RU2379474C2 - Wells high intensity absorption intervals insulation method and aerated slurry for its execution - Google Patents

Abstract

FIELD: oil-and-gas production.

SUBSTANCE: in a wells high intensity absorption intervals insulation method execute cement slurry pumping, then - a polymer content, at that use an aerated solution as the slurry, with the base, mass p. Portland cement 85-100,alluminium silicate micro spheres up to 15, foam creator - anion SAS base on a resin and naphthene acid basis 0.1-0.3, setting time activator 4.0-7.0, water 50-60, and additionally - gas agent in quantity, providing the mentioned above solution density 800-1000 kg/m³, and a poly-cement paste used as the polymer solution, created by mixing compositions I and II of a defined content. Invention develops in formula subclaime.

EFFECT: insulation works time consumption decrease, creating a reliable insulation in a catastrophic absorption conditions.

6 cl, 1 ex, 2 tbl, 1 dwg

Description

The invention relates to the oil and gas industry and can be used to isolate high-intensity (catastrophic) absorption zones in wells at normal and elevated temperatures.

A known method of conducting insulating work at normal temperatures by injection into the absorption zone of polymer cement paste prepared by mixing two cement suspensions, in the following general ratio of components, parts by weight: cement Portland cement 100; PAA 0.14-0.20; calcium chloride 3.5-5.0; water 55-60 (Bulatov A.I. and Daniushevsky B.C. Grouting materials. M: Nedra, 1987, p.242).

The technological properties of the well-known polymer-cement paste prepared in the laboratory on the basis of these reagents meet the requirements, and the paste can be used to implement the known method under normal temperature conditions with catastrophic absorption. However, the preparation of this paste in drilling conditions causes difficulties, because mixing, pumping and mixing of two cement suspensions to obtain certain structural and mechanical properties is complicated by the non-pumpability of one of these suspensions. In addition, for use at elevated temperatures, it is necessary to adjust the preparation method and properties of the paste used.

Also known is a method of isolating water inflow zones in a well (RF Patent No. 2237797, ЕВВ 33/138, publ. 2004), according to which the polymer composition and cement slurry are sequentially injected into the water inflow zone. In this case, the polymer composition has a curing time of 90-120 minutes, and the cement slurry is injected after the injection of the separating fluid, which simultaneously exhibits the properties of the hardener of the polymer composition and the accelerator of the setting time of the cement slurry, and before and after the separating fluid, fresh water pillows are additionally injected. The specified method allows to increase the stability of the insulating barrier.

However, the use of this known method for the isolation of high-intensity (catastrophic) absorption is inefficient, because when opening the complicated zone, there is a constant flow of formation fluid, and even shortened setting times of insulating polymer and cement compositions cannot guarantee their indelibility.

Closest to the proposed solution is a method of isolation of absorbing formations (RF Patent No. 2112133, ЕВВ 33/138, publ. 1998), by which batch delivery of cement (cement) mortar to the absorption zone is carried out. These portions alternate with portions of a viscoelastic separator - polymer composition, while ensuring pressure balance in the well and reservoir.

The disadvantage of this method is that in the process of stopping the injection (holding the viscoelastic separator to yield fluidity), the polymer composition is eroded with formation water, its initial concentration is violated and, as a result, the stability of the resulting insulating barrier is impaired and the pressure balance is disturbed. Therefore, under conditions of high-intensity absorption, this method is ineffective.

Known grouting foam cement composition containing in parts by weight: cement 37-60; chalk 7-30; surfactant SAS-Syntanol - 0.5; water - 33 (RF Patent No. 2089717, ЕВВ 33/138, publ. 1997).

The main disadvantages of this well-known grouting composition include elongated setting time and insufficient strength of grouting stone, due to the fact that there are no accelerators for hardening periods, and chalk, being an inert additive to cement, does not participate in the hydration process. In the presence of a constant overflow in conditions of high-intensity absorptions, the use of a well-known grouting composition for forming an insulating screen is inefficient, because it will blur.

The closest to the recipe of the proposed aerated grouting mortar in terms of features is a grouting foam cement composition, including a base base containing in parts by weight: cement 97.0-99.0; finished glass microspheres 1.0-3.0; Surfactant 0.5-0.7; sulfafel 0.3-0.4; calcium chloride 3.5-4.0; water 50.0 (RF Patent No. 2176308, ЕВВ 33/138, publ. 2001). The well-known grouting composition is effective in conditions of abnormally low reservoir pressures by reducing the setting time, increasing strength and reducing the gas permeability of the formed cement stone.

The disadvantages of using this composition in the intervals of high-intensity absorption are as follows. Often concomitant with catastrophic absorption, overflows of formation fluid can wash away the known foam cement composition established in the overflow interval. To fix the composition in the zone it is necessary that it be indelible or possess strong adhesive properties. This composition can become indelible only after curing for several hours, and it is practically impossible to achieve instant setting of foam cement compositions. In this case, the effectiveness of insulation work under conditions of high-intensity absorption decreases sharply.

The single technical result achieved by the proposed group of inventions is to reduce the time of insulation work, to ensure reliable insulation in the conditions of catastrophic absorption by reducing the absorption intensity by increasing the viscoelastic characteristics of the compositions used and the strength of the formed cement stone.

To achieve the indicated technical result, a method for isolating high-intensity absorption intervals in a well is proposed, which includes injecting a cement mortar and a polymer composition into the absorption interval, the inventive cement first injecting a cement mortar and then a polymer composition, using an aerated cement slurry, which contains a basic base in the following ratio of components, parts by weight:

Portland cement 85-100 Aluminosilicate Microspheres up to 15 Foaming agent - anionic Surfactant based resin and naphthenic acids 0.1-0.3 Setting accelerator 4.0-7.0 Water 50-60,

and additionally, a gaseous agent in an amount providing a density of aerated grouting composition of 800-1000 kg / m ³ , and a polymer-cement paste obtained by mixing composition I containing, parts by weight, is used as a polymer composition.

Astringent 100.0 Polyacrylamide up to 0.3 Setting accelerator 5.0-8.0 Water 40-50

Composition II is a 0.7-1.2% aqueous solution of polyacrylamide, and as a binder, the first composition contains Portland cement or its mixture with bentonite clay powder in a mass ratio of (96.0 ÷ 99.8) :( 4, 0 ÷ 0.2), respectively.

As an accelerator of setting time, the basic base of aerated grouting composition contains sodium chloride or calcium chloride.

Composition I of polymer cement paste additionally contains a filler - a large-sized 1-5 mm swellable polymer in an amount of 1.0-2.0 wt.h. As a large 1-5 mm swellable polymer, the first polymer cement paste composition contains an acrylic polymer or polysaccharide. As an accelerator of setting time, composition I contains sodium chloride or calcium chloride, or sodium carbonate.

To achieve a single technical result of the claimed group of inventions, an aerated grouting composition is proposed on a basic basis, including Portland cement, surfactant surfactant - foaming agent, microspheres, setting accelerator and water, moreover, according to the invention, as a surfactant foaming agent, the base composition contains anionic surfactants based on resin and naphthenic acids, as microspheres - aluminosilicate microspheres, in the following ratio of components, parts by weight:

Portland cement 85-100 Aluminosilicate Microspheres up to 15 Specified Foaming Agent 0.1-0.3 Setting accelerator 4.0-7.0 Water 50-60,

wherein the solution additionally contains a gaseous agent in an amount providing a density of aerated grouting composition of 800-1000 kg / m ³ .

The achievement of the technical result is ensured by the following.

When isolating catastrophic absorption zones, it is important to balance the well-formation system, which directly depends on the density and visco-plastic properties of the used insulation compositions. In case of catastrophic absorption, the movement of insulating compounds in a porous medium must necessarily be complicated by additional resistances with an increase in viscosity at high shear rates. Viscoelastic compounds are characterized by such properties. Given that the plastic viscosity of aerated grouting compositions under normal conditions is 3-4 orders of magnitude different from the viscosity of conventional cement mortars and their density due to the presence of the gas phase (the compositions are obtained by aerating the base) is low, therefore, under conditions of pressure reduction, they have the ability to expand . This is the advantage of aerated systems when choosing insulation compositions for zones of high-intensity and catastrophic absorption. When viscoelastic compositions move in channels with a large effective cross section, the resistance sharply increases according to a power law, which leads to a decrease in the penetration depth into these channels and a more uniform filling of pores in the near-well zone of the wellbore.

The choice of a specific formulation and the injection mode with aeration of the basic base of the grouting composition is determined by the calculated data depending on the absorption pressure, the depth of the isolation interval, its power and injectivity. If there is a constant flow during catastrophic departures, the use of only one aerated cement slurry for forming an insulating screen is inefficient, because it will blur. To fix the insulating screen from aerated grouting mortar, it is necessary to additionally use indelible polymer-cement paste with short setting time. The proposed method provides as a crushing pack for aerated grouting mortar to use quick-hardening polymer-cement paste, consisting of two compositions sequentially injected into the well.

The formulation of both compositions of polymer cement paste for specific field conditions is determined by the initial plastic strength in accordance with the results of hydrodynamic studies of the absorbing formation and the values of repression on the formation during further drilling and fastening. If necessary, a certain size of fillers is selected and introduced into it.

Due to the proposed sequence of operations in the claimed method and the use of aerated cement slurry and polymer-cement paste for its implementation with the claimed component content of their formulations, reliable isolation is ensured in the conditions of catastrophic absorption by reducing the intensity of absorption and reducing the time of insulation work.

The proposed method is illustrated in the drawing, which shows a schematic diagram of the equipment strapping, with which the inventive method is implemented.

When implementing the proposed method in the field, carry out the following operations in the following sequence:

- the proposed method is recommended for use in wells characterized by zones of high-intensity absorption, for example, above 5 m ³ / h;

- equipment binding at the well is carried out in accordance with the drawing. Compressor 1 is bound to an aerator 3. At the outlet of the air duct from compressor 1, a check valve 2 must be installed. Two cementing units 4 and 5 and a mixer 8 with a dry mixture (for sequential preparation and pumping of the first base of aerated cement slurry and then polymer cement paste) are tied through the tee to the line at the well 6.

- drill pipes are lowered into the well 6 and installed above the absorption zone for pumping the used insulating compounds into the interval of the absorption zone;

- the basic base of the grouting composition, consisting of Portland cement, aluminosilicate microspheres, a foaming agent, setting accelerator and water after mixing is pumped into averaging tank 7 and mixed there until the properties stabilize for 15-20 minutes;

- using a cementing unit 4 and compressor 1 through an aerator 3 with a calculated degree of aeration, which provides a composition with a density of 800-1000 kg / m ³ , the calculated amount of aerated cement slurry is pumped into the well;

- then, on the surface of the cement mixing machine 8, using the cementing unit 5, the first composition of the polymer cement paste is closed, consisting of Portland cement, bentonite clay powder, polyacrylamide, a filler - a large 1-5 mm swellable polymer (if necessary), an accelerator of setting time and water;

- using a cementing unit 5, the calculated amount of composition I of polymer cement paste is injected into the well 6, bypassing the aerator, while a polyacrylamide solution (composition II of polymer cement paste) of the required concentration is simultaneously pumped into the line from the cementing unit 5 to form indelible tampons. During injection through the tanks of the cementing unit, it is necessary to control the flow rate of the paste and the pressure on the cementing unit;

- after completion of the injection, the work in the well 6 is suspended for at least 12 hours while waiting for the cement to harden (OZC). For selected samples of polymer cement paste and aerated grouting composition, it is necessary to control their setting;

- at the end of the time of the OZZ in the well, the static and dynamic level of the insulating material is measured and the depth of the "head" of the cement bridge is determined. After which a conclusion is issued on the success of the isolation work.

Aerated cement slurry and polymer cement paste were tested in laboratory conditions. The following substances were used for their preparation:

- Portland cement brands PTsT-50, PTsT-100; PCT 1G-CC-1;

- aluminosilicate microspheres (TU 21-2237-94);

- bentonite clay powder (TU 480-1-334-91);

- polyacrylamide brand Praestol 2530 (TU 2216-001-40910172-98);

- filler - large-sized 1-5 mm swellable polymer of acrylic series B 615-3 or polysaccharide Camcel 600 Standard;

- foaming agent:

- Foaming agent “Penostrom” a mixture of anionic surfactants - synthetic products from surface-active and auxiliary substances based on resin and naphthenic acids, produced by LLC “SPO Shield” (Schebekino) according to TU 0258-001-22299560-97;

- PB-2000 foaming agent is produced by Ivkhimprom OJSC (Ivanovo) - an aqueous solution of a mixture of anionic surfactants based on resin and naphthenic acids with hydrophobic radicals with the addition of a foam stabilizer, with a density at 20 ° C in the range of 1000-1200 kg / m ³ ; pH in the range of 7-10;

the multiplicity of the foam is not less than 7; foam stability not less than 360 sec;

- TsPO-1 foaming agent according to TU 2482-040-40912231-2006; a surfactant complex based on resin and naphthenic acids with the addition of a foam stabilizer, manufactured by PSK Burtekhnologii LLC, with a density of 1020-1090 kg / m ³ , foam multiplicity of 3% aqueous solution of at least 4.5; foam stability not less than 270 sec;

- Foaming agent “Morpen”, a mixture of anionic surfactants based on resin and naphthenic acids with the addition of a foam stabilizer, produced by LLC “SPO Shield” (Schebekino) according to TU 0258-001-01013393-94; a density of 1050-1200 kg / m ³ , the foam multiplicity of a 6% aqueous solution of at least 65; foam stability not less than 600 sec;

- setting time accelerator:

- sodium chloride TU (2152-097-00209527);

- calcium chloride (TU 2123-020-53501222-2001);

- sodium carbonate (GOST 51100-85);

- technical water.

An example of the preparation of aerated cement slurry with a density of 900 kg / m ³ . They took 900 g of Portland cement grade PTsT-50; 100 g of aluminosilicate microspheres; 50 g of CaCl ₂ and 500 g of water. The base solution was shut with a density of 1650 kg / m ³ . Then, after determining the density and spreadability, while stirring the solution at a speed of 250 rpm, 3 g of TsPO-1 foaming agent was introduced with the simultaneous supply of a gaseous agent - air. Aeration was carried out until the density of aerated grouting composition was achieved.

900 kg / m ³ . In this case, an aerated cement slurry prepared from the following basic base was obtained, parts by weight: portland cement PCT 50 - 90.0; aluminosilicate microspheres - 10.0; foaming agent TsPO-1-0.3; CaCl ₂ -5.0; water 50.0.

These solutions with a different quantitative ratio of the components were prepared in a similar manner.

Subsequently, the determination of water separation, setting time and strength of cement stone from the obtained aerated cement slurry was carried out according to standard methods in accordance with GOST 26798.1,2-96.

An example of obtaining a polymer cement paste from two compositions. To prepare composition 1, 960 g of Portland cement grade PTs-50 were taken; 40 g of bentonite clay powder; 2 g of dry polyacrylamide, 20 g of filler - swellable acrylamide B 615-3, 50 g of calcium chloride and 400 ml of water. The cement mixture (composition I) was closed with a density of 1880 kg / m ³ . In a separate container, a 1% (by weight) aqueous solution of polyacrylamide was prepared (composition II). Without stopping the mixing of the cement mixture (composition I) after obtaining a homogeneous solution and measuring its density and spreadability, 100 ml of composition II - 1% solution of polyacrylamide were portioned into it. In the process of mixing received polymer-cement paste of the following General composition, mass.h:

Portland cement - 96.0; bentonite clay powder - 4.0; polyacrylamide - 0.3; filler - large-sized 2-3 mm swellable polymer of acrylamide B 615-3 - 2.0; calcium chloride - 5.0; water - 50.

A polymer cement paste with a different proportion of components was prepared in a similar manner.

During laboratory tests, the following properties were established for the implementation of the proposed method of polymer-cement paste: density, spreadability, plastic strength, density, water resistance, setting time.

The determination of density, spreadability and setting time was carried out according to standard methods in accordance with GOST 26798.1,2-96.

The determination of the remaining indicators was carried out in accordance with:

- plastic strength with GOST 1440-42

- densities with GOST 310-41

- water resistance with the "Methodology for determining the water resistance of grouting compositions", Perm, PermNIPIneft, 1980.

Data on the content of components of aerated cement slurry and its properties are shown in table 1.

Data on the content of the components of polymer cement paste and its properties are shown in table 2.

The data shown in table 1 show that aerated cement slurry is characterized by the following properties:

- the density of the cement slurry (800-1000 kg / m ³ ) is sufficient to create the balance of the well - reservoir in conditions of high-intensity absorption;

- the time until the end of setting provides the possibility of carrying out a technological operation and the possibility of forming a cement stone in a short time (up to 5 hours);

- the strength of the cement stone guarantees the indelibility of the cement stone and temporary isolation of the formation.

The data shown in table 2 show that the polymer cement paste is characterized by the following properties:

indicators of plastic strength provide the ability to pump the composition during the time required for work;

high water resistance of the paste allows you to maintain an insulating barrier during intense overflow of formation fluid.

The inventive method of isolation was carried out in the field at one of the wells of the Perm Prikamye. The initial data for the work were as follows:

bit diameter 490.0 mm descent depth: conductor 426 mm direction 324 mm 50 m depth of onset 44.5 m well fluid density 1020 kg / m ³ static level 28 m temperature at a depth of 50 m / 70 m 5 ° C absorption rate catastrophic

Based on the initial data, a Work Program was compiled, in which the degree of aeration, the regimes and volumes of injection of insulating solutions were calculated in accordance with the methodological manuals and guidelines based on the specific thermobaric conditions of the well in the event of absorption.

In accordance with the specified Work Program, materials, reagents were delivered to the well and the technical equipment necessary for carrying out the technological operations was delivered.

In the process of isolation were used:

1. Cementing unit ЦА-320 - 2 units

2. The mixer US-6-30 - 2 units.

3. Compressor 2GM2.5-5.101 / sealant - 1 unit

4. The averaging capacity of USO-20 is 1 unit.

The preparation of aerated grouting composition with a density of 850 kg / m ^{3 was} carried out in the following order:

- in a measuring unit of the cementing unit 4, 480 kg of calcium chloride (6% of cement) were dissolved in 4 m ^{3 of} water;

- in the mixing machine 8 through the auger was packed: 7.0 tons of cement; 1.0 t of aluminosilicate microspheres with a concentration of: 1 kg of cement 140 kg of microspheres. Then the mixer was grinded;

- the prepared mixture of components was pumped into averaging tank 7 with a mixing device;

- a foaming agent in an amount of 3.0 l per 1 m ^{3 of} cement mortar was introduced into the prepared mixture, mixed in the averaging tank USO 7, obtaining 7 m ^{3 of the} base base with a density of 1650 kg / m ³ ;

- further cementing unit 4 was pumped into the well 6 of the base base at the 3rd speed with a capacity of 12.4 l / s;

- during pumping, air was supplied by compressor 1 to the base base with a calculated degree of aeration at a flow rate of 2 m ³ / min to obtain an aerated cement slurry with a density of 850 kg / m ³ ;

- the injection time of the specified composition was about 10 minutes;

- during injection, the flow rate of the base base and the pressure on the cementing unit 4 were controlled.

Preparation of polymer cement paste - 5 m ³ :

- first, a cement mortar (composition I) was prepared, for which 7.2 tons of cement and 300 kg of bentonite were packed into mixer 8 and refilled. In the meter of the cementing unit 4, 4 m ³ of mixing water with calcium chloride of 10% concentration was prepared. Cement mortar (composition I) with a density of 1920 kg / m ^{3 was} closed in an amount of 5 m ³ ;

- was also prepared in a separate container of the cementing unit 5 1% solution of polyacrylamide (composition II);

- further, the resulting cement mortar was pumped out by the cementing unit 4 into the well with a productivity of 8.2 l / s, and at the same time, the prepared polyacrylamide solution was portioned into the line from a separate container of the cementing unit 5, i.e. polymer cement paste was pumped into the well;

- in the process of pumping, a sample of polymer-cement paste was taken, which determined the time of formation of the tampon with the required properties and the time of its hardening before stone formation;

- 20 minutes after pumping into the well, the specified paste became non-pumpable, and after 1.5 hours it hardened. The dynamic level was established at a depth of 5 m. The “head” of the cement bridge made of polymer-cement paste was found at a depth of 10 m;

- Further, the well was left at the OZZ. Then the drilling of the well was continued. Catastrophic absorption was absent.

Thus, the implementation of the proposed method of isolation in the field using the inventive aerated cement slurry and polymer cement paste showed the effectiveness of its use.

Claims (6)

1. The method of isolating the intervals of high-intensity absorption in the well, including the injection into the absorption interval of the cement grout and polymer composition, characterized in that the cement grout is first injected, then the polymer composition, while an aerated grout is used as the cement grout the base composition, wt.h:
Portland cement 85-100 Aluminosilicate Microspheres up to 15 Foaming agent - anionic surfactant - based on resin and naphthenic acids 0.1-0.3 Setting accelerator 4.0-7.0 Water 50-60
and additionally, a gaseous agent in an amount providing a density of said solution of 800-1000 kg / m ³ , and a polymer-cement paste obtained by mixing composition 1, containing, parts by weight:
Cementing agent - Portland cement or its mixture with bentonite clay powder at their mass ratio (96.0 ÷ 99.8) :( 4.0 ÷ 0.2) respectively 100.0 Polyacrylamide up to 0.3 Setting accelerator 5.0-8.0 Water 40-50,
and composition II - 0.7-1.2% solution of polyacrylamide. 2. The method according to claim 1, characterized in that, as an accelerator of terms, said base base contains sodium chloride or calcium chloride. 3. The method according to claim 1, characterized in that, as an accelerator of the setting time, the composition 1 of the polymer-cement paste contains sodium chloride or calcium chloride, or sodium carbonate. 4. The method according to claim 1, characterized in that composition 1 additionally contains a filler - swellable polymer with a particle size of 1-5 mm in an amount of 1.0-2.0 wt.h. 5. The method according to claim 4, characterized in that the acrylic polymer or polysaccharide is used as the swellable polymer. 6. Aerated cement slurry used in the implementation of the method according to claim 1.

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