RU2337124C1 - Grouting mortar base foundation for well cementing - Google Patents

Abstract

FIELD: chemistry, construction.

SUBSTANCE: base foundation contains in wt %: oil-well Portland cement - 95.0-98.0; polyamide fibre or polyamide fibre mix with chrysotile asbestos in proportion 0.3-2.0:1 - 0.5-4.0; superplasticiser - 0.05-0.2; oxyethyl cellulose - 0.1-0.5; setting time accelerant - the rest. Additionally, base foundation may contain antifoamer in amount 0.1-0.2 wt %. As antifoamer base foundation contains POLYCEM DF, as superplasticiser, the superplasticisers of trade marks CEMPLAST MF, C-3, or Melflux, and as setting time accelerant - calcium chloride or sodium chloride.

EFFECT: increase in quality of plugging stone formed due to mechanical properties improvement.

4 cl, 2 tbl, 1 ex

Description

The invention relates to the field of well construction, in particular to cement slurries used in cementing casing strings for oil and gas wells, in cementing productive formations, and in eliminating complications in wells.

The prior art a number of grouting compositions used in cementing oil and gas wells, for example: grouting composition containing Portland cement and overburden of asbestos deposits (RF patent No. 2036298, CL ЕВВ 33/138, from 1995); grouting material for cementing high-temperature wells, containing grouting cement on a slag basis and fibrous filler (patent No. 1010253, CL ЕВВ 33/138, from 1983).

The disadvantage of all these known grouting compositions is that they have insufficient tensile strength and high filtration, which can lead to premature thickening.

Closest to the proposed technical solution for the technical essence is a dispersion-reinforced base base for cement slurry for cementing wells, which contains the ingredients in the following ratio; wt.h:

Silicate and / or chlorosilicate Portland cement one hundred Wollastonite and / or fibrous crystals synthetic calcium or magnesium hydrosilicates 3.0-8.0 A mixture of natural fiber crystals or synthetic minerals, or metal fibers, or fiberglass, or basalt fibers with polypropylene, or kapron or nylon, or polyvinyl alcohol fibers taken in a ratio of 1: 1-2: 1 2.0-4.0 Liquid type silicone polymers oligoorganohydrosiloxanes 0.05-0.25 Organosilicon powders compounds such as allylsiliconates 2.5-8.0 Palygorskite 2.0-6.0.

To prepare the cement slurry, the specified base is dissolved in water, adding the latter in an amount of 45-75 parts by weight.

The disadvantage of this known cement slurry are the following:

- large water separation of cement slurry, which leads to its separation;

- low spreadability, which cannot provide its good pumpability;

- high filtration in conditions of moderate and elevated temperatures, comparable with the rate of filtration of pure cement, which is 600 cm ³ at ΔP = 0.7 MPa, which can lead to premature thickening of the cement slurry.

The technical problem solved by the present invention is to improve the quality of cement slurry obtained from the claimed base base by ensuring its low filtration at the level of filtration of drilling fluids, eliminating water separation, imparting rheological properties that provide shuttering and injection into the well without additional overpressure during cementing , as well as improving the quality of the resulting cement stone due to the regulation of its physical and mechanical properties during compression, bending e, tensile (break), toughness and adhesion properties.

The specified technical problem is provided by the proposed basic base of cement slurry for cementing wells, including Portland cement, reinforcing fiber and plasticizer, while the new one is that it additionally contains hydroxyethyl cellulose and an accelerator of setting time, as Portland cement it contains cement portland cement, as a reinforcing fiber - polyamide fiber or its mixture with chrysotile asbestos with a mass ratio of 0.3-2.0: 1, respectively, and as a plasticizer - super . Lastifikator, with the following ratio of ingredients, wt%:

Grouting Portland cement 95.0-98.0 Polyamide fiber or polyamide fiber blend with chrysotile asbestos 0.5-4.0 Superplasticizer 0.05-0.2 Hydroxyethyl cellulose 0.1-0.5 Setting accelerator Rest.

The base base additionally contains an antifoam POLICEM DF in an amount of 0.1-0.2 wt.%

The base base as a superplasticizer contains superplasticizers of the brand CEMPLAST MF, C-3 or Melflux.

The base base as a setting accelerator contains calcium chloride or sodium chloride.

The achievement of the specified technical result is ensured by a certain selection of ingredients (qualitative and quantitative) in the claimed base basis, i.e. this result is synergistic.

Thanks to the introduction of hydroxyethyl cellulose into the basic base, low filtration is ensured, sedimentation processes are removed, which ensures zero water separation of the resulting cement slurries. And due to the synergistic effect in interaction with other ingredients, the specified filtration rate approaches the level of drilling fluid filtration, which will allow in field conditions when cementing permeable intervals to exclude premature thickening of the cement slurry.

The use of a polyamide fiber or its mixture with chrysotile asbestos as the reinforcing fiber in the proposed base base, along with an increase in the elastoplastic (specific impact strength, brittleness) properties of the cement slurry, increases the strength properties of the resulting cement stone (during compression, bending, rupture and adhesion) with the breed). Polyamide fibers (or their mixture with chrysotile asbestos) in the absorption zone form a network bridge jumper, which contributes to the rapid formation of a filter cake, which prevents the cement mortar from entering the formation. Fibers of different sizes provide the formation of micro- and macro-fittings in a cement stone, which determines the ability of the cement stone matrix to absorb tensile and shock loads. Thanks to this, grouting mortar prepared from the proposed base mixture becomes universal and can be used in various reservoir conditions:

- for cementing reservoirs;

- to eliminate absorption in karst sediments and large caverns;

- for cementing technical and production casing, where the section of the wells is composed of highly permeable formations, which eliminates the possibility of using lightweight grouting compositions and devices for step cementing. The latter quality is especially valuable since allows you to use the same solution in different cycles of well construction, which increases the efficiency of construction.

Introduction to the proposed basic base of antifoam provides a reduction in foaming, which favorably affects the work of cementing equipment.

The mixture of reinforcing fibers includes chrysotile asbestos, for example, grade A7-450, and polyamide fiber, for example, grade RA. The ratio of fibers in the mixture can vary depending on geological and technical conditions and have the following ratios: polyamide fiber: chrysotile asbestos as 0.3-2.0: 1.

The use of superplasticizer in the proposed basic basis allows you to modify the structure of the cement slurry, compacting it, which in turn contributes to an increase in the strength of cement

To obtain the claimed base base and cement slurry from it in laboratory conditions, the following substances were used:

- grouting portland cement of the PTsT brand IG-CC-1;

- hydroxyethyl cellulose brand HYDROCEM N, C;

- superplasticizer brands: CEMPLAST MF (melamine-containing reagent) according to TU 2223-011-40912231-2003; C-3 (sodium salt of the condensation product of naphthalenesulfonic acid with formaldehyde according to TU 6-14-625089) and Melflux - polyester carboxylates (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, manufactured by Degussa Constraction (SKW Trostberg, Germany);

- a polyamide fiber, for example, grade RA or R6,6, is obtained by polymerization of a dibasic acid and diamine. The term "nylon" refers to a group of polyamide resins, which are long chain amides in which the amide group forms an integral part of the main polymer chain. All nylons are famous for their high resistance to alkaline environments, as well as to common solvents. They have good abrasion resistance combined with a very low coefficient of friction. Their high melting point (250 ° C) makes them particularly suitable for various applications where a certain level of fire resistance is specifically required. Polyamide is also known for its hydrophilic properties; this quality provides excellent re-dispersibility in various mineral environments. Polyamide fibers are strong, tough and elastic, which makes them especially suitable for reinforcing thin elements based on mineral binders;

- chrysotile asbestos - dusty grades A7-450; Chrysotile asbestos mineral is characterized by the following physical and technical indicators:

- the chemical composition approximately corresponds to the theoretical formula 3MgO · 2SiO ₂ · 2H ₂ O;

- density 2.4-2.6 g / cm ³ ;

- alkali resistance is high;

- acid resistance is weak;

- the content of consistency moisture of 13.46%.

- setting accelerator: calcium chloride, sodium chloride;

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

- water technical hardness not less than 5 mEq / l.

The possibility of carrying out the claimed invention is confirmed by the following example.

Example. To obtain the proposed basic base in laboratory conditions, 950 g of cement-based portland cement of the PTsT grade IG-CC-1 was taken, 10 g of polyamide fiber, 5 g of chrysotile asbestos, 4 g of hydroxyethyl cellulose - HYDROCEM N, 1 g of superplasticizer - CEMPLAST MF were added to it. The resulting cement composition was thoroughly mixed. Calcium chloride accelerator of setting time in the base base was added in an estimated amount of 30 g to the mixing liquid (the traditional way of preparing cement slurries from the base base). As a result, the basic basis of the following ingredient composition was obtained, wt.%: Cement Portland cement - 95; a mixture of polyamide fiber and chrysotile asbestos (in a ratio of 0.5: 1, respectively) - 1.5; superplasticizer - 0.1; hydroxyethyl cellulose - 0.4; calcium chloride - 3.

Basic bases with different contents of ingredients were prepared in a similar way.

Further, from the obtained base base, a cement slurry was prepared by mixing it in industrial water at a water-cement ratio of 0.47. Calcium chloride (an accelerator of setting time in the base basis) in an estimated amount of 30 g was previously dissolved in a mixing liquid.

During laboratory tests, the following properties of the cement slurry prepared from the claimed base stock were determined:

- density;

- spreadability;

- plastic viscosity;

- dynamic shear stress;

- filtrate recovery;

- water separation

and also determined the following properties of cement stone:

- specific impact strength;

- tensile strength at break, in bending, in compression;

- force ejection of the sample.

Data on the ingredient composition of the investigated basic foundations are given in table 1. Data on the properties of the grout and grout stone are shown in table 2.

Table 1 Data on the ingredient composition of the proposed base base №№ The ingredient composition of the base base, wt.% Water-cement ratio prepared from the base of cement slurry Grouting Portland Cement Polyamide fiber Chrysotile Asbestos Hydroxyethyl cellulose Antifoam agent Super plasticizer Setting accelerator one 95 0.5 - 0.5 0.2 0.05 3.75 0.44 2 95 0.5 - 0.5 - 0.05 3.95 0.44 3 96 0.5 1,0 0.3 - 0.1 2.1 0.47 four 95 1,0 0.5 0.5 - 0.1 2.9 0.5 5 97 1,0 1,0 0.1 - 0.2 0.7 0.53 6 98 0.7 0.5 0.1 0.1 0.05 0.55 0.48 7 95 2.0 - 0.1 - 0.2 2.7 0.6 Note: 1. As a superplasticizer used in experiment 1, 3 - C-3; in experiment 2 - Melflux; in the rest - ZEMPLAST. 2. As an accelerator of the setting time in experiments 1-4, calcium chloride was used; in the rest - sodium chloride. 3. In experiments 1,6 as an antifoam used POLICE DF

The data shown in tables 1 and 2 show that the proposed base base allows you to get cement slurries, characterized by the following positive qualities:

- low filtration;

- sedimentation stability;

- properties characterizing the mobility of the cement slurry (plastic and dynamic viscosity, spreadability), allow the shutter and injection of cement slurry into the well without additional overpressure during cementing.

And the cement stone formed from these cement slurries is quite strong and retains this strength under various loads (bending, compressing, tensile), is characterized by increased elastoplastic properties, which reflect: specific impact strength and brittleness of the cement stone, which will allow to increase the fracture toughness of the cement ring during the period of perforation and will ensure the integrity of the cement stone during crimping and further drilling of the well.

Due to the indicated properties, grouting mortars obtained from the claimed basic base will allow to maintain the insulating properties of cement stone after perforation in the well.

Claims (4)

1. The basic base of cement slurry for cementing wells, including Portland cement, reinforcing fiber and plasticizer, characterized in that it additionally contains hydroxyethyl cellulose and an accelerator of setting time, as Portland cement it contains grouting Portland cement, as a reinforcing fiber - polyamide fiber or its mixture with polyamide fiber chrysotile asbestos with their mass ratio of 0.3 ÷ 2.0: 1, respectively, and as a plasticizer - superplasticizer in the following ratio of ingredients, wt.%: cement Portland cement 95.0-98.0 polyamide fiber or polyamide fiber blend with chrysotile asbestos 0.5-4.0 superplasticizer 0.05-0.2 hydroxyethyl cellulose 0.1-0.5 setting accelerator rest. 2. The base base according to claim 1, characterized in that it further comprises an antifoam POLICEM DF in an amount of 0.1-0.2 wt.%. 3. The base base according to claim 1, characterized in that as a superplasticizer it contains a superplasticizer brand CEMPLAST, C-3 or Melflux. 4. The basic basis according to claim 1, characterized in that as the accelerator of the setting time, it contains calcium chloride or sodium chloride.