbonate, 0.1 parts nano-plugging agent, 0.1 parts film-forming plugging agent, and 30 parts barite.

[0064] The above-mentioned alkane derivative oil-based base liquid includes the following components in parts by weight: 0.1 parts alkane derivative distillate oil, 0.1 parts pour point depressant, and 0.1 parts plant deodorizer.

[0065] Example 7 A drilling fluid based on an alkane derivative oil-based base fluid, the preparation method of which includes the following steps: Asphalt is pretreated by desalting and dehydrating to remove impurities. It is then heated in a furnace at 750°C. Different fractions are obtained through atmospheric and vacuum distillation to yield alkane derivative oils. These alkane derivative oils have a distillation range of the first 80% of the light distillate. Poly(α-olefin) pour point depressant and malic acid are then added sequentially, and the mixture is stirred at 1200 rpm for 40 min at 60°C to obtain an alkane derivative oil-based base liquid. Diesel fuel, quaternary ammonium salt, and octadecyl alcohol are added to the alkane derivative oil-based base liquid, and the mixture is stirred at 12000 rpm for 15 min. Bentonite is then added and stirred at 12000 rpm for 10 min to ensure thorough dispersion. A calcium chloride solution (25 wt%) is added and stirred at 10000 rpm for 20 min to form a water-in-oil emulsion system. Oil-soluble phenolic resin is then added. After adding resin, stir at 10000 rpm for 15 min. Then add calcium oxide and stir at 10000 rpm for 15 min. Next, add epoxy resin and stir at 10000 rpm for 15 min. Then add calcium carbonate and stir at 10000 rpm for 15 min. Finally, add nano-calcium carbonate and stir at 10000 rpm for 15 min. Add barite and stir at 9000 rpm for 35 min. Adjust the density of the alkane derivative oil-based drilling fluid to 1.7 g / cm³. 3 Drilling fluids based on alkane derivative oil-based base fluids are obtained.

[0066] The drilling fluid based on alkane derivative oil-based base fluid mentioned above comprises the following components by weight: 100 parts alkane derivative oil-based base fluid, 70 parts diesel oil, 5 parts quaternary ammonium salt, 5 parts octadecyl alcohol, 5 parts bentonite, 20 parts calcium chloride solution, 5 parts oil-soluble phenolic resin, 5 parts calcium oxide, 5 parts calcium carbonate, 5 parts nano calcium carbonate, 5 parts epoxy resin, and 80 parts barite.

[0067] The above-mentioned alkane derivative oil-based base liquid comprises the following components by weight: 100 parts alkane derivative distillate oil, 1 part poly-α-olefin pour point depressant, and 1 part malic acid.

[0068] Comparative Example 1 A drilling fluid, the preparation method of which includes the following steps: After adding barite to the diesel fuel, stir at 10,000 rpm for 30 minutes to adjust the drilling fluid density to 1.7 g / cm³. 3 , and obtain drilling fluid.

[0069] The drilling fluid described above comprises the following components by weight: 100 parts diesel oil and 30 parts barite.

[0070] Experimental Example 1 The performance parameters of the drilling fluids based on alkane derivative oil-based base fluids prepared in Examples 1-6 and the drilling fluid prepared in Comparative Example 1 were tested, and the results are shown in Table 1.

[0071] Table 1 Performance Parameter Comparison Table

[0072] Table 1 shows that as the base oil substitution rate increases, the dynamic shear force generally meets the usage requirements within the operating range, while the viscosity-shear ratio shows a significant upward trend, the demulsification voltage shows a significant upward trend, and the high-temperature, high-pressure filtration loss decreases significantly. Oil-based drilling fluids made from all-diesel-based and all-alkane derivative-based base oils exhibit significant differences in rheology, while the demulsification voltage and high-temperature, high-pressure filtration loss are basically consistent. This indicates that within a certain range, alkane derivatives possess excellent thermal stability, low lubricity coefficient, and stable rheology, while also exhibiting a biodegradability rate of 80%-95%, complying with stringent global regulations.

[0073] 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 principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing drilling fluid based on alkane derivative oil-based base fluid, characterized in that, Includes the following steps: Lubricant, primary emulsifier, and secondary emulsifier are added to an alkane derivative oil-based base fluid and stirred until homogeneous. Then, organic clay is added and stirred until homogeneous. Next, calcium chloride solution is added and stirred until homogeneous. Then, a filter loss reducer is added and stirred until homogeneous. Finally, calcium oxide is added and stirred until homogeneous. Then, a film-forming plugging agent is added and stirred until homogeneous. Then, calcium carbonate is added and stirred until homogeneous. Finally, a nano-plugging agent is added and stirred until homogeneous. Finally, barite is added to obtain a drilling fluid based on an alkane derivative oil-based base fluid.

2. The method for preparing drilling fluid based on alkane derivative oil-based base fluid as described in claim 1, characterized in that, The drilling fluid based on alkane derivative oil-based base fluid comprises the following components by weight: 0.1-100 parts alkane derivative oil-based base fluid, 0-100 parts lubricant, 0.1-5 parts primary emulsifier, 0.1-5 parts secondary emulsifier, 0.1-5 parts organo-earth, 0.1-20 parts calcium chloride solution, 0.1-5 parts loss reducer, 0.1-5 parts calcium oxide, 0.1-5 parts calcium carbonate, 0.1-5 parts nano-plugging agent, 0.1-5 parts film-forming plugging agent, and 30-80 parts barite.

3. The method for preparing drilling fluid based on alkane derivative oil-based base fluid as described in claim 1 or 2, characterized in that, The drilling fluid based on alkane derivative oil-based base fluid comprises the following components by weight: 50 parts alkane derivative oil-based base fluid, 50 parts lubricant, 2 parts primary emulsifier, 1 part secondary emulsifier, 2 parts organic clay, 6 parts calcium chloride solution, 3 parts loss reducer, 1 part calcium oxide, 3 parts calcium carbonate, 1 part nano-plugging agent, 1 part film-forming plugging agent, and 30 parts barite.

4. The method for preparing drilling fluid based on alkane derivative oil-based base fluid as described in any one of claims 1-3, characterized in that, The alkane derivative oil-based base liquid is prepared by the following method: the feed oil is pretreated, heated, and then divided into different fractions to obtain alkane derivative distillate oil. Then, pour point depressant and plant deodorizing agent are added in sequence and stirred evenly to obtain alkane derivative oil-based base liquid.

5. The method for preparing drilling fluid based on alkane derivative oil-based base fluid as described in claim 4, characterized in that, The feedstock oil is at least one of shale oil, oil sands, extra-heavy oil, and bitumen.

6. The method for preparing drilling fluid based on alkane derivative oil-based base fluid as described in claim 4, characterized in that, The alkane derivative oil-based base liquid comprises the following components by weight: 0.1-100 parts of alkane derivative distillate oil, 0.1-1 parts of pour point depressant, and 0.1-1 parts of plant deodorizer, wherein the distillate oil has a distillation range of 75-85%.

7. The method for preparing drilling fluid based on alkane derivative oil-based base fluid as described in claim 6, characterized in that, The pour point depressant is a poly-α-olefin pour point depressant or / and a maleic anhydride copolymer pour point depressant.

8. The method for preparing drilling fluid based on alkane derivative oil-based base fluid as described in any one of claims 1-3, characterized in that, The primary emulsifier is at least one of anionic fatty acid soap, alkylphenol polyoxyethylene ether, quaternary ammonium salt, and betaine.

9. The method for preparing drilling fluid based on alkane derivative oil-based base fluid as described in any one of claims 1-3, characterized in that, The co-emulsifier is stearic acid and / or octadecyl alcohol.

10. A drilling fluid based on an alkane derivative oil-based base fluid prepared by the method for preparing drilling fluid based on an alkane derivative oil-based base fluid as described in any one of claims 1-9.

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