A reagent for breaking gel of oilfield water-based drilling wastewater and its application

Abstract

The present invention discloses a reagent for breaking gel in oilfield water-based drilling wastewater and its application. The reagent for breaking gel in the present invention is composed of a pH regulator and a metal organic framework material. The application method of the reagent for breaking gel in drilling wastewater of the present invention comprises the following steps: (1) adding a pH regulator to the oilfield drilling wastewater and stirring it evenly. (2) adding a metal organic framework material to the drilling wastewater obtained in step (1), stirring and rapidly settling it to achieve a breaking gel effect. (3) using a plate and frame filter press to separate solid and liquid, and the filtered filtrate is treated and then used as drilling fluid for reuse, so as to achieve the purpose of reuse. The present invention relates to the technical field of drilling wastewater treatment. The reagent for breaking gel in oilfield water-based drilling wastewater and its application, the breaker of the present invention breaks gel thoroughly, has high breaking efficiency, is easy to separate solid and liquid after breaking gel, the solid phase pH can meet environmental protection requirements, the separated liquid can be fully reused, meets green environmental protection requirements, and reduces production costs.

Description

Technical Field

[0001] The invention relates to the technical field of drilling wastewater treatment, in particular to a reagent for gel breaking of oilfield water-based drilling wastewater and an application thereof. Background Art

[0002] Drilling fluid is an essential material in modern oil and gas well drilling, playing a crucial role in stabilizing the wellbore, cooling and lubricating the drill bit, and encapsulating drilling debris. Water-based drilling fluid accounts for 60% to 70% of all oil drilling operations. In recent years, with the development of environmentally friendly drilling practices and the introduction of the new Environmental Protection Law, many regions are requiring that drilling waste be disposed of "off the ground." Drilling wastewater, after solid-liquid separation, can be used for landfill or brick making. The separated liquid can then be further treated to meet discharge standards or reused in drilling fluid, thereby reducing environmental pollution.

[0003] However, the current method for breaking the gel of water-based drilling fluid mainly adopts the combination of inorganic metal coagulants and organic flocculants. After the particles of the drilling wastewater system are destabilized, they are aggregated in the solid phase of the system through flocculation and sedimentation, which can remove most of the suspended matter and some soluble substances in the upper separation liquid.

[0004] The main problems are as follows: 1. Drilling wastewater is highly stable, but the efficiency of gel breaking is low, and the separated liquid after gel breaking contains many impurities; 2. Drilling wastewater flocculation is difficult, the dosage of reagents is large, and the treatment cost is high; 3. The calcium and aluminum-based breakers commonly used for gel breaking result in high concentrations of high-valent metal ions in the separated liquid after gel breaking, making it difficult to reuse.

[0005] Therefore, it is necessary to conduct in-depth research on oilfield drilling wastewater gel breaking technology. Summary of the Invention

[0006] (1) Technical problems solved

[0007] In view of the shortcomings of the existing technology, the present invention provides a reagent for breaking gel of oilfield water-based drilling wastewater and its application, which effectively solves the current technical problems of difficult gel breaking and solid-liquid separation of drilling wastewater.

[0008] (2) Technical solution

[0009] To achieve the above objectives, the present invention is implemented through the following technical solutions: a reagent for breaking gel of oilfield water-based drilling wastewater, comprising a pH regulator and a metal organic framework material; the mass volume ratio of the pH regulator to the oilfield drilling wastewater is 0.4-0.8 kg / m 3 The mass volume ratio of the metal organic framework material to the oil field drilling wastewater is 0.5-1kg / m 3 .

[0010] Preferably, the preparation process of the metal organic framework material MIL-101 (Fe) is specifically as follows:

[0011] T1. Dissolve FeCl3·6H2O and 2-aminoterephthalic acid in N,N-dimethylformamide and sonicate for 10-30 min to completely dissolve the solids.

[0012] T2. The mixed solution was transferred to an autoclave and reacted at high temperature for 20 hours. A dark orange solid was obtained by centrifugation. The solid was washed and purified with hot ethanol for multiple times and then dried.

[0013] Preferably, the high temperature condition in step T2 is 110-150°C.

[0014] Preferably, the drying temperature in step T2 may be 50-90°C.

[0015] The present invention also provides an application of a reagent for breaking gel in oilfield water-based drilling wastewater, which specifically comprises the following steps:

[0016] E1. Neutralization and destabilization: add citric acid to the drilling wastewater to adjust the pH to neutral and initially destabilize the drilling wastewater system;

[0017] E2, adhesion co-precipitation: add metal organic framework materials to the initially destabilized drilling wastewater, first stir at high speed to disperse it and adhere to the particle surface, then reduce the speed to allow flocs to settle;

[0018] E3. Solid-liquid separation: put the drilling wastewater that has undergone coagulation and sedimentation into a plate and frame filter press for filtration or into a centrifuge for centrifugal treatment to complete solid-liquid separation.

[0019] Preferably, in step E3, the solid phase is transported out for landfill, and the separated liquid is used for remixing the drilling fluid after simple treatment, thereby achieving the purpose of recycling.

[0020] (3) Beneficial effects

[0021] The present invention provides a reagent for breaking gel in oilfield water-based drilling wastewater and its application. Compared with the existing technology, it has the following advantages:

[0022] (1) The reagent and application for breaking gel in oilfield water-based drilling wastewater. The breaker of the present invention uses a small amount of material, is safe and easy to obtain, and produces a solid phase pH between 6 and 9, which meets the emission requirements. The metal organic framework material MIL-101 used has high chemical stability in water and organic solvents and is easy to handle. It is an excellent treatment material and will not increase the metal ion concentration of the drilling wastewater system. The separated liquid after breaking gel by this method can be reused.

[0023] (2) The reagent and application for breaking gel of oilfield water-based drilling wastewater is simple in material and has fewer breaking steps. Compared with traditional inorganic metal coagulants, the separated liquid after breaking gel does not increase the concentration of metal ions, which is conducive to the reuse of the separated liquid and the re-mixing of drilling fluid, further reducing the pollution problem to the environment and reducing the production cost. + The negative charge on the particle surface in the neutralization system regulates the zeta potential, and the metal-organic framework's adsorption and flocculation effects combine to achieve gel breaking. This not only increases water yield but also saves time. Furthermore, the separated liquid after gel breaking can be recycled and reused in drilling fluids. The entire gel breaking method is simple, fast, low-cost, and has excellent economic and environmental value. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the original drilling wastewater situation of the present invention;

[0025] Figure 2 This is a schematic diagram of wastewater treated with the gel-breaking reagent prepared in Example 1 of the present invention;

[0026] Figure 3 This is a schematic diagram of the wastewater after being treated with the reagent in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings and attached tables in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0028] For original drilling wastewater, please refer to Figure 1 The present invention provides a technical solution: a reagent and application for breaking gel in oilfield water-based drilling wastewater, specifically including the following embodiments:

[0029] Example 1

[0030] The specific method for preparing MIL-101(Fe) in this embodiment is as follows:

[0031] 0.6622 g of FeCl₃·6H₂O and 0.2246 g of 2-aminoterephthalic acid were dissolved in 15 mL of N,N-dimethylformamide and sonicated for 15 minutes to completely dissolve the solid. The mixed solution was transferred to an autoclave and reacted at 110°C for 20 hours. Centrifugation yielded a dark orange solid, which was then washed three times with hot ethanol and dried at 70°C to yield MIL-101(Fe).

[0032] Step 1: Add 0.4 kg / m 3 Citric acid, pH 7.11 after stirring

[0033] In the second step, 0.5 kg / m 3 The prepared MIL-101(Fe) was stirred at 400r / min for 10 minutes and then allowed to stand for 2 hours. The gel breaking effect was obvious, the water yield was 73%, and the bottom flocs were dense and stable.

[0034] The third step is to separate the solid and liquid. Figure 2 .

[0035] The gel breaking condition of Example 1 and the determination of the indexes of the separated liquid after gel breaking are shown in Table 1.

[0036] Example 2

[0037] The specific method for preparing MIL-101(Fe) in this embodiment is as follows:

[0038] 0.6622 g of FeCl₃·6H₂O and 0.2246 g of 2-aminoterephthalic acid were dissolved in 15 mL of N,N-dimethylformamide and sonicated for 15 minutes to completely dissolve the solid. The mixed solution was transferred to an autoclave and reacted at 110°C for 20 hours. Centrifugation yielded a dark orange solid, which was then washed three times with hot ethanol and dried at 70°C to yield MIL-101(Fe).

[0039] Step 1: Add 0.4 kg / m 3 Citric acid, pH 7.08 after stirring

[0040] In the second step, 1 kg / m 3 The prepared MIL-101(Fe) was stirred at 400r / min for 10 minutes and then allowed to stand for 2 hours. The gel breaking effect was obvious, the water yield was 75%, and the bottom flocs were dense and stable.

[0041] The third step is solid-liquid separation.

[0042] The gel breaking condition of Example 2 and the determination of the indexes of the separated liquid after gel breaking are shown in Table 1.

[0043] Example 3

[0044] The specific method for preparing MIL-101(Fe) in this embodiment is as follows:

[0045] 0.6622 g of FeCl₃·6H₂O and 0.2246 g of 2-aminoterephthalic acid were dissolved in 15 mL of N,N-dimethylformamide and sonicated for 15 minutes to completely dissolve the solid. The mixed solution was transferred to an autoclave and reacted at 110°C for 20 hours. Centrifugation yielded a dark orange solid, which was then washed three times with hot ethanol and dried at 70°C to yield MIL-101(Fe).

[0046] Step 1: Add 0.6 kg / m 3 Citric acid, pH 5.43 after stirring

[0047] In the second step, 1 kg / m 3 The prepared MIL-101(Fe) was stirred at 400r / min for 10 minutes and then allowed to stand for 2 hours. The gel breaking effect was obvious, the water yield was 77%, and the bottom flocs were dense and stable.

[0048] The third step is solid-liquid separation.

[0049] The gel breaking condition of Example 3 and the determination of the indexes of the separated liquid after gel breaking are shown in Table 1.

[0050] Comparative Example 1

[0051] In order to illustrate the gel breaking effect of the gel breaker of the present invention, the inventors conducted the following comparative experiment. The experimental conditions were the same as those in Example 1, except that the gel breakers were different. In the comparative experiment, calcium chloride, a common inorganic flocculant, was used alone as the gel breaker to compare the gel breaking effects.

[0052] Step 1: Add 0.4 kg / m 3 Citric acid, pH 7.09 after stirring

[0053] In the second step, 5 kg / m 3 Calcium chloride was stirred thoroughly at 400 rpm for 10 minutes and then allowed to stand for 2 hours. Significant gel breaking was observed, with a water yield of 62%. However, shaking revealed that the flocs at the bottom were fine and easily resuspended, making solid-liquid separation difficult.

[0054] The third step is to separate the solid and liquid by centrifugation. Figure 3 .

[0055] The gel breaking condition of Comparative Example 1 and the determination of the indexes of the separated liquid after gel breaking are shown in Table 1.

[0056] Table 1

[0057]

[0058]

[0059] In Example 1, the gel breaking is effectively achieved by adding citric acid and MIL-101 (Fe), and the metal ion concentration of the supernatant is not high; in Example 2, the dosage of MIL-101 (Fe) is changed, and the dosage further reduces the SS concentration in the supernatant, the supernatant is clearer, and the ion concentration is not significantly changed; in Example 3, the dosage of citric acid is changed compared with Example 2, and the pH is further reduced, which has little effect on the water yield and SS of the supernatant, but increases the concentration of metal ions released in the system; Example 1 has a certain effect on the gel breaking of drilling wastewater compared with Comparative Example 1, but the water yield and SS reduction degree of Example 1 are slightly better, and the dosage of Comparative Example 1 is ten times that of Example 1. The drilling wastewater separation liquid with the addition of inorganic flocculant contains a large amount of metal ions, which causes metal ion contamination to the liquid phase after gel breaking and is not easy to reuse; the metal ion concentration in the drilling wastewater separation liquid with the addition of metal organic framework material is at a normal level, and the separation liquid is less polluted.

[0060] In summary, the breaker of the present invention uses a small amount of materials, is safe and easy to obtain, and produces a solid phase pH between 6 and 9, which meets emission requirements. The metal organic framework material MIL-101 used is easy to handle due to its high chemical stability in water and organic solvents, making it an excellent treatment material. The synthesized breaker uses simple materials and has fewer gel breaking steps. Compared with traditional inorganic metal flocculants, the separated liquid after gel breaking does not increase the metal ion concentration, which is conducive to the reuse of the separated liquid, further reducing environmental pollution problems, and reducing production costs. H ionized by citric acid in water + The negative charge on the particle surface in the neutralization system regulates the zeta potential, and the metal-organic framework's adsorption and flocculation effects combine to achieve gel breaking. This not only increases water yield but also saves time. Furthermore, the separated liquid after gel breaking can be recycled and reused in drilling fluids. The entire gel breaking method is simple, fast, low-cost, and has excellent economic and environmental value.

[0061] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0062] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0063] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is limited by the appended claims and their equivalents.

Claims

1. A reagent for breaking gel in oilfield water-based drilling wastewater, characterized by: It includes pH regulator and metal organic framework material; the mass volume ratio of pH regulator to oilfield drilling wastewater is 0.4-0.8kg / m 3 The mass volume ratio of the metal organic framework material to the oil field drilling wastewater is 0.5-1kg / m 3 ; The preparation process of the metal organic framework material is specifically as follows: T1. Dissolve FeCl3·6H2O and 2-aminoterephthalic acid in N,N-dimethylformamide and sonicate for 10-30 min to completely dissolve the solids. T2. The solution after ultrasonic treatment in step T1 was transferred to an autoclave and reacted at high temperature for 20 hours. A dark orange solid was obtained by centrifugation, which was washed and purified with hot ethanol for multiple times and then dried.

2. The reagent for breaking gel of oilfield water-based drilling wastewater according to claim 1, characterized in that: The high temperature condition in step T2 is 110-150°C.

3. The reagent for breaking gel of oilfield water-based drilling wastewater according to claim 1, characterized in that: The drying temperature in step T2 is 50-90°C.

4. An application of the reagent for breaking gel in oilfield water-based drilling wastewater according to any one of claims 1 to 3, characterized in that: The specific steps include: E1. Neutralization and destabilization: add citric acid to the drilling wastewater to adjust the pH to neutral and initially destabilize the drilling wastewater system; E2, adhesion co-precipitation: add metal organic framework materials to the initially destabilized drilling wastewater, first stir at high speed to disperse it and adhere to the particle surface, then reduce the speed to allow flocs to settle; E3. Solid-liquid separation: put the drilling wastewater that has undergone coagulation and sedimentation into a plate and frame filter press for filtration or into a centrifuge for centrifugal treatment to complete solid-liquid separation.

5. The use of a reagent for breaking gel in oilfield water-based drilling wastewater according to claim 4, characterized in that: In step E3, the solid phase is transported out for landfill, and the separated liquid is used for remixing the drilling fluid after simple treatment, thereby achieving the purpose of recycling.

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