RU2516400C1 - Alum-gypsum-potassium drill mud and method of its production - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: water-based drilling mud is suggested with the following composition, in kg/m³: aggregating agent Base Medium B 10-40; KOH 0.05-0.3; rheology regulator component Poliksan 1.5-4.0; mud filtration regulator component Osnopak NO 0.8-3.0; rheology and filtration regulator component Osnopak VO 0.5-1.0; filtration regulator component Amilor R-122 12-30; pH regulator, swelling inhibitor - hydrated lime 2-5; swelling inhibitor - gypsum 15-18; potassium alum AlgypoDS-103 1,0-3,0; colmatant-filler UMS-100 40-200; process water - remaining volume up to 1 cubic metre, and the method for drill mud production.

EFFECT: ensuring high inhibiting and low dispersing properties of the drill mud, low water loss preventing slides and collapses, reducing moisturising properties of the mud.

2 cl, 2 tbl

Description

The invention relates to the field of petrochemistry, the production of inhibited systems of drilling fluids used in the drilling of oil and gas wells, namely, inhibitory alumina-gypsum potassium drilling fluid and the method for its production.

In drilling practice, drilling fluids are used in aqueous (industrial water, salt and hydrogel solutions, polymer, polymer-clay and clay solutions), hydrocarbon (lime-bitumen, invert emulsion) and aerated substrates, (see Wikipedia - Internet encyclopedia

http://m.wikipedia.org/wiki/%C1%F3%F0%EE%E2%EE%E9%F0%E0%F1% F2% E2% EE% F0, 01/10/2012).

When drilling in chemogenic deposits, saline clay solutions, hydrogels are used, in case of possible shedding and landslides of the well walls, inhibited solutions are used, when exposed to high temperatures, heat-resistant clay solutions and hydrocarbon-based solutions are also effective when opening productive formations and when drilling terrigenous and chemogenic unstable rocks.

When drilling under conditions characterized by abnormally high pressures, weighted drilling fluids are used, in uncomplicated conditions - industrial water, polymer clay-free and polymer-clay solutions with a low solids content (see http://www.mramor-m.ru/informatsionnie -stati / burovie-rastvori-klassifikatsiya).

Process water is the most affordable and cheapest flushing fluid. Having a low viscosity, it is easily pumped, well removes sludge from the bottom of the well and cools the bit better than other fluids.

However, it poorly retains particles of drill cuttings (especially when the circulation ceases), does not form a strengthening crust on the well wall, is well absorbed by low-pressure formations, causes swelling of clay rocks, and worsens the permeability of oil and gas reservoirs.

A natural drilling fluid is an aqueous suspension formed in a well as a result of dispersion of rock sludge drilled on water. The main advantage of using natural drilling fluids is a significant reduction in the need for imported materials for their preparation and processing, which leads to cheaper solutions. However, their quality and properties depend on the mineralogical composition and nature of the drilled clays, the method and mode of drilling, such as a rock cutting tool. Often they contain a high content of abrasive particles. Therefore, natural drilling fluids are used in cases where, according to geological and stratigraphic conditions, high quality is not required.

Clay drilling fluids are most common when drilling wells. For drilling, three groups of clay minerals are of most interest: bentonite (montmorillonite, beidellite, nontroiite, saponite, etc.), kaolin (kaolinite, halloysite, nakrit, etc.) and hydromica (illite, braviazite, etc.). Montmorillonite and other bentonite minerals have the best quality in terms of drilling fluid preparation. Clay solutions clay the well walls, forming a thin dense crust, which prevents the filtrate from penetrating into the reservoirs. Their density and viscosity are such that the solutions keep the cuttings of the drilled rock even at rest, preventing it from settling on the face during breaks in flushing. Weighted clay solutions, creating a large back pressure on the reservoirs, prevent the penetration of formation water, oil and gas into the well and open gushing during drilling. However, for the same reasons, it is difficult to separate the rock particles in the circulation system of the drilling fluid.

Other water-based drilling fluids are also used: low-clay (for drilling the upper stratum of weathered and fractured rocks), salt-saturated (when drilling in thick strata of saline rocks), inhibited (treated with chemicals to prevent swelling of the drilled rocks and excessive enrichment of the solution with a solid phase) and etc.

Non-clay drilling fluids are prepared without the use of clay. A clay-free mud with a condensed solid phase is prepared on a water basis. The dispersed phase in it is obtained chemically, as a result of the interaction of magnesium ions in solution with alkali NaOH or Ca (OH) ₂ . The chemical reaction leads to the formation of microscopic particles of magnesium hydroxide Mg (OH) ₂ in the solution. The solution acquires a gel-like consistency and, after chemical treatment, turns into a sedimentation-stable system. Such a solution retains its structural and mechanical properties during any mineralization. Therefore, it is used in cases where it is required to ensure high stability of the walls of the well, but it is difficult to control and regulate the mineralization of the solution.

Known application for opening productive formations and drilling appraisal wells oil-based solutions (RNO) and lime-bitumen solutions (IDB). RNO and IDB contain diesel fuel, highly oxidized bitumen, synthetic fatty acid (FFA), caustic soda (NaOH), surfactants such as sulfonol, SMAD, etc. Their difference is that the CBR contains active lime [Ryazanov A .I AM. Reference for drilling fluids. - M .: Nedra, 1979, p. 54].

The disadvantage of these solutions is the high time required for operations associated with heating and dissolving bitumen in diesel fuel. As practice shows, it takes 10-12 days to prepare a hydrocarbon-based solution (CBR) using highly oxidized bitumen in a volume of 150 m ³ in wells. Of this time, about 80% is spent on dissolving bitumen.

Known solution [A.S. USSR 1516486 A1, C09K 7/06, 1989], including oil or diesel fuel, organophilic bentonite based on alkylbenzyldimethylammonium chloride, tire regeneration obtained by the thermal method for the restoration of car tires, barite. The ingredients are taken in the following ratio, wt.%:

Oil or diesel fuel - 54.0-56.0

Organophilic Bentonite Based

alkylbenzyldimethylammonium chloride - 6.5-7.0

Tire regenerate obtained by the thermal method for the restoration of car tires - 3.0-5.0

Barite BaSO ₄ - the rest.

This solution has the following disadvantages:

- dissolution of tire regenerate in diesel fuel is a laborious and technologically complex process, since the dissolution operation with simultaneous stirring should be carried out at a temperature of 250 ° C? and to carry out these operations in fishing conditions is very difficult;

- organophilic clay is a very expensive reagent.

A hydrocarbon-based drilling fluid is described [A.S. USSR 1263705, C09K 7/06, 1986], containing, wt.%:

diesel fuel 34-75,

synthetic fatty acids FFA 0.5-3.0,

clay powder 1-10,

polyorganoalkoxysilanes and siloxanes 3-8,

caustic soda 0.1-0.2,

weighting agent - barite rest.

A composite reagent for drilling fluids [RU 2186083 C2, 07.27.2002] is described, which has multifunctional properties: heat resistance, resistance to polyvalent cations of filtration reducer, while at the same time improving its lubricating and anti-wear properties. Composite reagent for drilling fluids includes GKZh-10 sodium ethylsiliconate, additionally contains carboxymethyloxyethyl cellulose (CMOEC) in the following ratio of components, wt.%: CMOEC 50-65; GKZH-10 30-50.

In [RU 2424269, 07/20/2011], a hydrocarbon-based emulsion solution is proposed, which ensures a decrease in the dispersibility of drilled clay sludge and an improvement in the filtration-capacitive characteristics of the reservoir during the initial opening and killing of wells. The hydrocarbon-based emulsion solution contains, wt.%:

diesel fuel 14.98-84.55,

organophilic bentonite 0.39 ÷ 4.26,

"Emulsifier MP" 0.83-2.38,

"Water repellent ADB" 0,015-0,73,

mineralized with potassium chloride, or sodium, or calcium aqueous phase 1.5-36.73,

20% solution of polyisobutylene with a molecular weight of 20,000 in industrial oil I-20A 0.33-3.81,

calcium oxide 0.39-2.38,

mineral filler - chalk or barite else.

Describes drilling fluid for opening productive formations [RU 2233860 C2, 08/10/2004], containing acrylic polymer, colloidal structurant, colmatant and water, contains rubber crumb modified with oil or its derivatives as colmatant when containing: rubber crumb 27%, oil or its derivatives 73%, in the following ratio of components, wt.%:

acrylic polymer 0.6;

colloidal structurant 3;

the specified rubber crumb 1;

water is the rest.

Known water-based drilling fluid [RU 2009147001 A, 06.27.2011] containing water, bentonite and an additive, which use wastes from the production of detergents as a highly effective surfactant in the following mass ratio of components, wt.%:

Bentonite 5-15

Stabilizer 0.5-1.5

Highly effective surfactant 0,1-0,5

Water Else

The proposed drilling fluid provides high-quality opening of the reservoir and the preservation of its natural permeability.

To prevent accidents and complications associated with talus and collapses of unstable clays, heterogeneous inhibitory drilling fluids are used. The main types of inhibitory drilling fluids are calcareous, gypsum-lime, potassium chloride, gypsum-potassium, calcium-chloride, slightly silicate, and potassium-alumina (see tsogu.ru> media / files / 2009 / 12_02 ... 2008-10-15.doc).

Aluminate fluids are clay clay drilling fluids made of calcium clay that contain an inhibitory additive, a highly alkaline sodium aluminate stabilized by lignosulfonates. Aluminate solutions are fresh and saturated. Fresh aluminate solutions are used to drill clay deposits at low bottomhole temperatures. As a stabilizer reserve, only sulphite-distillery stillage (hereinafter referred to as CSP), used in conjunction with sodium aluminate, is used. Aluminate clay solutions (hereinafter referred to as AlGR) are stable in a wide range of sodium chloride mineralization and low filtration rates.

To prepare an aluminate clay solution, Cherkasy unmodified bentonite or other calcium clay is used. The advantage of AlGR prepared from calcium clays as compared to a solution from sodium clays is the following: with an equal consumption of reagents, it has lower values of the filtration index, viscosity and static shear stress (hereinafter referred to as SNA).

The procedure for preparing AlGR is as follows: clay is added to water containing the required amount of CSP, then sodium aluminate is added; due to insufficient production of sodium aluminate, it is possible to replace it with calcium aluminate, which is used as an alumina or gypsum-alumina cement.

Lime mortars are complex multicomponent systems that include, in addition to clay and water, four essential reagents: lime, caustic, viscosity reducer, protective colloid. They may also include oil or diesel fuel, a weighting agent and various special-purpose additives.

Lime mortars are used for drilling high-colloidal clay rocks and mudstones. As a result of the use of lime solutions, their clay intensity increases, peptization of drilled clay, swelling, swelling of shales forming the well walls decrease, and the risk of sticking decreases.

Unlike aluminate, calcareous solutions are limitedly salt tolerant (up to 5% in NaCl).

The main disadvantage of lime solutions is their low heat resistance (100-120 ° C).

Clay-free salt-resistant solutions (hereinafter BSK) consist of brown coal, caustic soda, water, polyvalent metal hydroxide;

they are used when drilling wells complicated by the presence of chemogenic deposits, crumbling and prone to collapse of terrigenous rocks.

The fastening effect is based on the formation under certain temperature conditions of water-insoluble cementitious substances - hydrosilicates and hydroaluminates of divalent metals. In the absence of divalent cations in the drilling fluid and the rocks being drilled, only chemical destruction by alkali of clay minerals occurs without binding of the destruction products into insoluble compounds. In the absence of caustic soda and the presence of only calcium ions, the drilling fluid turns into a kind of calcium solution.

The fixing effect of the BSK solution is better manifested with a sufficiently high concentration of caustic soda (at least 0.2%) and an excess of undissolved divalent metal hydroxide in the liquid - Ca (OH) ₂ , Ba (OH) ₃ , etc.

The disadvantages of these solutions are low heat resistance and high alkalinity. Since the use of this solution does not exclude the passage of cuttings into it, strong thickening and even hardening of the solution is possible.

Calcium solutions - inhibiting clay wash solutions containing, in addition to clay, water, oil and weighting agent, viscosity reducing agents, filtration and alkalinity regulators, special substances - carriers of calcium ions.

Their action is mainly to prevent the transition of drilled clay to sodium form, to convert sodium clay to calcium, resulting in reduced hydration and swelling of shale.

Gypsum-lime solution - an inhibiting calcium solution containing gypsum and calcium hydroxide as a carrier of calcium ions.

The addition of gypsum (alabaster) to the solution is 20-25 kg / m ³ . The content of soluble calcium depends on the quality of the gypsum, the lignosulfonates used, the pH of the drilling fluid and can be in the range of 70-3000 mg / l.

Gypsum solutions are designed for drilling high-colloidal clay rocks at high bottomhole temperatures (up to 160 ° C).

Calcium chloride solution (hereinafter CLC) is an inhibitory calcium solution containing calcium chloride as an inhibitory additive.

It was found that the optimal content of calcium cations, at which inhibition is achieved, is 3000-5000 mg / l. Calcium chloride solutions are most effective in drilling mudstones. The presence of calcium ions in the filtrate of the drilling fluid contributes to a significant reduction in scree and landslides during drilling of unstable argillite-like deposits.

Due to the lack of effective calcium-resistant reagents, its heat resistance is limited (100 ° C).

Potassium drilling fluids contain potassium compounds as inhibitory electrolytes. The action of potassium solutions is due to the saturation of clay minerals with potassium ions. The fastest saturation of clays with potassium ions occurs at pH 9-10.

Potassium solutions are effective in drilling unstable clay-argillite deposits and shales. There are a number of varieties of potassium fluids, differing in composition and some properties: potassium chloride fluids, potassium-gypsum fluids, potassium clay mud, inhibiting potassium mud based on lignosulfonates, highly inhibiting humate based potassium mud (VICR), inhibiting potassium drilling mud ICSI, highly inhibiting mud IKGLIK solution.

Among the inhibitory drilling fluids, a special place is occupied by fluids treated with salts of trivalent metals; one of the most effective among them is potassium alumina. As an inhibitory additive, it contains potassium alum, potassium hydroxide and sodium dichromate; The pH of such solutions is maintained close to neutral. The inhibitory effect of this solution is higher; it can also be used to drill moist clay deposits (tsogu.ru> media / files / 2009 / 12_02 ... 2008-10.15.doc).

The closest in composition to the claimed is a drilling fluid using as an inhibitory additive potassium alum

(see. http: //www.mirrico.ru/press/articles/index.php? ELEMENT ID = 1470).

The aluminum hydroxide formed in the solution, adsorbed on the cuttings, prevents its passage into the drilling fluid. Getting into cracks and pores, aluminum hydroxide clogs them, reducing formation watering and strengthening the well walls. In addition, the inhibitory effect is achieved due to the blocking of the hexagonal structure of clay minerals by potassium cations and a decrease in their hydration. As carriers of calcium cations, gypsum and calcium hydroxide (slaked lime) were used. The addition of gypsum is 20-25 kg / m ³ . The content of calcium cations depends on the quality of gypsum, the pH of the drilling fluid and is 700-3000 mg / l. In this case, calcium cations reduce the hydration of clay minerals, and lime, adsorbed on particles of drill cuttings, reduces their activity. To maintain the pH of the solution at the level of 8.5-9.5, KOH and lime are added.

All the above drilling fluids, as well as the prototype, except for the noted drawbacks, are not effective enough when drilling such types of rocks as sandstones, dolomites with interlayers of clays, mudstones, marls, siltstones, characterized by instability due to absorption of drilling fluids by the rocks, swelling of clays and the occurrence of scree landslides, accompanied by sticking of the drilling tool.

The objective of the invention is the creation of a new drilling fluid, contributing to the construction of a wellbore on unstable soils, composed of clay-argillite deposits, sandstones and carbonate rocks with inclusions of gypsum and anhydrite, without complications in the form of scree and landslides and accidents, which will lead to a significant reduction in material costs during the construction of the wellbore.

The technical result of the invention is to provide high inhibitory and low dispersing properties of the proposed drilling fluid, low water loss, preventing scree and landslides, reducing the wetting ability of the solution.

The problem is solved by the composition of the drilling fluid, in which, as in the prototype, aluminum potassium alum, as well as gypsum and calcium hydroxide (slaked lime), which is also used as a pH regulator together with potassium hydroxide, are taken as an inhibitory additive. The difference from the prototype is the following. AlgypoDS-103 was taken as alum-potassium alum, a structure-forming agent, a rheology regulator, a filtration regulator, and a weighting compound were additionally introduced. The base Medium B component was taken as a builder, as a regulator of rheology, Poliksan, Osnopak VO, working together with each other, as a filter regulator Osnopak NO, Amilor 122 and Osnopak VO, as a weighting agent-weighting agent - UMS-100 (CaCO ₃ ) , which at the same time increases the density of the drilling fluid and performs the function of colmatant. The pH of the solution is 9.0-10.5, the density is 1060-1250 kg / m ³ , the nominal viscosity is 35-75 seconds, while the total qualitative and quantitative composition of the drilling fluid is represented by the following components, in kg per cubic meter:

Structuring agent Basis Medium B 10-40 CON 0.05-0.3 Polyoxan rheology regulator 1.5-4.0 Osnopak BUT solution filtration regulator 0.8-3.0 Regulator of rheology and filtration Osnopak VO 0.5-1.0 Filtration regulator Amilor R-122 12-30 PH Regulator, Lime Swelling Inhibitor 2-5 slaked Gypsum Swelling Inhibitor 15-18 Potassium Alum AlgypoDS-103 1.0-3.0 Kolmatant weighting compound UMS-100 (CaCO ₃ ) 40,0-200 Process water The rest is up to the cube

Additionally, other components can be added to the drilling fluid as a bactericidal additive, a lubricant, a hydrogen sulfide scavenger, dispersing agent, antifoam, etc.

The problem is also solved by the method of obtaining the inventive drilling fluid, including preliminary complete dissolution by mixing in industrial water and subsequent introduction into water in the order indicated (following) the following components:

Structuring agent Basis Medium B 10-40 kg / m ³ ;

The rheology regulator Poliksan 1,5-4,0 kg / m ³ with an input intensity of 25 kg for 5-10 minutes;

Osnopak VO 0.5-1.0 kg / m ³ with an input intensity of 25 kg in 5-10 minutes;

Osnopak BUT 0,8-3,0 kg / m ³ with an input intensity of 25 kg for 5-10 minutes;

Amilor R-122 12-30 kg / m ³ with an input intensity of 25 kg in 5-10 minutes;

Lime diluted with a small amount of water (in the form of "milk of lime"), in an amount of 2-5 kg / m ³ (to maintain the pH of the solution in the range of 9-10.5);

Gypsum, diluted with a small amount of water, in the amount of 15-18 kg / m ³ , bringing the pH of the drilling fluid to 9-10.5;

AlgypoDS-103 potassium alum, in an amount of 1-3 kg / m ³ , with control of the pH of the drilling fluid and bringing it to a value of 9-10.5, after their introduction, the pH of the total solution is adjusted to 9-10.5 by adding slaked lime within specified amount;

Colmatant UMS in an amount sufficient to bring the density of the drilling fluid to a value of 1060-1250 kg / m ³ .

Similar builders of this kind are also found in other drilling fluids, from other manufacturers, but their use will lead to the fact that the properties of the solution can change, which in turn will cause a change in the dosages of both the additive itself and other components of the solution. The basis of Medium B in the specified amount will allow to provide, together with other components, the required properties of the resulting solution.

It is known to use the components responsible for the rheological properties of the solution, however, the joint use as regulators of the rheology of Polyksan, Osnopak VO guarantees the final result. Separately, the desired rheological properties cannot be obtained.

Filtration regulators Amilor R-122, Osnopak BUT, Osnopak VO together give a good result. At the same time, Osnopak VO is both a structure-forming agent and a filtering regulator.

In the process of obtaining a drilling fluid of the specified composition, the following components were used:

Component Name Name of technical documentation Manufacturer Chemical formula function Potassium Alum AlgypoDS-103 TU 2458-031-63121839-2011 000 "Industrial chemistry" complex composition Clay Swelling Inhibitor Amilor R-122 TU 2458-002-82330939-2009 000 "Mirrico comprehensive support" Modified Starch Mud filtration regulator Plaster AlgypoDS-2 GOST 125-79 000 "Arakchinsky gypsum" Calcium sulphate Clay Swelling Inhibitor Slaked lime AlgypoDS-1 GOST 9262-77 OJSC "Building Materials" Calcium hydroxide Clay pH Inhibitor of Clay Swelling Basis Medium B TU 2458-016-82330939-2009 000 "Mirrico comprehensive support" complex composition Structural educator Osnopak VO TU 2231-011-63121839-2010 000 "Industrial chemistry" Carboxymethyl cellulose Rheology and Filtration Regulator Osnopak BUT TU 2231-011-63121839-2010 000 "Industrial chemistry" Carboxymethyl cellulose Mud filtration regulator Polyksan TU 2458-017-82330939-2009 000 "Mirrico comprehensive support" Polysaccharide B Rheology regulator UMS TU 2458-012-82330939-2009 000 "Mirrico comprehensive support" Calcium carbonate Colmatant weighting compound

Technical water used during drilling had the following characteristics:

Parameter Content

Total hardness, mg / l, no more 200 Salinity, mg / L 500 pH 6-8

When using such a composition of the solution obtained in this way, the following processes occur:

1) aluminum hydroxide is formed in the solution, which, being adsorbed on the cuttings, prevents its passage into the drilling fluid. Getting into the cracks and pores, aluminum hydroxide clogs them, reducing watering in the reservoirs and strengthening the walls of the well; the use of potassium alum is known; potassium cations block the hexagonal structure of clay minerals and reduce its hydration; blocking of the structure of clay materials by potassium cations is known

2) lime is adsorbed on drill cuttings, reducing their activity and increasing the clay content of the solution.

Thus, the walls of the well are strengthened, reducing their collapses and destruction, which indicates the effectiveness of the drilling fluid. The selected balance of reagents allows maintaining the calcium and alkalinity at a certain level, and complex hydroxosulfoaluminates are formed in the solution, which precisely determine the strengthening properties of the drilling fluid with respect to the walls of the well.

In the case of using gypsum types of solutions in the presence of dissolved anhydrite, the magnesium component of dolomite is “washed out” with its subsequent destruction, which can cause cavern formation and instability of the borehole walls. When using the inventive solution, such negative processes can be avoided due to the presence of aluminum cations, more precisely, aluminates, both in dissolved and in bound form in the form of calcium aluminate. The presence of aluminum allows the formation of calcium / magnesium hydrosulfoaluminates and calcium / magnesium hydrocarboaluminates in the walls of the well, which form a spatial structure inside the anhydrite / dolomite, while binding a large amount of water. Such processes from the prior art are unknown and lead to hardening of the borehole wall, as well as to a decrease in its permeability. In addition, the composition of the drilling fluid in connection with the requirements of customers is very complex, and it was difficult to achieve a balance of qualitative and quantitative composition in order to provide the required properties of the fluid and satisfy conflicting customer requirements. This balance in the inventive solution is provided both by the composition itself and by the method of its preparation, prescribing a certain sequence of the above operations.

The technology of preparing the inventive drilling fluid is as follows.

To prepare the drilling fluid, take a block with a volume of 12-15 m ³ , equipped with a stirrer, a vacuum hydraulic funnel operating from a centrifugal pump, and a dosing tank with a volume of 0.7 -1.0 m ³ intended for the preparation of concentrated liquid solutions from dry chemical reagents for their adding to the drilling fluid.

Fresh technical water is collected in the drilling fluid preparation unit. The component Basis Medium B is introduced at a rate of 10-40 kg / m ³ , mixed for 60-120 minutes to more fully disperse the clay. Then, the following components are sequentially introduced into the prepared solution through a hydraulic funnel in the following order with the input intensity of each polymer component 25 kg in 5-10 minutes to prevent the presence of inclusions in the form of folded unbroken lumps of polymers:

Polyksan at the rate of 1.5-4.0 kg / m ³ ; Polyksan input is controlled by the conditional viscosity and dynamic shear stress (hereinafter CSN) of the prepared solution;

Osnopak VO at the rate of 0.5-1.0 kg / m ³ ;

Osnopak BUT at the rate of 0.8-3.0 kg / m ³ ;

Amilor at the rate of 12-30 kg / m ³ ,

in order to improve dispersion, each polymer is recommended to be pre-mixed with neutral technical water prepared for the preparation of drilling mud with an initial pH value of 6.5-7.0 in a separate container.

Next, lime is first introduced into the prepared solution in a minimum amount of 2 kg / m ³ in the form of “milk of lime”, for which the reagent is diluted with a small amount of water, the solution is stirred for 20-30 minutes until the component is completely dissolved.

Gypsum is introduced into the prepared solution from the calculation (15-18 kg / m ³ ), in the form of an aqueous highly concentrated solution, for which the reagent is diluted with a small amount of water, the solution is stirred for 30 minutes until complete dissolution. The introduction of gypsum into the solution can lead to a decrease in pH, therefore, measure the pH of the solution and, if necessary, adjust its value to 9-10.5 by adding slaked lime.

Next, potassium alum in the amount of 1-3 kg / m ³ is introduced into the prepared solution, after which the pH of the solution is again measured, which may decrease; if necessary, the pH is adjusted by additional input of lime to a value of 9-10.5, the solution is stirred for 30 minutes until the alum is completely dissolved.

Colmatant UMS-100 is introduced into the solution, adjusting the density of the solution to a value of 1060-1300 kg / m ³ , mix the solution for 10-15 minutes to evenly distribute the weighting agent over the volume.

After that, the parameters of the obtained drilling fluid are measured and, if necessary, the fluid is further treated with the appropriate reagents in the above order to control the rheological parameters, filtration properties, etc.

Rheological parameters are regulated by the introduction of polymers Polyksan and Osnopak VO.

The median particle size (parameter d50) of the drilling fluid should be within 33 ÷ 100% of the actual or estimated pore hole size. This 3: 1 range, called the “colmatation ratio,” is the most efficient mixture of CaCO ₃ particle sizes for the rapid colmatation of reservoir sandstones.

The rheological, filtration and inhibitory properties of the solution are evaluated according to standard methods.

The parameters of the solution were measured according to the book of Ryazanov Ya.A., generally accepted by drilling companies. "Encyclopedia of drilling fluids." Density was determined by a lever balance - densitometer, VBR-1 - conditional viscosity, plastic viscosity, CSN and SNA - on a Farm or OFITE viscometer, static shear stress (SNA) - on a SNA-2 device, filtration - according to VM-6 or filter the press.

Table 1 shows the specific compositions of examples of the implementation of drilling fluids. Table 2 shows the parameters of drilling fluids in accordance with examples of compositions from Table 1.

Thus, as shown by the embodiments of the invention, the claimed composition of aluminum-gypsum potassium drilling mud AlgypoDS, obtained in accordance with the claimed method, is optimal for drilling the following types of rocks:

sandstones, limestones, dolomites with interlayers of clays, mudstones, marls, siltstones, characterized by instability due to swelling of clays and screes of mudstones and siltstones; their drilling is accompanied by scree, landslides and absorption of solutions, sticking of the drilling tool;

clay, since drilling clay is associated with great difficulties, due to their easy transition into solution, increasing the content of the solid phase in it; the colloidal component of drilled clays has the greatest influence - drilling fluids should have inhibitory and non-dispersive properties, as well as low water loss;

mudstones, siltstones, clay limestones - these rocks having a lamellar structure are characterized by instability, a tendency to talus and landslides; drilling fluids used in their drilling should have inhibitory and non-dispersive properties. The fluid loss of the solutions should be minimal, since screes along the bedding boundaries are possible.

Table 1 Drilling fluid composition Solution composition Content, kg / m ³ Prototype Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Basis Medium B - 10.0 20,0 20,0 30,0 20,0 40,0 CON 0,03 0.05 0.2 0.25 0.3 0.25 0.3 Polyksan - 2.0 2,5 2,5 1,5 2,5 4.0 Osnopak BUT - 0.8 1,0 1,0 2.0 1,0 3.0 Osnopak VO - 0.5 1,0 1,0 0.5 1,0 1,0 Amilor R-122 - 12.0 15.0 15.0 15.0 15.0 30,0 Alum Potassium Alum 1,0 -AlgypoDS-103 - 1,0 1,5 3.0 2.0 3.0 3.0 Slaked lime 0.7-3 kg / m ³ 2.0 2.0 2.0 3.0 2.0 5,0 Gypsum 20-25 18.0 15.0 15.0 15.0 15.0 15.0 UMS-100 - 40,0 140 60 150 70 200 Those. water The rest is up to the cube The rest is up to the cube The rest is up to the cube The rest is up to the cube The rest is up to the cube The rest is up to the cube The rest is up to the cube

table 2 Drilling fluid parameters Name of parameters Parameter Values Prototype Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Type of solution Based on potassium alum Algypo Algypo Algypo Algypo Algypo Algypo Density, kg / m ³ 1050 1060 1110 1060 1140 1070 1250 Conditional viscosity, s 34 35 43 69 61 51 75 PV, MPa · s 14.5 15.0 16.1 16.9 22.4 18.2 25.0 DNS, dPa 70,4 75.0 96.5 160.8 106,2 112.9 182.5 SNA 10 s, dPa 18.0 20.5 30.1 46.6 29.1 29.6 47.4 SNA 10 min, dpa 20.3 22.5 39.2 60.9 39.3 57.2 104.6 Filtration, ANI / VM-6 7.5 / 6.5 7.5 / 6 6/5 5.5 / 5 7/5 6.4 / 5 5 / 4,5 Ca ++, mg / l 1100 1230 1240 1350 1280 1240 1440 pH 8.5-9.5 9.0 10.5 9.0 10.0 9.5 10.5 Crust, mm 1,5 1,5 1,5 1,5 1,5 1,5 1,5 Sand,% vol. 1,0 1,0 1,0 1.0 1,0 1,0 1,0 Note. PV - plastic viscosity CSN - dynamic shear stress SNA - static shear stress ANI - the value of filtration at the American Petroleum Institute, measured by the filter press VM-6 - filtering value for the VM-6 device.

Claims (2)

1. A water-based drilling fluid of the following composition, kg / m ³ :
Structuring agent Basis Medium B 10-40 CON 0.05-0.3 Polyoxan rheology regulator 1.5-4.0 Osnopak BUT solution filtration regulator 0.8-3.0 Regulator of rheology and filtration Osnopak VO 0.5-1.0 Filtration regulator Amilor R-122 12-30
PH Regulator, Lime Swelling Inhibitor
slaked 2-5 Gypsum Swelling Inhibitor 15-18 Potassium Alum AlgypoDS-103 1.0-3.0 Kolmatant weighting compound UMS-100 40-200 Process water The rest is up to the cube 2. A method of obtaining a drilling fluid, including preliminary complete dissolution of dry components by mixing in industrial water and subsequent introduction into industrial water in the order indicated (following) the following components in quantities in kg / m ³ :
Structuring agent Basis Medium B 10-40 Polyoxan rheology regulator 1.5-4.0 Osnopak VO solution filtration regulator 0.5-1.0 Regulator of rheology and filtration Osnopak BUT 0.8-3.0 Filtration regulator Amilor R-122 12-30
PH Regulator, Lime Swelling Inhibitor
slaked 2-5 Gypsum Swelling Inhibitor 15-18 Potassium Alum AlgypoDS-103 1-3 Kolmatant weighting compound 40-200,
moreover, KOH alkali is introduced into the composition at different stages of the method after measuring the pH of the solution to maintain its pH at the level of 9.5-10.5 in the amount of 0.05-0.3 kg / m ³ , if necessary, slaked lime is additionally introduced after gypsum for pH adjustment at the level of 9.5-10.5, polymer components Poliksan, Osnopak VO, Osnopak BUT, Amilor R-122 are introduced into the prepared solution with a feed rate of 25 kg in 5-10 minutes, and the total amount of process water for the specified number of components take to the cube.