RU2810354C1 - Backfill compound - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: cement mixtures intended for cementing oil and gas wells covering intervals of permeable formations at elevated temperatures. The cement composition includes, wt.%: Portland cement PCT-I-50 62.1-62.2; water 31.2-31.4, as carbon black, a mixture of nanoadditives 0.3-0.45; silica smoke 6.0-6.4. The mixture of nanoadditives comprises Graphene Oxide GLC-GO, Carbon nanotubes CAS 308068-56-6, Nanosilica OSCh CAS 112926-00-8 at the following ratio in wt.% of the mass of the cement composition: 0.1:0.1:0.1, or 0.15:0.1:0.1, or 0.15:0.15:0.1, or 0.15:0.15:0.15 respectively.

EFFECT: increasing the efficiency of well casing under conditions of elevated temperatures.

1 cl, 1 tbl, 16 ex

Description

The invention relates to the oil and gas industry, in particular to cement mixtures intended for cementing oil and gas wells covering intervals of permeable formations at elevated temperatures.

A known composition for the production of building materials (RU patent No. 2345968, published on February 10, 2009), containing cement, sand, water and carbon nanomaterial - soot, obtained by the electric arc method and containing 7.0% carbon nanotubes, with the following ratio of components, wt. %: cement - 20-30, filler - 50-70, carbon nanomaterial - 1-2, water - the rest.

The disadvantage of the known composition is the difficulty of industrial production of soot using the electric arc method in large volumes.

A composition based on mineral binders is known (patent RU No. 2233254, published on July 27, 2004), including a mineral binder selected from the group including cement, lime, gypsum, or mixtures thereof and water, additionally containing carbon clusters of the fulleroid type with the number of carbon atoms 36 and more with the following ratio of components in the composition (wt.%): mineral binder - 33-77; carbon clusters of the fulleroid type - 0.0001-2.0; water - the rest. As fulleroid-type carbon clusters, the composition may contain polydisperse carbon nanotubes, polyhedral multilayer carbon nanostructures with an interlayer distance of 0.34-0.36 nm and a particle size of 60-200 nm, or a mixture of polydisperse carbon nanotubes and C60 fullerene.

The disadvantages of this composition are the complex component composition and the difficulty of industrial production of fulleroid-type carbon clusters in large volumes.

A known composition is based on mineral binders (RU patent No. 2447036, published on April 10, 2012), including Portland cement, sand, water and carbon material, and as a carbon material it contains an aqueous suspension of cavitation-activated carbon-containing material - KAUM, which includes multilayer carbon nanostructures with an interlayer distance of 0.34-0.36 nm and a particle size of 60-200 nm, polydisperse carbon tubular formations with sizes of 100,000 Å-1,000,000 Å, hydrogenated carbon fractal structures with sizes of 1000 Å-1,000,000 Å and active loose carbon with sizes defective graphite microcrystallites, approximately equal to 10 Å with the following ratio of components in the composition, wt. %: Portland cement - 25-50, sand - 30-60, KAUM water suspension - 0.024-0.64, water - the rest.

The disadvantages of this composition are the difficulty of industrial application, due to the lack of technology for producing carbon-containing material - KAUM in large volumes.

Well-known cementing material (RU patent No. 2151268, published on June 20, 2000), including Portland cement, a carbon-containing additive and calcium or sodium chloride, contains carbon black as a carbon-containing additive in the following ratio of components, wt. %: Portland cement 44-46, carbon black 30-50, calcium or sodium chloride - the rest. The technical result is increasing the sedimentation stability of the solution and obtaining electrically conductive cement stone.

The disadvantage of the known cement material is its low compressive and bending strength.

A cementing composition is known (patent for invention RU No. 2745980, published on 04/05/2021), adopted as a prototype, used for cementing oil and gas wells containing wt. %: Portland cement PCT-I-50 66.0-63.0, water - 33.0-31.0, carbon black - 0.1-5.0, plasticizing additive - the rest. In cementing material, carbon black, carbon black waste, soot, and graphite can be used as a carbon-containing material. The disadvantage of the prototype is the reduced strength of the cement stone at elevated temperatures (75°C) compared to normal temperatures (20°C).

The technical result is to increase the efficiency of well casing under conditions of elevated temperatures.

The technical result is achieved by the fact that it additionally contains silica fume, and as carbon black it contains a mixture of nanoadditives Graphene Oxide “GLC-GO” + Carbon nanotubes CAS 308068-56-6 + High-purity purified nanosilica CAS 112926-00-8 at the following ratio in wt. % by weight of the cement composition 0.1:0.1:0.1, or 0.15:0.1:0.1, or 0.15:0.15:0.1, or 0.15:0, 15:0.15, respectively, with the following ratio of components of the cement composition, wt. %:

Portland cement PCT-I-50 62.1-62.2 water 31.2-31.4 specified mixture of nanoadditives 0.3-0.45 silica smoke 6.0-6.4.

The claimed cement composition for increasing the strength of cement stone for cementing wells includes the following reagents and commercial products containing them:

- Portland cement PCT-I-50 - 62.1-62.2 wt%, produced in accordance with GOST 1581-96;

- water - 31.2-31.4%; produced in accordance with GOST 23732-79;

- nanoadditives - 0.3-0.5%, Graphene Oxide “GLC-GO”, produced according to the specifications “Ningbo Morsh Technology” + Carbon nanotubes, produced according to CAS No. 308068-56-6 + Nanosilica, produced according to CAS No. 112926-00 -8;

- silica smoke - 6.4-5.9%, produced according to CAS No. 69012-64-2.

Portland cement grade PCT-I-50 has a number of advantages, namely widespread availability, high rate of strength gain, early formation of closed porosity, high strength of cement stone, resistance to moderate and elevated temperatures. Portland cement mortars are characterized by rapid setting and rapid hardening, especially at moderate and elevated temperatures.

The water must meet the requirements of technical water and not contain mechanical impurities.

Graphene oxide is an important derivative of the graphene material and can be considered as a layer of graphene with attached oxygen-containing functional groups. Its properties and structure are similar to graphene. Common methods for preparing graphene oxide include the Brodie method, the Staudenmaier method, and the Hummers method. Compared with graphene, grafting oxygen-containing functional groups can reduce the van der Waals interaction between graphene oxide layers and enhance the hydrophilicity of graphene oxide sheets. In addition, oxygen-containing functional groups can participate in chemical or physical interactions, providing a large number of active sites for the binding of other functional groups and organic molecules. Due to these advantages, graphene oxide is also one of the key research areas for cement-based nanomodification.

Carbon nanotubes CAS No. 308068-56-6 offer several advantages as cement reinforcement materials compared to more traditional fibers. First, they have significantly greater strength than conventional fibers, which should improve overall mechanical behavior. Second, they have higher aspect ratios, requiring significantly greater energies to propagate cracks than lower aspect ratio fibers. Thirdly, carbon nanotubes have smaller diameters, which means that if they are distributed evenly according to the invention, they can be widely distributed in the cement matrix with reduced fiber spacing. It should be noted that the nanotubes used in the composition have a diameter in the range from 5 to 15 nanometers, and a length ranging from 10 to 20 nanometers. To achieve good composite reinforcement, it is critical to have a uniform distribution of carbon nanotubes in the matrix.

Nanosilica nanoparticle silica can be defined as nanosilica with a particle size less than or equal to about 100 nm. For example, silica nanoparticles may have a size ranging from about 1 to about 100 nm, from about 1 x 10 ^-9 to about 100 x 10 ^-9 m. In certain exemplary embodiments, the silica nanoparticles may have a size less than or equal to about 50 nm.

For example, compared to incorporating colloidal silica or larger silica particles into a cement mortar, incorporating nanosilica particles into a cement mortar can provide improvements in mechanical properties such as compressive strength, tensile strength, Young's modulus, and Poisson's ratio.

In exemplary embodiments, silica nanoparticles may be present in the cement composition in an amount ranging from about 1 to about 25 weight percent. %.

Silica fume, also known as silica fume, is a by-product of the production of silicon and ferrosilicon alloys. It is a fine powder consisting of spherical particles with a diameter of 0.1 to 1.0 microns, which involves the reduction of silica in a high temperature electric arc furnace. The evaporated silica is collected and cooled to form silica fume. Silica fume is a pozzolanic material, which means it reacts with calcium hydroxide in the presence of water to form calcium silicate hydrate, the main binder in concrete. Due to its high pozzolanic activity and fineness, it has a large specific surface area of 15 to 30 m ² /g, high pozzolanic activity, and a low pH of less than 1.0. It is primarily used in concrete as a pozzolan to improve its strength, durability, and resistance to chemical attack. It also reduces fluid loss and sedimentation instability in cement slurry, increases its cohesion and viscosity.

Example 1. Basic composition (without nanoadditives). The cement mixture is prepared as follows. Obtaining a dispersed mixture by mixing water and silica fume in an ultrasonic bath. The dispersed mixture of water and silica fume is then mixed with the cement in the following order: the dispersed mixture of water and silica fume is added to the cement, or the cement is added to the mixture and held for 30 seconds to absorb the water. Then mix at low speed from 135 to 145 rpm for 30 seconds, after which mixing is stopped and any dough that may have collected on the sides of the bowl in the batch is scraped down for 15 seconds. Mixing is then continued for 60 seconds at an average speed of 275 to 295 rpm.

The resulting cement paste, after mixing, is poured into molds to determine the tensile strength of the stone MPa at uniaxial pressure and kept at a temperature of 20°C for 1.7 days, as well as at a temperature of 160°C in a steam bath for 1.7 days. the purpose of measuring the maximum strength of cement stone in uniaxial compression MPa.

The prepared cement mortar has a density of 1.93 g/cm ³ .

Examples 2-16. To prepare a solution of the proposed mixture, table 1, compositions 2-16. First of all, you need to mix water with silica smoke and nanoadditives for 15-30 seconds. Next, the cement slurry is prepared by adding cement at a water-cement ratio of 0.5. According to ASTM 305 protocol, the mixture is added to the cement or the cement is added to the mixture and held for 30 seconds to absorb water.

Then mix at low speed from 135 to 145 rpm for 30 seconds, after which mixing is stopped and any dough that may have collected on the sides of the bowl in the batch is scraped down for 15 seconds. Mixing is then continued for 60 seconds at an average speed of 275 to 295 rpm.

The resulting cement paste, after mixing, is poured into molds to determine the tensile strength of the stone MPa at uniaxial pressure and kept at a temperature of 20°C for 1.7 days, as well as at a temperature of 160°C in a steam bath for 1.7 days. the purpose of measuring the maximum strength of cement stone in uniaxial compression MPa.

The prepared cement mortar has a density of 1.93 g/cm ³ .

The compositions and structural-rheological results of the proposed cement mixture are given in Table 1. The obtained results of strength tests are given in Table 2.

Table 1 - Concentrations of nanoadditives used in the cement mixture, % wt. No. Composition, wt. % PCT-I- 50 silica smoke Water Nano additives Nanotubes Graphene oxide Nano silica 1 2 3 4 5 6 7 1 61.30 8.0 30.7 0 0 0 2 61.55 7.6 30.8 0.05 0 0 3 61.60 7.4 30.9 0.05 0.05 0 4 61.75 7.2 30.9 0.05 0.05 0.05 5 61.70 7.2 30.9 0.1 0.05 0.05 6 61.85 6.8 31.1 0.1 0.1 0.05 7 62.10 6.4 31.2 0.1 0.1 0.1 8 62.15 6.3 31.2 0.15 0.1 0.1 9 62.20 6.1 31.3 0.15 0.15 0.1 10 62.15 6.1 31.3 0.15 0.15 0.15 eleven 62.20 5.9 31.4 0.2 0.15 0.15 12 62.45 5.5 31.5 0.2 0.2 0.15 13 62.40 5.5 31.5 0.2 0.2 0.2 14 62.65 5.1 31.6 0.25 0.2 0.2 15 62.60 5.1 31.6 0.25 0.25 0.2 16 62.75 4.7 31.8 0.25 0.25 0.25

Example 2. Silica smoke in an amount of 7.6 wt. % is mixed with nanoadditives 0.05 wt.% (Nanotubes 0.05%; Graphene Oxide 0.0%; Nanosilica 0.0%) and water 30.8 wt.%. Portland cement grade PCT-I-50 is added to the solution in an amount of 61.55 wt. %. The resulting composition is thoroughly mixed until a homogeneous mass is obtained. The solution is prepared in the same way as in example 1.

Example 3. Silica smoke in an amount of 7.4 wt. % mixed with nanoadditives 0.1 wt. % (Nanotubes 0.05%; Graphene Oxide 0.05%; Nanosilica 0.0%) and water 7.4 wt. %. Portland cement grade PCT-I-50 is added to the solution in an amount of 61.60 wt. %. The resulting composition is thoroughly mixed until a homogeneous mass is obtained. The solution is prepared in the same way as in example 1.

Example 4. Silica smoke in an amount of 7.2 wt. % mixed with nanoadditives 0.15 wt. % (Nanotubes 0.05%; Graphene Oxide 0.05%; Nanosilica 0.05%) and water 30.9 wt. %. Portland cement grade PCT-I-50 is added to the solution in an amount of 61.75 wt. %. The resulting composition is thoroughly mixed until a homogeneous mass is obtained. The solution is prepared in the same way as in example 1.

Example 5. Silica smoke in an amount of 7.2 wt. % mixed with nanoadditives 0.2 wt. % (Nanotubes 0.1%; Graphene Oxide 0.05%; Nanosilica 0.05%) and water 30.9 wt. %. Portland cement grade PCT-I-50 is added to the solution in an amount of 61.70 wt. %. The resulting composition is thoroughly mixed until a homogeneous mass is obtained. The solution is prepared in the same way as in example 1.

Examples 2 to 5 are not considered the claimed cement composition, since they do not provide the required degree of increase in strength.

Example 6. silica smoke in an amount of 6.8 wt. % mixed with nanoadditives 0.25 wt. % (Nanotubes 0.1%; Graphene Oxide 0.1%; Nanosilica 0.05%) and water 31.1 wt. %. Portland cement grade PCT-I-50 is added to the solution in an amount of 61.85 wt. %. The resulting composition is thoroughly mixed until a homogeneous mass is obtained. The solution is prepared in the same way as in example 1. The uniaxial compressive strength of cement stone at a temperature of 20°C was 14.8 MPa and 33.2 MPa after 1 and 7 days, respectively, and at a temperature of 160°C it was 40 MPa and 43 MPa after 1 day and 7 days respectively.

Example 7. Silica smoke in an amount of 6.4 wt. % mixed with nanoadditives 0.3 wt. % (Nanotubes 0.1%; Graphene Oxide 0.1%; Nanosilica 0.1%) and water 31.2 wt. %. Portland cement grade PCT-I-50 is added to the solution in an amount of 62.1 wt. %. The resulting composition is thoroughly mixed until a homogeneous mass is obtained. The solution is prepared in the same way as in example 1. The cement composition is considered declared, since the uniaxial compressive strength of cement stone at a temperature of 20°C was 15.5 MPa and 35.1 MPa after 1 and 7 days, respectively, and at a temperature of 160°C was 41.1 MPa and 44.2 MPa after 1 day and 7 days, respectively.

Example 8. Silica smoke in an amount of 6.3 wt. % mixed with nanoadditives 0.35 wt. % (Nanotubes 0.15%; Graphene Oxide 0.1%; Nanosilica 0.1%) and water 31.2 wt. %. Portland cement grade PCT-I-50 is added to the solution in an amount of 62.15 wt. %. The resulting composition is thoroughly mixed until a homogeneous mass is obtained. The solution is prepared in the same way as in example 1. The cement composition is considered declared, since the uniaxial compressive strength of cement stone at a temperature of 20°C was 16.3 MPa and 35.9 MPa after 1 and 7 days, respectively, and at a temperature of 160°C was 42.3 MPa and 45.5 MPa after 1 day and 7 days, respectively.

Example 9. Silica smoke in an amount of 6.1 wt. % mixed with nanoadditives 0.4 wt. % (Nanotubes 0.15%; Graphene Oxide 0.15%; Nanosilica 0.1%) and water 31.3 wt. %. Portland cement grade PCT-I-50 is added to the solution in an amount of 62.20 wt. %. The resulting composition is thoroughly mixed until a homogeneous mass is obtained. The solution is prepared in the same way as in example 1. The cement composition is considered declared, since the uniaxial compressive strength of cement stone at a temperature of 20°C was 17.8 MPa and 36.6 MPa after 1 and 7 days, respectively, and at a temperature of 160°C was 43.8 MPa and 46.9 MPa after 1 day and 7 days, respectively.

Example 10. Silica smoke in an amount of 6.1 wt. % mixed with nanoadditives 0.45 wt. % (Nanotubes 0.15%; Graphene Oxide 0.15%; Nanosilica 0.15%) and water 31.3 wt.%. Portland cement grade PCT-I-50 is added to the solution in an amount of 62.15 wt. %. The resulting composition is thoroughly mixed until a homogeneous mass is obtained. The solution is prepared in the same way as in example 1. The cement composition is considered declared, since the uniaxial compressive strength of cement stone at a temperature of 20°C was 18.3 MPa and 37.4 MPa after 1 and 7 days, respectively, and at a temperature of 160°C was 44.1 MPa and 47.8 MPa after 1 day and 7 days, respectively.

Example 11. Silica smoke in an amount of 5.9 wt. % mixed with nanoadditives 0.5 wt. % (Nanotubes 0.2%; Graphene Oxide 0.15%; Nano Silica 0.15%) and water 31.4 wt. %. Portland cement grade PCT-I-50 is added to the solution in an amount of 62.20 wt. %. The resulting composition is thoroughly mixed until a homogeneous mass is obtained. The solution is prepared in the same way as in example 1.

Example 12. Silica smoke in an amount of 5.5 wt. % mixed with nanoadditives 0.55 wt. % (Nanotubes 0.2%; Graphene Oxide 0.2%; Nanosilica 0.15%) and water 31.5 wt. %. Portland cement grade PCT-I-50 is added to the solution in an amount of 62.45 wt. %. The resulting composition is thoroughly mixed until a homogeneous mass is obtained. The solution is prepared in the same way as in example 1.

Example 13. Silica smoke in an amount of 5.5 wt. % mixed with nanoadditives 0.6 wt. % (Nanotubes 0.2%; Graphene Oxide 0.2%; Nanosilica 0.2%) and water 31.5 wt. %. Portland cement grade PCT-I-50 is added to the solution in an amount of 62.40 wt. %. The resulting composition is thoroughly mixed until a homogeneous mass is obtained. The solution is prepared in the same way as in example 1.

Example 14. Silica smoke in an amount of 5.1 wt. % mixed with nanoadditives 0.65 wt. % (Nanotubes 0.25%; Graphene Oxide 0.2%; Nanosilica 0.2%) and water 31.6 wt. %. Portland cement grade PCT-I-50 is added to the solution in an amount of 62.65 wt. %. The resulting composition is thoroughly mixed until a homogeneous mass is obtained. The solution is prepared in the same way as in example 1.

Example 15. Silica smoke in an amount of 5.1 wt. % mixed with nanoadditives 0.7 wt. % “Nanotubes 0.25%; Graphene oxide 0.25%; Nanosilica 0.2%" and water 31.6 wt. %. Portland cement grade PCT-I-50 is added to the solution in an amount of 62.60 wt. %. The resulting composition is thoroughly mixed until a homogeneous mass is obtained. The solution is prepared in the same way as in example 1.

Example 16. silica smoke in an amount of 4.7 wt. % mixed with nanoadditives 0.75 wt. % (Nanotubes 0.25%; Graphene Oxide 0.25%; Nano Silica 0.25%) and water 31.8 wt. %. Portland cement grade PCT-I-50 is added to the solution in an amount of 62.75 wt. %. The resulting composition is thoroughly mixed until a homogeneous mass is obtained. The solution is prepared in the same way as in example 1.

Examples 11 to 16 are not considered the claimed cement composition, since they do not provide the required degree of increase in strength.

The composition of the composition and strength characteristics are given in tables 1 and 2. Thus, examples 7 to 10 represent the composition of the inventive cement.

The use of the proposed cement slurry will expand the scope of application of the cement mixture and ensure long-term reliable fastening of casing strings at normal, moderate and elevated temperatures and increase the strength of the adhesive adhesion of the cement mixture to rock and casing.

Table 2 - results of strength tests. No. Ultimate uniaxial compressive strength of cement stone, MPa 20°C 160°C 1 day 7 days 1 day 7 days 1 11.4 25.3 22.8 24.4 2 12.3 26.4 34.7 36.2 3 13.6 28.7 36.8 38.5 4 13.87 30.8 37.7 40.1 5 14.2 32.3 38.4 41.2 6 14.8 33.2 40 43 7 15.5 35.1 41.1 44.2 8 16.3 35.9 42.3 45.5 9 17.8 36.6 43.8 46.9 10 18.3 37.4 44.1 47.8 eleven 9.8 22.7 21.1 21.8 12 10.8 24.5 22.2 23.3 13 7.5 19.5 18.9 19.9 14 7.1 17.2 18.5 19 15 7 17 18 18.9 16 7 17 17.8 18.3

From Table 2, we note that samples 7 to 10 achieve a clear improvement, therefore, the cement mixture will improve the thread quality of cement casing pipes and the durability of wells at normal, medium and high temperatures.

Claims (2)

Backfilling composition, including Portland cement PCT-I-50, water and carbon black, characterized in that it additionally contains silica fume, and as carbon black it contains a mixture of nanoadditives Graphene oxide “GLC-GO” + Carbon nanotubes CAS 308068-56-6 + Nanosilica OSCH CAS 112926-00-8 at the following ratio in wt.% of the cement composition: 0.1:0.1:0.1, or 0.15:0.1:0.1, or 0.15:0 ,15:0.1, or 0.15:0.15:0.15, respectively, with the following ratio of components of the cement composition, wt.%: Portland cement PCT-I-50 62.1-62.2 water 31.2-31.4 specified mixture of nanoadditives 0.3-0.45 silica smoke 6.0-6.4