RU2508307C2 - Grouting mortar for cementing horizontal holes - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: proposed grouting mortar comprises grouting Portland cement PTTS- IG-CC-1, fluid loss reducing agent HYDROTSEM, supersoftener - polyether carboxylate Melflux F or sulphuretted melamine-phenolic resin TSEMPLAST MF, antifoamer POLITSEM DF and setting accelerator, i.e. calcium chloride, and water. It differs from known compositions in that it includes extra mineral additive, i.e. metakaolin or Meta-Mix-1, or CON MIX SF1, or MIKRODUR, at the following ratio of components. Wt %: PTTS IG-CC-1 - 93.35-98.9, HYDROTSEM - 0.1-0.5, said csupersoftener - 0.05-0.3, POLITSEM DF - 0.1-0.3, said mineral additive - 0.5-1.0, calcium chloride - 0.1-2.0, water to water-cement ratio of 0.45-0.55.

EFFECT: higher efficiency of cementing, low filter properties, absence of water separation, required terms of cementation.

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Description

The invention relates to the oil and gas industry, namely to the construction of wells, mainly to cementing production casing located in an oblique direction (with a deviation from the vertical of more than 45 °) and the horizontal part of the barrel.

These wells include sidetracks (with a directional or horizontal part of the trunk), the construction of which is carried out from the stock of previously drilled wells. The ratio of the diameters of the barrel and liner in such wells determines the presence of reduced annular gaps.

A feature of cementing wells in conditions of reduced annular gaps is that special requirements are imposed on the properties of the grouting mortar. With reduced annular gaps, rheology of the cement slurry is important in the cementing process. If in the process of cementing wells with normal annular gaps (more than 20 mm), the rheological characteristics of the cement slightly affect the hydraulic losses that occur during cementing, then with reduced annular gaps, high rheological parameters of the properties of the cement can lead to an emergency in the cementing process.

It is important in the process of cementing wells with reduced annular gaps to have such rheological characteristics of the cement slurry that ensure the trouble-free cementing process and penetration of the cement slurry into hard-to-reach narrow gaps between the well wall and the casing.

The regulation of the rheological properties of the grouting composition is complicated by the fact that when cementing production casing the production formation is isolated. One of the main tasks in this case is the preservation of the productive formation from the negative impact on it of the cement filtrate. Therefore, grouting compositions are treated with filtration reducers. Reducing the filtration of cement mortars in most cases is carried out by thickening the liquid phase of the cement mortar, which inevitably leads to thickening of the cement mortar itself, and, consequently, to increase rheological parameters.

The presence of water separation leads to the fact that after the setting of cement at the upper wall of the well at the contact with the cement ring, a microgap is formed, which can subsequently cause interstratal overflow.

Another reason for the formation of micro-gaps in the cement ring may be the contraction phenomenon characteristic of cement. To compensate for this phenomenon, various expanding additives are added to the cement, the use of which, depending on the activity and concentration can compensate for shrinkage phenomena, make the cement stone expand or strain. The main purpose of the expanding additive in cementing grouting compositions is to compensate for shrinkage and increase the density of contact of cement stone with the surrounding surfaces.

In addition to the expanding additive, it is possible to improve the contact during adhesion of the cement stone to the containing surfaces through the use of adhesive additives, which increase the contact density of the cement stone with the containing surfaces due to the chemical interaction of the contacting surfaces.

When cementing wells with reduced annular gaps, optimization of the above-mentioned properties of grouting compositions, which ultimately affect the quality of the formed cement ring and its contact with the surrounding surfaces, is especially relevant.

Known grouting mortar for cementing oil and gas wells (RF Patent No. 2386660), containing in wt.%: Portland cement 95; condensed silica fume 5; and in excess of 100: polyvinyl acetate dispersion 0.3-0.6, condensed sulphate alcohol distillery vinasse 0.2, polypropylene fiber 6-12 mm long, 14-18 microns in diameter 0.05-0.1. The cement slurry contains water to a water-cement ratio of 0.38-0.42. The known solution provides an increase in the resistance of cement stone to shock loads and an increase in the adhesion of cement stone to bounding surfaces.

However, its disadvantage is that it is designed for moderate temperatures and tested at an appropriate temperature of 75 ° C. In addition, the known solution contains setting retarders, the presence of which lengthens the setting time under normal temperature conditions, which reduces its functionality. In addition, this cement slurry has a low spreadability and high rheological performance, which is unacceptable for cementing small annular gaps.

Also known is a grouting composition for fastening gently sloping and horizontal wells (RF Patent No. 2256775), which is close to the proposed invention for its intended purpose. The objective of the known composition is a comprehensive solution to the problem of high-quality fastening of shallow and horizontal wells and separation of the reservoirs by suppressing the sedimentation process and preventing the precipitation of the solid phase on the lower wall of the barrel and the formation of a channel at the upper wall by increasing the sedimentation stability of the solution to a level at which the SR parameter does not exceed 79%, as well as maintaining the reservoir properties of the reservoir and protecting the near-trunk zone from pollution by filtrate amponazhnogo solution by reducing the fluid loss, while maintaining its normal solution technological parameters ensuring its download prodavku and into the annulus. The well-known grouting composition contains grouting cement, a stabilizing reagent with the function of a decrease in filtration, a mineral additive - sodium chloride or potassium chloride and water.

The disadvantage of this known grouting composition is that it is designed and tested for moderate temperature conditions, i.e. 75 ° C, in addition, the claimed grouting composition has a low spreadability, which can create problems when cementing small annular gaps.

The closest to the proposed technical solution in terms of features is an expanding grouting composition (RF patent No. 2360949), containing in wt.%: Portland cement ПЦТ IG-CC-1 91.3-98.3; HYDROCEM filtration reducer 0.1-0.5; superplasticizer - polyester carboxylate Melflux F or sulfonated melamine formaldehyde CEMPLAST MF 0.1-0.7; defoamer POLITSEM DF 0.1-0.3; setting time accelerator - calcium chloride 0.1-3.0; expanding additive - aluminum oxide and / or calcium sulfoaluminate 0.5-5.0; and water to a water-cement ratio of 0.47-0.78.

A disadvantage of the known composition is the lack of strength properties with a high content of superplasticizer.

The technical result achieved by the present invention is to increase the efficiency of the composition when cementing wells, including shallow and horizontal, with small annular gaps due to increased strength at low concentrations of mineral additives and superplasticizers, while maintaining low rheological and filtration properties, lack of water separation, and providing technologically required setting time.

The specified technical result is achieved by the proposed grouting composition for cementing horizontal boreholes, including grouting portland cement ПЦТ IG-CC-1, a filter reducing agent HYDROCEM, superplasticizer - Melflux F polyester carboxylate or ZEMPLAST MF sulfonated melamine formaldehyde, chloramate slurry and calcium-based antifoaming agent POLITEL DEMIT - , characterized in that it additionally contains a mineral additive: metacoalin, or Meta-Mix-1, or CONMIX SF1, or MIKRODUR, in the following ratio ENTOV, wt.%:

cement PCT IG-CC-1 95.9-98.9 HYDROCEM filtration reducer 0.1-0.5 specified superplasticizer 0.05-0.3 antifoam POLICE DF 0.1-0.3 specified mineral supplement 0.5-1.0 calcium chloride 0.1-2.0 water to water-cement ratio 0.45-0.55

The use of the proposed grouting composition will allow cementing wells with small annular gaps without excessive hydrodynamic losses, which will reduce hydraulic pressures in the cementing process, and accordingly pressure on the reservoir during cementing of production casing. In addition, this will ensure penetration of the composition into narrow gaps between the well wall and the casing (production) string. Achieving the indicated result is ensured by the low rheological characteristics of the inventive grouting composition: the plastic viscosity of the grouting composition does not exceed 180 MPa * s; dynamic shear stress of not more than 139 dPa, even at a lower concentration of superplasticizer compared to the prototype.

In the interval of the reservoir, the use of the proposed cementing composition with low filtration will protect the reservoir from exposure to filtrate cement. The absence of water separation will eliminate the formation of a fluid-conducting channel between the well wall and the rock during the formation of cement stone.

The combination of properties attached to the inventive grouting composition will allow for high-quality and effective cementing of wells with difficult cementing conditions, namely, shallow and horizontal wells with small annular gaps.

The achievement of the specified technical result is ensured by a certain selection of components (qualitative and quantitative) in the inventive grouting composition, i.e. this result is synergistic.

Cement of the PTsT grade IG-CC-1 is used as the basis for obtaining this grouting composition. Advantages of using this type of cement: good compatibility with various additives; high strength properties; low permeability of cement stone; sulfate resistance.

Introduction to the grouting composition of the mineral additive in combination with other components will allow for the claimed quantitative ratio, due to changes in the structure of cement stone: to improve the adhesive properties; reduce cement filtration; exclude water loss; reduce sedimentation phenomena; improve rheological properties. The main effects of introducing a mineral additive into the grouting composition are microfilling and pozzolanic (chemical activity with respect to Ca (OH) ₂ ).

As a finely dispersed mineral additive in the proposed composition can also be used metacoline, or Meta-Mix-1, or CONMIX SF1, or a binder of very fine dispersion: MIKRODUR.

Metacoaline is a dehydroxylated form of the clay mineral kaolinite; it is formed when pure kaolin is heated to temperatures between 1,200 F and 1,750 F (650 ° C - 900 ° C). This treatment, also known as calcination, fundamentally changes the particle structure, creating a highly reactive amorphous pozzolan. Metakaolin comes in two forms: in the form of clinker and in powder form.

The MetaMix-1 modifier is a highly active mineral complex (a mixture of metakaolin and silica fume), the active ingredient of which is metacoalin, which has pozzolanic activity (the ability to bind lime) at the level of 1050-1100 mg / g. Due to its clay nature, Metamix-1 improves the ductility and cohesion of mortar and concrete mixtures.

CONMIX SF1 is a highly effective, dry silica fume additive for concrete. This is an ultra-thin spherical super-active mineral additive that complies with ASTM C1240, based on silica. The smallest particle size of CONMIX SF1 allows them to fill the cement matrix, thereby compacting the cement stone. The specified silica fume additive is obtained by grinding high purity quartz with coke in electric arc furnaces in the production of silicone and ferrosilicon alloys. Its main component is silica of amorphous modification. It is a highly effective natural pozzolanic material. This is due to the fact that silica fume is very finely ground, and has a high concentration of silica. Silica fume in the presence of moisture interacts with cement to form calcium hydrosilicate, which has a more developed spatial structure.

MIKRODUR influences the strength properties of cement stone. The diameter of the MIKRODUR grains is 6-10 times smaller than the particles of the cement clinker itself. Due to the small size (grain diameter <6-10 μm) of the particles and the smoothly selected particle size distribution, the MIKRODUR suspension has a fluidity comparable to the fluidity of the water, even with a minimum water-cement ratio. MIKRODUR is a powder with a specially selected mineral and particle size distribution. This provides high water holding capacity (W / D of MIKRODUR material up to 6.0) and rheological characteristics commensurate with water characteristics. Due to these properties, the MIKRODUR additive in the proposed cement composition allows us to provide the necessary rheological characteristics of the cement composition without increasing the water-cement ratio.

MIKRODUR additive to cement allows you to change the structure of the cement stone formed due to a denser packing of particles in space. Having particles smaller than cement, MIKRODUR fill the inter-pore space and is a reinforcing material in the cement stone. The plasticizer used in the grouting composition increases the dispersion, allowing more efficient use of the different sizes of particles, maximizing the density of the formed structure of cement stone. MIKRODUR is a material homogeneous with cement, just as cement participates in hydration processes, forming strong bonds in cement stone due to hydration formations.

As a decrease in filtration in the proposed grouting composition, hydroxyethyl cellulose of the HYDROCEM brand is used with a viscosity of a 1% aqueous polymer solution of not more than 20 mPa * s. The use of such hydroxyethyl cellulose allows one to obtain low filtration, sedimentation processes are removed, which ensures zero water separation of the resulting cement slurries. And due to the synergistic effect when interacting with other components, the specified filtration index reaches a quantitative value corresponding to the Schlumberger classification of low and ultra-low filtration.

The addition of a plasticizer to the grouting mixture allows you to adjust the rheological properties of the cement using a highly effective plasticizer - polyester carboxylate Melflux F or sulfonated melamine formaldehyde CEMPLAST MF. Moreover, its concentration is halved compared to the prototype, but this not only did not worsen the rheological properties of the composition, but even improved somewhat (for example, the flowability increased, the plastic viscosity and dynamic shear stress decreased).

Melflux F, manufacturer: Degussa Constraction Polymers (SKW Trostberg, Germany); chemical composition - a powder product obtained by spray drying based on a modified polyether carboxylate. Technical data: form - yellowish powder; bulk density - 400-600 g / l; heat loss - max. 2.0 wt.%; 20% solution at 20 deg. C has a pH of 6.5-8.5. Features: - highly effective dispersant; - reduces shrinkage; - effective in a wide temperature range.

ZEMPLAST MF, the active component of which is sulfonated melamine formaldehyde, with a pH of 1% aqueous solution of 8.5-10.5.

The addition of setting time accelerator - calcium chloride, allows to reduce the setting time of cement and increase the strength properties of cement stone at an early stage of hardening.

To obtain the inventive grouting composition in laboratory conditions, the following substances were used:

- grouting portland cement of the PTsT brand IG-SS-1, GOST 1581-96;

- hydroxyethyl cellulose brand HYDROCEM N, C according to TU2231-009-40912231-2003;

- a superplasticizer based on polyether carboxylates: CEMPLAST MF (b) according to TU 2223-011-40912231-2003;

- Melflux F superplasticizer (sulfonated melamine formaldehyde or polycarboxylic esters), a water-reducing additive according to the degree of plasticization in accordance with GOST 242111-91 belongs to the group of superplasticizing agents, manufacturer: Degussa Constraction Polymers (SKW Trostberg, Germany); powder product obtained by spray drying based on a modified polyether carboxylate. Technical data: form - yellowish powder; bulk density - 400-600 g / l; heat loss - max. 2.0 wt.%; A 20% solution at 20 ° C has a pH of 6.5-8.5. Features: highly effective dispersant; reduces shrinkage; effective over a wide range of temperatures;

- defoamer POLITSEM DF - modified organosilicon reagent according to TU 2228-010-40912231-2003;

- reinforcing fiber: polyacrylic fiber: Panacea, FPAC 236/040, Fibrocem B TU 2458-058-40912231-2009;

- defoamer POLITSEM DF - modified organosilicon reagent according to TU 2228-010-40912231-2003;

- calcium chloride, GOST 450-79;

- technical water.

- Metakaolin, which is a dehydroxylated form of the clay mineral kaolinite, is formed when pure kaolin is heated to temperatures between 1,200 F and 1,750 F (650 C - 900 C). TU U 14.2.00191916-001: 2005; TU U 14.2.36363275-001: 2009.

- MetaMix is a complex modifier with a multifunctional effect, which is used in the manufacture of concrete and mortar mixes, the main components of which are metakaolin and silica fume, manufactured by MetaRus LLC (Moscow) Tu 5743-001-68989904-11.

- Silica fume is a highly effective natural pozzolanic material. This is due to the fact that silica fume is very finely ground, and has a high concentration of silica. TU 5743-048-02495332-96, TU 5743-048-02495332-96;

- CONMIX SF1 silica powder - an ultra-thin spherical superactive mineral additive that meets the ASTM C1240 standard, created on the basis of silica, is produced from a biological product and does not have a harmful effect on the environment;

- MIKRODUR - "MIKRODUR R-X" - a particularly finely dispersed mineral binder with a guaranteed smooth change in particle size distribution. Mikrodur is produced by air separation of dust by grinding cement clinker. The Mikrodur R-X manufacturing technology was developed and mastered by INTRA-BAVGmbH specialists together with the Dyckerhoff concern (Wiesbaden, Germany and is protected by a European patent).

Example. To prepare the proposed grouting composition in laboratory conditions, 1032.1 g of PCT cement IG-CC-1 was taken, 10.7 g of Metacoalin mineral additive was added, HYDROCEM N hydroxyethyl cellulose was 2.14 g, CEMPLAST MF plasticizer (b) - 1, 61 g, antifoam POLICE DF - 2.14 g, calcium chloride - 21.4. The resulting cement mixture was thoroughly mixed. 475 ml of industrial water was taken as a mixing liquid, based on a water-cement ratio (W / C) of 0.46. After mixing the obtained grouting mixture, a grouting composition was obtained with the following ratio of components, wt.%: Cement - 96.45; Metakaolin - 1.0; hydroxyethyl cellulose HYDROCEM N - 0.2; plasticizer CEMPLAST MF (b) - 0.15; antifoam POLICE DF - 0.2; calcium chloride - 2.0; W / C = 0.46.

Grouting compositions with a different content of components were prepared in a similar way.

In laboratory conditions, the following properties of the inventive grouting composition were investigated:

- density;

- spreadability;

- plastic viscosity;

- dynamic shear stress;

- static shear stress;

- filtering;

- water separation;

- the thickening time of the grouting composition;

- setting time;

and also investigated the following properties of cement stone obtained from the specified composition:

- ultimate strength in bending;

- ultimate compressive strength;

- force ejection of the sample.

Data on the investigated grouting compositions are shown in table 1; data on properties - in table 2.

The data shown in table 2 confirm that the inventive grouting composition meets the technical task, namely: due to indicators characterizing the mobility of the cement mortar: spreadability (230-265 mm) and rheological indicators (plastic viscosity not more than 180 MPa * s; dynamic stress shear is not more than 139 dPa), and, despite the low plasticizer content, the annular space between the rock and the column is completely filled with cement with small gaps. In the process of pumping and selling cement mortar into the annulus due to low rheological parameters, excessive pressures during cementing, depending on the properties of the cement mortar, are eliminated.

Due to the low and ultra-low filtration of the grouting composition, the reservoir properties of the productive formations from the negative effects of the cement filtrate are preserved.

The sedimentation stability of the cement mortar (water separation of not more than 0.1 ml) reduces the risk of micro-gaps in the cement ring, and therefore the likelihood of possible overflows along the cement ring.

The proposed composition has the following advantages over the known prototype:

- bending strength is higher by 29-59% and compressive strength is higher by 24-31%, despite the low content of mineral additives;

- with a more rational use of plasticizer (its concentration is 2–2.33 times lower than that of the prototype), low and ultra-low filtration of grouting composition (12–91 ml) and low rheological parameters are preserved: dynamic shear stress of not more than 139 dPa; plastic viscosity of not more than 180 MPa * s, while the prototype, these indicators are 140-161 dPa and 160-185 MPa * s, respectively.

Due to the above properties, when using the proposed grouting composition in the field, when attaching the column in a shallow and horizontal well, it will be provided:

- reduction of hydrodynamic losses in the cementing process;

- complete filling of the annular space with grouting composition;

- preservation of the reservoir properties of the reservoir from the effects of the filtrate composition;

- tight contact of the cement stone with the surrounding surfaces reduces the likelihood of annular flow along the contact zone of the surface of the cement ring with the rock and column.

Table 1 Data on the content of components in the investigated grouting compositions No. p / p The components of the cement composition, wt.% Cement Mineral supplement HYDROCEM Plasticizer Antifoam POLICE DF Calcium chloride W / C The proposed grouting composition one 98.5 0.5 0.3 0.1 0.1 0.5 0.55 2 97.75 0.5 0.4 0.05 0.3 1,0 0.45 3 98.4 0.5 0.1 0.3 0.2 0.5 0.47 four 98.0 1,0 0.5 0.3 0.3 0.1 0.52 5 98.0 0.5 0.2 0.1 0.2 1,0 0.45 6 96.75 0.7 0.3 0.05 0.2 2.0 0.48 The prototype composition of the patent of the Russian Federation No. 2360940 7 91.3-98.3 Expanding additive 0.5-5 0.1-0.5 0.1-0.7 0.1-0.3 0.1-2 0.47-0.78 Note: 1). As a finely divided additive used: in experiment 1 - Metakaolin; in experiment 2,4 - Meta Mix1; in experiment 3.6 - Conmix SF1; in experiment 5 - Mikrodur. 2). As a plasticizing additive: in experiments 3.5 - Zemplast MF; in experiments 1, 2, 4, 6 - Melflux F. 3). The test temperature was 22 ± 2 ° C.

Claims (1)

Grouting composition for cementing horizontal wellbores, including PTC cementing portland cement IG-CC-1, HYDROCEM filtration reducer, Melflux F superplasticizer-polyester carboxylate or CEMPLAST MF sulfonated melamine formaldehyde, POLITEMEM DF antifoam, accelerating agent, calcium accelerator, and calcium accelerator, which accelerates calcium chloride and it additionally contains a mineral additive - metakaolin or Meta-Mix-1, or CONMIX SF1, or MIKRODUR, in the following ratio, wt.%:
cement PCT IG-CC-1 95.9-98.9 filtration reducer - HYDROCEM 0.1-0.5 specified superplasticizer 0.05-0.3 antifoam POLICE DF 0.1-0.3 specified mineral supplement 0.5-1.0 calcium chloride 0.1-2.0 water to water-cement ratio 0.45-0.55