Environmentally friendly drilling fluid prepared using wood ash and preparation method thereof

Abstract

The present invention provides an environmentally friendly drilling fluid prepared using wood ash and a preparation method thereof, belonging to the field of oil extraction technology. The environmentally friendly drilling fluid is prepared using wood ash, polyols, and modified coconut oil. The high-molecular-weight particles in the wood ash exhibit a certain fluid loss reduction effect; the polyols not only have good inhibitory properties but are also non-toxic, easily biodegradable, and cause minimal damage to oil reservoirs; the modified coconut oil not only has lubricity but is also non-toxic and easily degradable. By combining the above-mentioned multiple environmentally friendly treatment agents, an environmentally friendly drilling fluid with excellent comprehensive performance can be obtained, with a biotoxicity value EC50 reaching 25,000 mg / L, meeting drilling production needs while effectively utilizing waste and protecting the environment.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum extraction, and particularly relates to an environmentally friendly drilling fluid prepared from wood ash and a preparation method thereof. Background Art

[0002] Drilling fluid affects the quality and efficiency of drilling projects. Good rheological properties, inhibition, lubricity, temperature resistance and other properties contribute to the safe conduct of drilling operations. With the rapid development of my country's economy, environmental problems have become increasingly prominent. The country has become increasingly strict with environmental protection, and environmentally friendly drilling fluids have also received much attention from scientific and technological workers and oilfield companies. The water-based drilling fluids currently used in drilling projects mainly include polymer drilling fluids, polysulfone drilling fluids and other systems. The treatment agents in these systems are mostly toxic and difficult to degrade, and have a certain destructive effect on the formation. Today's environmental issues are one of the key problems that need to be solved in the exploration and development of oil and gas resources. Reducing drilling fluid pollution is the top priority for solving environmental pollution in oil and gas exploration and development. Therefore, the development of new environmentally friendly drilling fluid technologies is of vital importance.

[0003] Patent "An Environmentally Friendly Drilling Fluid" (CN201610787104.0) introduces an environmentally friendly drilling fluid. The environmentally friendly drilling fluid includes: The present invention provides an environmentally friendly drilling fluid, including a natural polymer strong coating inhibitor, a natural polymer fluid loss reducer, a polyol, a non-fluorescent white asphalt anti-slump agent, a viscosity reducer, an oil layer protection temporary plugging agent and other environmentally friendly treatment agents. The system is mainly composed of environmentally friendly treatment agents such as natural polymers. It is non-biotoxic and has excellent inhibitory, anti-slump and lubricity. Through the technical advantages of the composite inhibition, anti-slump, lubrication and temporary plugging of the above-mentioned multiple environmentally friendly treatment agents, it has excellent performance, is easy to maintain and handle, and has strong inhibitory ability. It not only meets the production needs of shallow wells and medium-deep wells, but also effectively protects the environment.

[0004] The patent "A Naturally Degradable Environmentally Friendly Drilling Fluid" (CN201911188133.5) describes an environmentally friendly drilling fluid. The fluid contains: 3.0%-7.0% shale inhibitor, 1.0%-3.0% natural anti-collapse agent, 1.0%-5.0% natural plugging agent, 0.3%-0.5% natural viscosity enhancer, 1.5%-3% natural fluid loss additive, 0.5%-4.0% lubricant, 0.1%-0.3% polyhydroxymethylhydroxyethylsiloxane, 0.02%-0.07% antioxidant, and the balance is water. The present invention can be applied to the safe drilling and completion construction of exploration wells, special process wells and horizontal wells in the Changqing area. It has six major functions: stabilizing the well wall, preventing and plugging leaks, carrying and suspending sand, purifying the wellbore, protecting the reservoir and protecting the environment. It is non-biotoxic, non-chemically toxic, biodegradable and environmentally friendly. It has strong anti-collapse ability and good sealing effect, and can effectively reduce the collapse ability of the formation. The mud cake is smooth and dense, similar to a membrane, with good lubricity, and has little damage to low-porosity, low-permeability and low-abundance oil reservoirs. The formulation and slurry preparation process are simple and easy.

[0005] The patent "An Environmentally Friendly Calcium Nitrate Drilling Fluid and Preparation Method" (CN201410707100.8) describes an environmentally friendly drilling fluid. The environmentally friendly drilling fluid comprises: 3-5% by weight of an inorganic flocculant, 0.3-1% of a viscosity enhancer, 0.5-1.0% of a fluid loss reducer, 0.1-0.3% of an alkalinity controller, 0.03-0.1% of a preservative, and the remainder being water. The drilling fluid exhibits low viscosity and high shear strength, good fluidity, strong resistance to gypsum contamination, high solids capacity, a thin and tough mud cake, easily adjustable rheological properties, moderate flocculation and stability, and outstanding anti-collapse effects. This drilling fluid does not contain wood ash, which is completely different from the core content of the present invention.

[0006] The paper "An Environmentally Friendly High-Temperature Drilling Fluid Technology" introduces an environmentally friendly drilling fluid. This fluid comprises the development and synthesis of novel environmentally friendly high-temperature resistant viscosity enhancer BZ-ZNJ, environmentally friendly high-temperature resistant fluid loss reducer BZ-KGJ, and other treatment agents, compounded with other environmentally friendly treatment agents to form an environmentally friendly high-temperature resistant drilling fluid system. This system exhibits temperature resistance up to 230°C, controllable rheological properties at 230°C, viscosity shear strength that meets construction requirements, salt resistance reaching saturation, calcium resistance reaching 1.5%, and clay encroachment resistance reaching 10%. The drilling fluid has an EC50 of greater than 30,000 mg / L, making it non-toxic, and its metal ion content is below standard values, meeting environmental protection requirements.

[0007] The paper "Research on Desulfonated Environmentally Friendly Drilling Fluid" describes an environmentally friendly drilling fluid, which includes: a desulfonated environmentally friendly drilling fluid developed using an environmentally friendly fluid loss reducer, and its rheological properties, fluid loss reduction performance, salt and calcium pollution resistance, temperature resistance, inhibition performance, and environmental performance were evaluated. The evaluation results show that at a density of 1.80g / cm 3It has good rheological properties, water loss wall-forming properties and lubricity at temperatures within 180°C and below 180°C, and its performance is stable. It has strong inhibitory properties and can effectively prevent the hydration expansion and dispersion of shale, prevent formation slurrying and well wall collapse. It has good resistance to salt and gypsum pollution. Its biological toxicity meets the emission standards and it has good biodegradability. It meets the needs of drilling and geological logging.

[0008] In summary, existing environmentally friendly drilling fluids are constructed with natural polymers as the core material, resulting in high overall construction costs. Based on this, the present invention innovatively uses wood ash as the raw material to prepare environmentally friendly drilling fluid, achieving both environmental and economic benefits and promising application prospects. Summary of the Invention

[0009] The present invention addresses the problems of the prior art and provides an environmentally friendly drilling fluid prepared using wood ash and a preparation method thereof. The environmentally friendly drilling fluid is prepared using wood ash, polyols, and modified coconut oil. The high-molecular-weight particles in the wood ash exhibit a certain fluid loss reduction effect; the polyols not only have good inhibitory properties but are also non-toxic and biodegradable, causing minimal damage to oil reservoirs; and the modified coconut oil not only has lubricity but is also non-toxic and easily degradable. By combining these multiple environmentally friendly treatment agents, an environmentally friendly drilling fluid with excellent overall performance can be obtained, with a biotoxicity value (EC50) of up to 25,000 mg / L. This fluid not only meets drilling production needs but also effectively protects the environment through waste utilization.

[0010] To achieve the above objectives, in the first aspect, the present invention provides an environmentally friendly drilling fluid prepared using wood ash, which comprises the following raw materials in parts by weight, based on 100 parts of water: 100 parts of water, 0.05-0.5 parts of anhydrous sodium carbonate, 1-5 parts of an environmentally friendly fluid loss reducer, 0.05-0.5 parts of sodium hydroxide, 1-5 parts of an environmentally friendly inhibitor, 1-5 parts of a lubricant, and barite weighted to 1.1-1.5 g / cm 3 .

[0011] In a preferred embodiment, the environmentally friendly fluid loss agent is modified wood ash, the environmentally friendly inhibitor is polyol, and the lubricant is modified coconut oil.

[0012] In a preferred embodiment, the modified plant ash preparation method is as follows:

[0013] At room temperature, weigh a certain amount of wood ash and put it into a beaker filled with distilled water. Add diethylenetriaminepentaacetic acid dropwise while stirring. Stir for 0.5-2 hours and let it stand for 2-4 hours. Adjust the pH to 6-7 with acetic acid. Continue stirring at 70-90℃ for 1-4 hours. After the reaction is completed, put it into a drying oven for drying.

[0014] In a preferred embodiment, the mass ratio of wood ash to diethylenetriaminepentaacetic acid is (1.5-2.5):1, more preferably 2:1.

[0015] In a preferred embodiment, the polyol is selected from one or more of ethylene glycol, neopentyl glycol, and dipropylene glycol.

[0016] The environmentally friendly inhibitor is preferably a complex polyol, which has strong inhibitory properties without the need for combination with inorganic salts, is non-toxic, and is easily biodegradable.

[0017] In a preferred embodiment, the modified coconut oil is prepared by the following steps:

[0018] 1) Place a certain amount of recovered coconut oil in a three-necked flask, place it in a constant temperature water bath, raise the reaction temperature to 50-60°C, then turn on the stirring, and add a certain proportion of anhydrous ethanol dropwise while stirring, and react for 1-3 hours;

[0019] 2) Stop heating and cool appropriately until the temperature drops to 40° C., add an appropriate amount of water, continue stirring for 20 minutes, and add an appropriate amount of NaOH to adjust the pH value of the solution to neutral to obtain modified coconut oil.

[0020] In a preferred embodiment, the volume ratio of recovered coconut oil to anhydrous ethanol is (3-6):1, more preferably 5:1.

[0021] In a preferred embodiment, in step 2), the volume ratio of modified coconut oil to water is (2-4):1, more preferably 3:1.

[0022] In a second aspect, the present invention provides a method for preparing the environmentally friendly drilling fluid prepared using wood ash, comprising the following steps:

[0023] Measure seawater and place it in a slurry cup. Add anhydrous sodium carbonate, sodium hydroxide, environmentally friendly fluid loss reducer, environmentally friendly inhibitor, lubricant in sequence under high-speed stirring, then add barite and stir evenly.

[0024] In a preferred embodiment, high-speed stirring is performed at a rotation speed of 8000-15000 r / min.

[0025] The present invention has the following beneficial effects:

[0026] 1. The environmentally friendly drilling fluid of the present invention is prepared using wood ash, polyols and modified coconut oil. The high molecular weight particles in the wood ash exhibit a certain fluid loss reduction effect; the polyols not only have good inhibitory properties but are also non-toxic and easily biodegradable, causing little damage to the oil reservoir; the modified coconut oil not only has lubricity but is also non-toxic and easily degradable; through the combined use of the above-mentioned multiple environmentally friendly treatment agents, an environmentally friendly drilling fluid with excellent comprehensive performance can be obtained, with a biotoxicity value EC50 of up to 25,000 mg / L, which not only meets the needs of drilling production but also effectively protects the environment through waste utilization.

[0027] 2. The environmentally friendly drilling fluid of the present invention uses domestic waste wood ash as raw material, which can not only meet the performance of the drilling fluid, but also achieve the effect of waste utilization, and has good application and promotion prospects. DETAILED DESCRIPTION

[0028] It is worth noting that the raw materials used in the present invention are all common commercial products, and their sources are not specifically limited. The technical solution of the present invention is described below through specific examples.

[0029] Preparation Example 1 Preparation of environmentally friendly fluid loss reducer

[0030] At room temperature, a certain amount of wood ash was weighed and placed in a beaker filled with distilled water. Diethylenetriaminepentaacetic acid was added dropwise while stirring. After stirring for 1 hour, the mixture was allowed to stand for 3 hours. The pH was adjusted to 6-7 with acetic acid. The mixture was stirred continuously at 80°C for 2 hours. After the reaction was completed, the mixture was placed in a drying oven for drying to obtain an environmentally friendly filtration loss reducer modified wood ash. The mass ratio of wood ash to diethylenetriaminepentaacetic acid was 2:1, and the mass-to-volume ratio of wood ash to distilled water was 1:4 g / mL.

[0031] Preparation Example 2 Preparation of Lubricant

[0032] 1) Place a certain amount of recovered coconut oil in a three-necked flask, place it in a constant temperature water bath, raise the reaction temperature to 50°C, then turn on the stirring, and add a certain proportion of ethanol dropwise while stirring, and react for 90 minutes;

[0033] 2) Stop heating, cool appropriately, and when the temperature is maintained at about 40° C., add an appropriate amount of clean water, continue stirring for 20 minutes, and add an appropriate amount of NaOH to adjust the pH value of the solution to neutral to obtain lubricant-modified coconut oil;

[0034] The volume ratio of the recovered coconut oil to anhydrous ethanol is 5:1; and the volume ratio of the modified coconut oil to clean water in step 2) is 3:1.

[0035] Example 1

[0036] Prepare water-based drilling fluid: use a graduated cylinder to measure 400 ml of seawater and place it in a slurry cup. Add 0.8 g of anhydrous sodium carbonate, 0.8 g of sodium hydroxide, 8 g of environmentally friendly fluid loss reducer (Preparation Example 1), 12 g of environmentally friendly inhibitor (ethylene glycol), 8 g of lubricant (Preparation Example 2), and barite to 1.2 g / cm2 while stirring at a speed of 11000 r / min. 3 .

[0037] Example 2

[0038] Prepare water-based drilling fluid: 400 ml of seawater was measured with a graduated cylinder and placed in a slurry cup. 0.8 g of anhydrous sodium carbonate, 0.8 g of sodium hydroxide, 16 g of environmentally friendly fluid loss reducer (Preparation Example 1), 12 g of environmentally friendly inhibitor (neopentyl glycol), 8 g of lubricant (Preparation Example 2), and barite was added in sequence while stirring at a speed of 11000 r / min. 3 .

[0039] Example 3

[0040] Prepare water-based drilling fluid: use a graduated cylinder to measure 400 ml of seawater and place it in a slurry cup. Add 0.8 g of anhydrous sodium carbonate, 0.8 g of sodium hydroxide, 8 g of environmentally friendly fluid loss reducer (Preparation Example 1), 6 g of environmentally friendly inhibitor (dipropylene glycol), 4 g of lubricant (Preparation Example 2), and barite to 1.3 g / cm2 while stirring at a speed of 11000 r / min. 3 .

[0041] Example 4

[0042] Prepare water-based drilling fluid: Measure 400 ml of seawater with a graduated cylinder and place it in a slurry cup. Add 0.8 g of anhydrous sodium carbonate, 0.8 g of sodium hydroxide, 10 g of environmentally friendly fluid loss reducer (Preparation Example 1), 12 g of environmentally friendly inhibitor (ethylene glycol), 12 g of lubricant (Preparation Example 2), and barite to 1.35 g / cm2 while stirring at a speed of 11,000 r / min. 3 .

[0043] Comparative Example 1

[0044] Except for using wood ash as the environmentally friendly fluid loss additive, the rest is the same as Example 1.

[0045] Prepare water-based drilling fluid: Measure 400 ml of seawater with a graduated cylinder and place it in a slurry cup. Add 0.8 g of anhydrous sodium carbonate, 0.8 g of sodium hydroxide, 8 g of plant ash, 12 g of environmentally friendly inhibitor (ethylene glycol), 8 g of lubricant (Preparation Example 2), and barite to 1.2 g / cm2 while stirring at a speed of 11,000 r / min. 3 .

[0046] Comparative Example 2

[0047] Except that diethylenetriaminepentaacetic acid is used as the environmentally friendly fluid loss additive, the rest is the same as Example 1.

[0048] Prepare water-based drilling fluid: Measure 400 ml of seawater with a graduated cylinder and place it in a slurry cup. Add 0.8 g of anhydrous sodium carbonate, 0.8 g of sodium hydroxide, 8 g of diethylenetriamine pentaacetic acid, 12 g of environmentally friendly inhibitor (ethylene glycol), 8 g of lubricant (Preparation Example 2), and barite to 1.2 g / cm2 while stirring at a speed of 11000 r / min. 3 .

[0049] Test example

[0050] Examples 1-4 and Comparative Example 1 were tested using the API recommended standards. The results are shown in Table 1:

[0051] Table 1

[0052]

[0053] As can be seen from Table 1, the drilling fluids of Examples 1-4 of the present invention have a biotoxicity EC50 value of up to 25,000 mg / L, exhibit good biodegradability, and have a medium-pressure water loss as low as 4.5-5.5 ml, demonstrating excellent overall performance. Comparison of Example 1 with Comparative Examples 1 and 2 reveals that chemical modification of wood ash with diethylenetriaminepentaacetic acid exhibits a strong synergistic effect, significantly enhancing the fluid loss reduction effect of wood ash.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An environmentally friendly drilling fluid prepared using wood ash, characterized in that: Based on 100 parts of water, the following raw materials are included by weight: 100 parts of water, 0.05-0.5 parts of anhydrous sodium carbonate, 1-5 parts of environmentally friendly fluid loss reducer, 0.05-0.5 parts of sodium hydroxide, 1-5 parts of environmentally friendly inhibitor, 1-5 parts of lubricant, and barite weighted to 1.1-1.5g / cm 3； The environmentally friendly fluid loss agent is modified wood ash, the environmentally friendly inhibitor is polyol, and the lubricant is modified coconut oil; The modified plant ash preparation method is as follows: At room temperature, weigh wood ash and place it in a beaker filled with distilled water. Add diethylenetriamine pentaacetic acid dropwise while stirring. Stir for 0.5-2 hours, then let it stand for 2-4 hours. Adjust the pH to 6-7 with acetic acid. Continue stirring at 70-90°C for 1-4 hours. After the reaction is complete, place it in a drying oven for drying to obtain the product. The mass ratio of wood ash to diethylenetriaminepentaacetic acid is (1.5-2.5):

1.

2. The environmentally friendly drilling fluid according to claim 1, characterized in that: The polyol is selected from one or more of ethylene glycol, neopentyl glycol, and dipropylene glycol.

3. The environmentally friendly drilling fluid according to claim 1, characterized in that: The production steps of the modified coconut oil are as follows: 1) Place recovered coconut oil in a three-necked flask, place it in a constant temperature water bath, raise the reaction temperature to 50-60°C, then stir evenly. While stirring, add a certain proportion of anhydrous ethanol dropwise and react for 1-3 hours; 2) Stop heating and cool appropriately until the temperature drops to 40°C, add an appropriate amount of water, continue stirring for 20 minutes, and add an appropriate amount of NaOH to adjust the pH value of the solution to neutral to obtain modified coconut oil.

4. The environmentally friendly drilling fluid according to claim 3, characterized in that: The volume ratio of recovered coconut oil to anhydrous ethanol is (3-6):

1.

5. The environmentally friendly drilling fluid according to claim 4, characterized in that: In step 2), the volume ratio of modified coconut oil to clean water is (2-4):

1.

6. The method for preparing an environmentally friendly drilling fluid prepared using wood ash according to any one of claims 1 to 5, wherein: The steps include: Measure seawater and place it in a slurry cup. Add anhydrous sodium carbonate, sodium hydroxide, environmentally friendly fluid loss reducer, environmentally friendly inhibitor, lubricant in sequence at a speed of 8000-15000r / min, then add barite and stir evenly.

7. The preparation method according to claim 6, wherein Stir at high speed at 8000-15000r / min.

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