RU2710654C1 - Highly inhibited invert drilling agent - Google Patents

Abstract

FIELD: soil or rock drilling.

SUBSTANCE: invention relates to drilling of vertical, directional and horizontal wells, in particular, represented by powerful deposits of high-viscosity clays susceptible to swelling and softening, including changes in integrity of the well shaft, especially in its horizontal part. Highly inhibited invert drilling fluid for drilling wells in difficult mining and geological conditions contains, wt%: marble chips 5–10; polyanionic cellulose 5–10; potassium chloride 2–5; potassium methylsiliconate 1–4; potassium acetate 1.5–4; ferrochrome lignosulphonate 1–5; organosilicon liquid GKZh-11 2–5; barite – 0.5–5; antifoaming agent – 0.5–1; potassium aluminate 1–5; surfactant PAV-OP-10 1–2; emulsifier MP 1–5; reagent K–4 1–10; flaking graphite 0.5–5; water – balance.

EFFECT: improved structural-rheological, inhibiting, lubricating, filtration, fixing, anti-gripping and environmental properties of drilling fluid for construction of wells in complex geological conditions.

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Description

The invention relates to the field of drilling vertical, directional-vertical and horizontal oil and gas wells, in particular represented by powerful deposits of highly viscous clays, prone to swelling softening, including with changes in the integrity of the wellbore, especially in its horizontal part, and is also intended for drilling wells in mining rocks where the probability of differential sticking is quite high.

Known drilling mud for drilling wells (see RF patent for the invention No. 2518287, publ. 10/27/2000, IPC S09K 7/07), including the oil product SMAD, carboxymethyl cellulose, potassium chloride and water.

The disadvantages of the above solution include the fact that the solution does not have a sufficient degree of lubrication and inhibition, that is, it is not possible to achieve the formation of a high-quality polymer clay crust on the walls of the wellbore.

Known patent for drilling mud "Drilling fluid to prevent sticking and gland formation BUR - 6". Application for invention RU 94005919 A1, publ. 1997.04.10, consisting of bentonite clay, electrolyte, reagents - viscosity regulators, SNA and water loss, oil-containing additives SKBV, barite, the rest is water.

The disadvantage of this drilling fluid is that, being good as a lubricant, it does not solve the problem of keeping the wellbore upright, especially if the section is represented by viscous, unstable, plastic, clay deposits prone to swelling, as well as the problem of establishing osmotic equilibrium, or creating conditions when the osmosis will be directed from the reservoir into the well.

Known drilling fluid "Highly inhibited drilling fluid", patent RU No. 2303047, C1 publ. 05/10/2006, IPC С09К 8/20, consisting of bentonite clay, polyanionic cellulose, potassium chloride, ferrochrome lignosulfonate, barite, potassium methylsiliconate, potassium acetate, soda ash, bischofite, phosphatide concentrate, nitrilotrimethylphosphonic acid, nitrilotrimethylphosphonic acid.

The disadvantage of this solution is that, working as an inhibitory one, it does not completely solve the problem of keeping viscous, heaving, softening clays in a steady state, especially in deviated and horizontal wells, contributing to the occurrence of differential sticking.

The solution does not solve the problem of establishing osmotic equilibrium, or creating conditions when the osmosis will be directed from the reservoir into the well.

Known drilling fluid, taken as a prototype "Drilling fluid" patent RU No. 2582197 C1 publ. 04/20/2016, bull. 11, IPC 09K 8/10, consisting of marble chips, polyanionic cellulose, sulfanol, potassium chloride, potassium methylsiliconate, potassium acetate, bischofite, ferrochrome lignosulfonate, GKZh-11, barite, antifoam, the liquid phase - the rest, and the liquid phase includes vegetable waste oil and water in the ratio of wt. %: 55 / 45-80 / 20.

The disadvantage of this solution is that it solves the problem of holding in a stable state viscous, heaving, softened clay, especially in deviated and horizontal wells, but it cannot completely solve this problem. As for differential sticking, this solution solves the problem of avoiding them, but when really geological conditions are difficult to meet, an irreversible process occurs - sticking. Thus, the solution does not solve the problem of establishing osmotic equilibrium, or creating conditions when the osmosis will be directed from the reservoir into the well.

The objective of the invention is the development of a multifunctional drilling fluid with the highest inhibitory, filtration, crust-forming, lubricating, anti-seizing properties and providing the establishment of osmotic equilibrium, or creating conditions when the osmosis is directed from the formation into the well. In this case, the water loss should be close to 0 cm ³ in 30 minutes, and the friction coefficient should not exceed 0.1.

The problem is solved due to the fact that the drilling fluid for drilling wells, including polyanionic cellulose, potassium chloride, barite, PAV-OP-10, ferrochrome lignosulfonate, potassium aluminate, MP emulsifier, K-4 reagent, flake graphite, potassium methylsiliconate, potassium acetate , antifoam, water, marble chips, GKZH-11, in the following ratio of components, wt. %: marble chips - 5-10, polyanionic cellulose - 5-10, potassium chloride - 2-5, potassium methylsiliconate - 1-4, potassium acetate - 1.5-4, ferrochrome lignosulfonate - 1-5, GKZh-11 - 2 -5, barite - 0.5-5, antifoam - 0.5-1, potassium aluminate 1-5, PAV-OP-10 1-2, emulsifier MP 1-5, reagent K-4 1-10, flake graphite 0.5-5, water - the rest.

The technical result is an improvement in the fastening, lubricating and anti-seizing properties of a hydrocarbon-based drilling fluid while improving the recovery coefficient of the initial permeability of the reservoir by increasing the inhibitory and hydrophobizing ability of the mud filtrate and, as a result, the absence of gutters and differential sticking in the wellbore, increasing stability trunk of directional and vertical wells.

A multifunctional highly inhibited, invert drilling fluid is proposed for drilling wells in difficult geological conditions (rocks become swell, swell, crumble, differential sticks occur). Areas with such a geological section are found both in the south and in the north of Russia. In the field, when the replacement of the solution is time-consuming, which leads to complications, the use of the proposed solution is an urgent need and it is this composition of the solution that allows successfully, without geological complications and differential sticking, construction of oil and gas wells.

The novelty of the proposed composition of the drilling fluid is that it is in such a percentage and by the name of the chemicals that the proposed solution will solve the problem of wiring oil and gas wells, that is, to fulfill its multifunctionality - to strengthen the walls of the wells, give high rates of filtration and lubricity.

The presence of just this type of two emulsifiers makes the solution invert with a high degree of emulsion, which contributes to a significant reduction in differential sticking.

Without solving these problems, it is almost impossible to complete the construction of oil and gas wells without accidents and complications.

Improving the inhibitory quality of the solution is possible by increasing its fastening effect. In the mechanism of the synergistic effect, a constituent share of the action of each reagent is confirmed and this is achieved through the introduction of clay swelling inhibitor reagents:

1. Potassium chloride (KCl) - the main supplier of the K ⁺ cation, plays a decisive role in the inhibitory effect of the solution. Due to the size of the ionic radius, potassium cations can enter interpackage voids of the crystalline surface of clay minerals, firmly coalescing their packets and promoting interlayer dehydration of clays.

2. Potassium acetate (СН ₃ СООК) - supplements the fixing effect of potassium chloride by influencing the structural - adsorption strains in the clay - liquid system, helping to reduce the swelling fluid content in hydrated clay and stabilize the wellbore.

3. Organosilicon liquid (GKZh-11) - due to the hydrophobizing effect on rocks, it reduces the moisturizing ability of the solution and prevents the rapid development of hydration of water-sensitive clays.

4. Ferrochromlignosulfonate (FHLS) - contributes to the manifestation of a synergistic effect due to the size and structure of the reagent macromolecules adsorbed on clay particles.

5. Potassium methylsiliconate (CH ₃ SiO ₂ K) - due to the presence of K ⁺ ions, complements the fixing effect of the solution, affects the magnitude of structural and adsorption strains in the clay-liquid system, helps to reduce the swelling fluid content in hydrated clay and stabilizes the wellbore.

6. Potassium aluminate (K ₂ Al ₂ O ₄ ⋅ 3Н ₂ О) supplements the fastening action of potassium in solution, reduces the magnitude of structural and adsorption deformations in the clay-liquid system.

The dependences of plastic viscosity, dynamic shear stress and solution filtration on the concentration of inhibitory reagents used in it were revealed: potassium chloride, potassium aluminate, potassium acetate, organosilicon liquid, potassium methylsiliconate, ferrochrome lignosulfonate.

The combination of these six main reagents, inhibitors, is the most beneficial combination found synergistically for drilling wells in difficult conditions.

Surfactant PAV-OP-10 performs the function of an emulsifier and is a synthetic anionic surfactant in the form of a powder, it dissolves well in water, forming an emulsion.

Emulsifier MP is a hydrocarbon solution of esters of fatty acids and triethanolamine.

The combination of these two strongest emulsifiers makes the highly inhibited solution also invert with high lubricity.

Scale graphite, which is a black powder, greasy (slippery) to the touch, which dissolves well in a mixture of two emulsifiers, also gives high lubricating properties to the solution. It is this combination of lubricant (flake graphite) and two emulsifiers (PAV-OP-10 and MP) that made it possible to obtain a lubricant for drilling mud of very high quality. Polyanionic cellulose, PAC 85/700 reagent and K-4 are the strongest filtration reducers, able to reduce fluid loss to almost 0 cm ^3/30 minutes, it was worked into a bundle. Marble chips, in this case, are the best structure formers compared to bentonite clay. Penta 465 is used as a defoamer. Barite is used as a weighting agent (BaSO ₄ ).

The presence of two emulsifiers (PAV-OP-10 and MP) and flake graphite (up to 5%) gives the drilling fluid an emulsion type, that is, water particles are dissolved in the emulsion. This type of solution is called invert, refers to emulsions of the second kind and is reversible.

The rheological behavior of the proposed solution is evaluated and the totality of its mathematical models with improved structural - rheological, filtration and friction properties is established.

Field experience of the implementation of the proposed solution showed that the rheological parameters of the solution contribute to improving the condition of the wellbore and the effective implementation of the hydraulic program of flushing the well.

A complex, multicomponent, high molecular weight inhibitory solution is proposed that has very high lubricating, filtration, and fixing properties with high-quality rheological parameters, with an isotonic coefficient of 5.1.

The proposed drilling fluid is prepared directly in the field using existing equipment. All necessary chemicals are pre-imported to the rig. First, a solution of marble chips and water is prepared in the clay mixer, which is then treated with polyanionic cellulose and K-4 reagent. All other chemicals are introduced gradually into the clay mixer with constant stirring. The order of loading of chemicals is as follows: PAV-OP-10, emulsifier MP, KCl, FHLS, CH ₃ COOK, CH ₃ SiO ₂ K, K ₂ Al ₂ O ₄ ⋅ 3H ₂ O, GKZh-11, Penta 465, BaSO ₄ . The determination of the rheological characteristics of the drilling fluid is carried out according to standard methods. Drilling fluid must be cleaned using a 4-stage cleaning. A high pressure dispersant is used to prepare the solution.

The inhibition mechanism is as follows: when inhibiting additives are introduced into the drilling fluid, physico-chemical interaction of clay and cations occurs, which replace free, negatively charged sections in the crystal lattice of clay particles. With cation exchange, previously passive clay sections are activated. Adsorption of clay cation inhibiting reagents on clay particles increases their resistance to moisture, reduces the swelling and softening of clays.

One of the main conditions for maintaining stability of the borehole walls to provide a minimum possible filter index close to 0 cm ^3/30 min. This condition is met using PAC 85/700 polyanionic cellulose and K-4 reagent.

It has been established that the main role in the intensification of the clay softening process is played not by the initial moisture, but by the saturation of the mud with the filtrate under the action of repression on the formation. Absorption of the mud filtrate occurs not so much under the influence of the pressure drop in the well-reservoir system, but as a result of the physicochemical interaction developing in the clay rock itself. The most optimal, from the point of view of the stability of the walls of the well, are cases when the osmotic equilibrium is established in the well-formation system, or osmosis is directed from the formation into the well.

Despite the fact that in the case of osmosis from the formation into the well, a change in the parameters of the drilling fluid occurs, it is much easier to manage them and maintain them within specified limits than to deal with complications after the destabilization of the wellbore.

Therefore, the stability of clays will depend on the correctly selected composition of chemicals and, first of all, on the inhibitory composition of the reagents. This is the main task that needs to be addressed.

The use of the proposed solution allows you to drill rock intervals, represented by unstable, highly plastic, softened clay and successfully build not only vertical wells, but also directional and horizontal.

The use of reagents with the properties of inhibitors allows for controlled coagulation, to maintain the pH of the medium within the required limits, to regulate structural-rheological, filtration indicators and the optimal level of lyophilism.

Laboratory studies have made it possible to establish that the use of exactly six such clay swelling inhibitors simultaneously in one solution made it possible to achieve a synergistic effect, i.e. enhancing the inhibitory effect of each chemical agent separately, while each reagent, complementing each other, increases the fastening properties of the drilling fluid as a whole. The reagent complex works better than each component individually.

In addition, due to the selection of chemicals in this composition, sodium cations are displaced from clay deposits, sodium clay is converted to calcium, and this also has an inhibitory function, helping to reduce hydration and swelling, reducing bulging, fluidity, collapses and talus of rocks.

The advantage of the solution of the developed formulation is that as a result of its interaction with the studied clays, the concentration of K ⁺ ions increases to 18000 mg / l, which leads to an additional improvement in the quality of the solution and indicates that the osmotic process is directed from the formation into the well. The presence of K ⁺ ions in solution in such an amount contributes to a significant increase in the isotonic coefficient to 5.1. Thus, an increase in the number of osmotic active particles in solution occurs due to dissociation of the electrolyte.

Studies performed in laboratory conditions made it possible to select the optimal composition and parameters of a highly inhibited, invert drilling fluid.

The combination of just such chemicals allowed us to achieve a synergistic effect, that is, the chemicals used are not ontogonists, but complement the useful properties of the solution in terms of inhibitory, filtration and lubricating indicators.

The proposed solution has very high inhibitory properties, zero filtration, has improved structural and rheological, anti-seize and environmental properties for complicated drilling conditions. The phenomenon of a synergistic effect during complex treatment of the drilling fluid with several reagents - inhibitors is experimentally confirmed.

When drilling an exploratory well on the Coastal area of the Krasnodar Territory, the improvement of the fixing properties of the solution due to the synergistic effect of the proposed components has been proved.

The studies performed allowed us to draw the following conclusions:

1. the use of this solution allows you to successfully build exploration wells for oil and gas with a depth of 3000 m with a horizontal end, in areas represented by unstable highly plastic clays and self-dispersing shales;

2. The synergistic effect of the action of the solution components has been experimentally confirmed - the reagent complex works better than each component individually;

3. the proposed composition of the new solution has the highest inhibitory ability, helps to slow down the process of hydration and swelling of clay deposits;

4. the proposed combination of reagents allows the solution to successfully prevent, suspend and suppress deformation processes in the borehole space, reduces cavernousness;

5. It is proved that the proposed solution has improved lubricating and anti-seizing properties with significant energy-saving indicators and a sufficient level of environmental safety of all additives, while differential sticking is practically eliminated, the rheological profile of the washing liquid velocities in the annular space is improved, and the stability of the emulsion is increased. This contributes to the efficient implementation of a hydraulic well flushing program.

In the claimed solution with an optimal ratio of components there is a synergistic increase in the effectiveness of the inhibitory, filtration, lubrication, anti-seizure and anti-wear effects of individual components, while the solution retains its properties at temperatures up to 130 ° C.

Proposed drilling fluid hydrocarbon based high inhibitory, lubricating properties and filtration has parameters: filtering the solution - close to 0 cm ^3/30 minutes, peel tackiness close to 0, the friction coefficient is less than 0.1, the thickness of the cover is less than 0.3 _mm; the density of the solution is from 1.1 to 1.25 g / cm ³ , the conditional viscosity according to SPV-5 is 35-40 seconds, the plastic viscosity is 20-40 mPa⋅S, the SNS 1/10 minutes is 15-20 / 20-30 dPa, sand content less than 0.5%, the content of K ⁺ ions is 18000 mg / l.

Claims (1)

Highly inhibited invert drilling fluid for drilling wells in difficult geological conditions, including marble chips, polyanionic cellulose, potassium chloride, ferrochrome lignosulfonate, potassium methylsiliconate, potassium acetate, GKZh-11 organosilicon fluid, barite, antifoam, which additionally contains water potassium aluminate, surfactant PAV-OP-10, emulsifier MP, reagent K-4, flake graphite, in the following ratio, wt.%: marble chips 5-10; polyanionic cellulose 5-10; potassium chloride 2-5; potassium methylsiliconate 1-4; potassium acetate 1.5-4; ferrochrome lignosulfonate 1-5; GKZH-11 2-5; barite 0.5-5; defoamer 0.5-1; potassium aluminate 1-5; PAV-OP-10 1-2; emulsifier MP 1-5; reagent K-4 1-10; flake graphite 0.5-5; water the rest.