Environmentally friendly drilling fluid

Abstract

FIELD: oil industry; gas industry.SUBSTANCE: environmentally friendly drilling fluid contains, mas.%: viscosity reducer - hydroxyethylidene diphosphonic acid (HEDP) 0.1-0.49; fluid loss reducer - acrylic polymer “Гивпан” 0.34-0.81; bentonite powder “ПБМВ” 7-10; structure formation regulator - sodium chloride NaCl from more than 0 to 0.29; water - the remainder and is a clay suspension mixed first for 40 minutes at 600 rpm, and then twice more for 30 minutes at 600 rpm: once after adding Givpan and NaCl, and a second time after adding HEDP.EFFECT: expansion of technological capabilities of the drilling fluid, increasing the thermal stability of the drilling fluid, environmental friendliness, possibility of drilling oil and gas wells in areas with vulnerable soil-covering vegetation and in sea areas.1 cl, 1 tbl, 12 ex

Description

[0001] The invention relates to the oil and gas industry, namely to the drilling of oil and gas wells, to water-based drilling fluids, in particular for drilling wells in areas with vulnerable soil-covering vegetation (tundra), in sea waters (fisheries, where it is necessary to protect water bodies and marine animals from the harmful toxic effects of drilling reagents).

[0002] During the third stage of well construction, namely during drilling, chemical reagents, wastewater, and waste solutions cause significant damage to the environment, surface and groundwater, and soil cover, especially in northern conditions and offshore drilling.

[0003] Potassium and sodium chromates and dichromates, which are potassium and sodium salts of chromic and dichromic acids and are highly soluble in water, pose a particular hazard. They are designed to enhance the stabilizing ability of protective reagents, reduce the pH and viscosity of drilling fluids, and partially prevent the globalization of clay particles at elevated temperatures.

[0004] The list of hazardous chromium compounds continues with lignosulfonate chromium-containing reagents: ferrochrome lignosulfonate (FCLS) and OKZIL-SM, obtained by oxidizing calcium sulfate-alcohol stillage with chromate in an acidic environment.

[0005] A gypsum-lime drilling mud based on sodium formate is known for maintaining the integrity of a productive formation in intervals of weakly cemented rocks, in unstable clay deposits, argillites and shales (RU Patent No. 2830707, IPC C09K 8 / 08, published on July 8, 2024). The drilling mud contains: sodium formate, bactericide, starch reagent, polyanionic cellulose PAC "KhimPAK", xanthan biopolymer, Ingidol DT inhibitor composition, carbonate weighting agent - marble chips, lubricating additive, gypsum, FHLS drilling reagent, slaked lime and water.

[0006] The use of the FHLS reagent, which contains toxic sodium dichromate, is limited in the drilling fluid's application range due to environmental concerns. Its multi-component nature also limits its use, requiring high labor and time investment in the preparation process and maintaining the fluid's properties during drilling. Furthermore, increased filtration stability with increasing temperature is required.

[0007] Gel-Drill drilling fluid is a well-known product (we adopted it as a prototype - No. 2687815, IPC C09K 8 / 20, published on May 16, 2019). The drilling fluid contains: soda ash, sodium hydroxide, PBMV clay powder, FHLS viscosity reducer, BD defoamer, ANIPOL-VV high-viscosity cellulose, ANIPOL-NV low-viscosity cellulose, calcium carbonate, PCT cement, potassium hydroxide, BL-SALT lubricating additive, and water. This drilling fluid is designed to comprehensively improve inhibiting and waterproofing properties and resistance to carbon dioxide aggression.

[0008] The disadvantages of the solution include the content of an environmentally harmful additive for regulating structural and mechanical properties - FHLS, as well as its multi-component nature, which requires a lot of time and money to prepare it and maintain its properties during drilling.

[0009] The objective of the invention is to expand the environmental and technological capabilities of drilling fluid by replacing protective reagents with environmentally friendly analogs, increasing its heat resistance and reducing the costs of preparation and maintaining properties during drilling operations.

[0010] The task is achieved in that an environmentally friendly drilling fluid containing a viscosity reducer, a fluid loss reducer, PBMW clay powder, water, characterized in that it contains oxyethylidene diphosphonic acid OEDFK as a viscosity reducer, acrylic polymer Givpan as a fluid loss reducer and additionally a structure formation regulator - sodium chloride NaCl and is a clay suspension mixed first for 40 minutes at 600 rpm, and then 2 more times for 30 minutes at 600 rpm: once after adding Givpan and NaCl, the second time after adding OEDFK, with the following ratio of components, wt.%:

[0011] OEDFK 0,1-0,49 Givpan 0,34-0,81 PBMW clay powder 7-10 NaCl from more than 0 to 0.29 Water Rest

[0012] Givpan is a hydrolyzed polyacrylonitrile, a heat- and salt-resistant acrylic polymer reagent, and a product of the alkaline hydrolysis of polyacrylonitrile. It is a viscous yellow liquid with an ammonia odor and a dry matter content of 18-20%. In experiments conducted with Givpan, the pH of a 10% clay suspension in the presence of Givpan ranged from 11.9 to 12.6, depending on the amount of Givpan added.

[0013] OEDPA - oxyethylidenediphosphonic acid CH3(C(OH)[P(O)(OH)2]2. A strong 5-basic acid. Decomposes at 250°C. Water solubility is 2300 g / l. Forms stable complexes with 2 or more charged cations. OEDPA is a Class 3 hazard reagent. It causes irritation upon contact with skin or mucous membranes. Store the acid in dry, indoor areas, in polyethylene, polypropylene, or multi-layer paper bags. It can be transported by road, water, or rail in waterproof containers or wagons.

[0014] NaCl - or sodium ion, produced according to GOST 4233-77. It is a white crystalline powder. In drilling fluids, it is used to regulate many functions, including the structure-forming properties of clay components. Depending on the ratio of Na ions +to polyacrylate ions (Givpan) point-contact structured systems are formed throughout the entire volume or compact structures of clay particles and loss of kinetic stability of the system.

[0015] The claimed system contains a new combination of reagents that impart a wide range of properties to the solution, which allows us to conclude that the proposed technical solution meets the “novelty” criterion.

[0016] To identify the distinctive properties of reagents and solutions prepared using these reagents, the laboratory conducted comparative tests of the claimed reagent and its prototype. The table provides examples of the preparation of compounds according to the proposed application.

[0017] Example 1. Composition 1. Initial 10% clay suspension of Kurgan clay PBMW, mix for 40 minutes at 600 rpm and measure the parameters of the solution: filtration - F (in cm 3 ), conditional viscosity Tu (in seconds), hydrogen ion pH reducer.

[0018] Example 2. Composition 2. Initial clay suspension of Kurgan clay PBMV, mix for 40 minutes at 600 rpm. Next, add 0.1% OEDFK to this suspension, mix for 30 minutes at 600 rpm, and measure the F, Tu, and pH parameters.

[0019] Example 3. Composition 3. Initial clay suspension of Kurgan clay PBMV, mix for 40 minutes at 600 rpm. Next, add 0.1% FHL to this suspension, mix for 30 minutes at 600 rpm, and measure the F, Tu, and pH parameters.

[0020] Example 4. Composition 4. Initial clay suspension of Kurgan clay PBMV, mix for 40 minutes at 600 rpm. Next, add 0.7% Givpan and 0.29% NaCl to this suspension, mix for 30 minutes at 600 rpm, and measure the F, Tu, and pH parameters.

[0021] Example 5. Composition 5. Initial clay suspension of Kurgan clay PBMV. Mix for 40 minutes at 600 rpm. Add 0.7% Givpan and 0.29% NaCl. Mix for 30 minutes at 600 rpm. Next, add 0.25% OEDFK to this suspension. Mix for 30 minutes at 600 rpm. Measure the F, Tu, and pH parameters.

[0022] Example 6. Composition 6. Initial clay suspension of Kurgan clay PBMV. Mix for 40 minutes at 600 rpm. Add 0.7% Givpan and 0.29% NaCl. Mix for 30 minutes at 600 rpm. Next, add 0.25% FHLS to this suspension. Mix for 30 minutes at 600 rpm. Measure the F, Tu, and pH parameters.

[0023] Example 7. Composition 7. Initial clay suspension of Kurgan clay PBMV, mix for 40 minutes at 600 rpm. Next, add 0.4% Givpan and 0.1% NaCl to this suspension, mix for 30 minutes at 600 rpm, and measure the F, Tu, and pH parameters.

[0024] Example 8. Composition 8. Initial clay suspension of Kurgan clay PBMV. Mix for 40 minutes at 600 rpm. Add 0.4% Givpan and 0.1% NaCl. Mix for 30 minutes at 600 rpm. Next, add 0.49% OEDFK to this suspension. Mix for 30 minutes at 600 rpm. Measure the F, Tu, and pH parameters.

[0025] Example 9. Composition 9. Initial clay suspension of Kurgan clay PBMV. Mix for 40 minutes at 600 rpm. Add 0.4% Givpan and 0.1% NaCl. Mix for 30 minutes at 600 rpm. Next, add 0.5% FHLS to this suspension. Mix for 30 minutes at 600 rpm. Measure the F, Tu, and pH parameters.

[0026] Table

[0027] Examples 10, 11, 12 are prepared similarly to examples 7, 8, 9.

[0028] The results presented in the table are explained by the manifestation of intermolecular forces between the components of the drilling fluid and the clay, each of which is assigned a specific role. Much will be determined by the interaction of clay particles with each other and other reagents. The most important step in preparing the solution is to prevent plane-to-plane interactions of clay particles, when they combine into conglomerates and subsequently precipitate, losing the sedimentation stability of the entire solution. Such a system has a high filtration value of F = 8.8-18.8. That is, it is unstable and requires the addition of a special stabilizing reagent capable of

[0029] a) reduce the filtration index F;

[0030] b) maintain the conditional viscosity T within optimal limits у .

[0031] In the experiments, Givpan was used as a filtration reducer, which at a concentration of 0.4% reduces F from 18.8 (experiment No. 1) to 9.4 cm 3(experiment No. 7). At the same time, the values ​​of T increase у from 24 s to 213.6 s. Apparently, Givpan's macromolecules, containing carboxyl -COOH groups, unhydrolyzed amide -CONH2, and nitrile -CN groups, interact with the active centers (the edges and corners of the clay plates), flocculating and combining them, leading the system to a thick gel-like state. This gelling phenomenon can be prevented by simultaneously introducing a special diluent reagent into the system, which must meet the following requirements:

[0032] 1) reliably block weakly hydrated areas of clay particles - peaks and edges;

[0033] 2) have a high negative charge density and a small molecular weight to successfully displace the functional groups (carboxyl, amide, nitrile) of the Givpan macromolecule formed on the surface;

[0034] 3) a small molecular weight will allow the diluting reagent to have a high diffusion coefficient, which will allow its molecule to quickly block the “dangerous” areas of clay particles from further interaction with the Givpan macromolecule;

[0035] 4) We chose oxyethylidenediphosphonic acid (OEDPA) as the diluent. It is a strong pentabasic acid with a low molecular weight of 206 amu. Therefore, for convenience, its molecule in an alkaline environment can be considered a small particle with a high negative charge density. OEDPA meets all the above conditions. It belongs to hazard class 3 based on its impact on the human body.

[0036] 5) Experiment #5. Comparing the results of Experiments #4 and #5, the effect of introducing OEDFK is clearly visible. Despite the high pH of the suspension (12.07), it was possible to reduce T у304.0 sec. to the optimum - 34.4 sec. The efficiency of OEDFK is also confirmed by the results of experiment No. 8. With an increase in the OEDFK concentration to 0.5% (2 times), the pH value of the suspension drops sharply to 7.85. In this case, the parameters F and T у maintain values ​​acceptable for drilling mud - Ф=6.0 cm 3 and T у =23.2 sec.

[0037] 6) To compare the effectiveness of OEDFK with other liquefying reagents, we selected FHLS. Experiment #3 shows that adding 0.1% FHLS to a clay suspension decreases the pH by 0.18 units (from 10.07 to 9.89). At the same time, adding OEDFK reduces the suspension's pH by 2.0 units. Therefore, FHLS contains weaker acid groups. These are likely carboxyl and phenolic groups of fragments formed during the oxidation of lignosulfonate with potassium bichromate (K2Cr2O7). Similar small pH decreases are also observed when adding FHLS to a clay suspension containing Givpan. A 0.25% concentration of FHLs has virtually no effect on the pH of the medium (from 12.45 to 12.36) (experiments #4 and #6). Adding FHLs to a concentration of 0.5% reduces the pH by 0.45 units (experiments #7 and #9), while OEDFK, under the same conditions, reduces the pH by 4.49 units, or 10 times more.

[0038] 7) Therefore, it can be assumed that after the addition of Givpan and FHLS to the suspension, the larger oxidation products, which have a lower negative charge density and a lower diffusion coefficient, will play a predominant role in the liquefaction process. The results of experiments No. 6 and No. 9 support this assumption. FHLS is a less effective reagent than OEDFK. Apparently, the larger FHLS fragments, which have a lower negative charge density, compete less effectively with the functional groups of Givpan than the five-charged, negatively charged small ions (M = 201 amu) of OEDFK.

[0039] 8) Another advantage of OEDFK over FHLS is its significant environmental friendliness. OEDFK is classified as a Class 3 hazard to humans, while FHLS is classified as a Class 1 hazard because it contains potassium dichromate, which causes chemical burns, has carcinogenic and mutagenic effects, and is particularly hazardous to aquatic organisms and ecosystems. Therefore, the feasibility of using OEDFK in many drilling regions will be determined by its environmental characteristics.

Claims

An environmentally friendly drilling fluid containing a viscosity reducer, a fluid loss reducer, PBMW clay powder, water, characterized in that it contains oxyethylidene diphosphonic acid OEDFK as a viscosity reducer, acrylic polymer Givpan as a fluid loss reducer and additionally a structure formation regulator - sodium chloride NaCl and is a clay suspension mixed first for 40 minutes at 600 rpm, and then 2 more times for 30 minutes at 600 rpm: once after adding Givpan and NaCl, the second time after adding OEDFK, with the following ratio of components, wt.%: OEDFK 0,1-0,49 Givpan 0,34-0,81 PBMW clay powder 7-10 NaCl from more than 0 to 0.29 Water Rest