RU2078906C1 - Grouting mortar - Google Patents

Abstract

FIELD: well construction; applicable in preparation of plunging materials for cementing oil, gas and other wells. SUBSTANCE: grouting mortar contains, mas.p.p.: portland cement 100; aluminium powder 0.3-0.5 anionic surfactant - reagent ML-72 - mixture of sodium alkyl sulfonate and sodium alkyl benzenesulfonate and polyglycol ether of di-tert-butylphenol 0.15-0.025; nonionic surfactant - regent HG-12 - hydroxyethylated isopropyl phenol based on trimer propylene 0.015-0.025; plasticizer - nitrilotrimenthylphosphonic acid 0.02-0.05 and water 50. EFFECT: higher efficiency. 1 tbl

Description

 The invention relates to the construction of wells, namely, cementing materials intended for cementing oil, gas and other wells.

 When cementing wells, under-grouting to the design level is observed due to its absorption by cracks in loose and porous rocks, as well as as a result of hydraulic fracturing.

 To isolate the absorption zones of the solution during its completion into the well, grouting mortar is known, including Portland cement, clogging additive and water.

 The disadvantage of this solution is the increased water demand due to poor pumpability, the need to introduce an additive of a certain size into the solution, depending on the width and type of cracks in the rock. Usually, lightweight solutions with reduced strength characteristics of hardened stone with high water and gas permeability, with low adhesion to the pipe are created to seal the cracks. Such plugging additives are unsuitable for separation of formations, especially in the area of the reservoir.

 A well-known grouting solution for isolating the absorption zones in the well, including Portland cement, a gas additive and water of the following composition, wt.

Portland cement 64.6
Liquid glass 1.55
Sodium Chloride 1.29
Aluminum Powder 0.13
Water Else
Gas evolution is accompanied by a sharp loss of solution mobility. Volume growth and loss of mobility while this solution is in the absorbing horizon will be the main properties that ensure isolation of the absorption zones.

 The disadvantage is that the known solution is used for shallow wells with a low temperature and pressure. Such a solution is unsuitable for isolating absorption zones in the zone of separation of formations with high temperature and pressure, since it contains an insufficient amount of aluminum powder, as a result of which the known solution does not expand.

 The closest technical solution, taken as a prototype, is a method of cementing wells, including the injection of cement slurry containing Portland cement, aluminum hydrophobized powder and water. Positive in the known method is that the solution contains an increased amount of aluminum up to 0.5% or more by weight of cement, which allows using it to create the expansion of the absorbed solution in cracks at high pressure in the absorption zone. In addition, the known solution reduces the likelihood of hydraulic fracturing in the zone of separation of the layers near the reservoir due to overcooling of the walls of the well during cementing with conventional Portland cement hot wells.

 A disadvantage of the known solution is that a lot of the solution can be absorbed before the manifestation of the insulating effect. In addition, a gas phase in a microgas state is not created in such a solution, which allows the gas to diffuse from the solution. Such a solution is unstabilized.

 The purpose of the invention is to improve the quality of isolation of absorption zones in deep wells while increasing strength and adhesion, water filtration resistance of cement stone due to increased adhesion to enclosing surfaces and creating an expanding-stress state in the solution and stone.

 The goal is achieved by the fact that in a known solution containing Portland cement, aluminum powder and water, an additional fish scale plugging additive ⌀ 5-20 mm plasticizer-diluent nitrilotrimethylphosphonic acid (NTF), non-ionic surfactant (nonionic surfactant) -HG-12 company " Buna "made in Germany and anionic surfactant (APAW) -ML-72 based on mixtures of synthetic surfactants in the following ratio, wt.h.

Portland cement 100
Fish scales 1 4
Aluminum powder 0.3 0.5
Plasticizer 0.03 0.05
Nonionic surfactants 0.015 0.025
AAPA 0.015 0.025
Water 50
New in the proposed grouting mortar is that it contains fish scales, parts by weight, as a plugging filler. 1 4, which is most effective for plugging cracks, creating an impenetrable shell around the cracks, which increases the insulating properties of aluminum powder at parts by weight 0.3 0.5 and the quantitative ratio of the components.

Fish scales ⌀ 5-20 mm refers to the type of plate-shaped plugging fillers and is effective for plugging cracks located parallel to the wellbore. Part of the scales goes into the crack, part, perpendicular to the penetration of cracks into the rock, forms a shell and reliably prevents further absorption of the cement mortar by the crack, which contributes to good isolation of the absorption zone in loose porous rocks and in the case of hydraulic fracturing. Scales have high tensile strength, this gives it a reinforcing character in a cement stone. The scales have a low density of 0.6 0.7 g / cm ³ and slightly changes the density of the cement slurry; the scales have no pores and do not absorb water, but adsorb it by the surface. To increase the adhesion of the scales to the cement stone (matrix), it is necessary to remove the mucous membrane from the surface of the scales. This is achieved by washing it with water, but preferably in a 5% solution of soda ash (Na ₂ CO ₃ ) at a temperature of 50-60 ^o C for 15 to 20 minutes. After washing, the solution is drained, the scales are dried under natural conditions. Part of the soda remains on the surface of the scale as a result of chemisorption, which further increases its adhesion to the stone and increases the effect of reinforcing it. The introduction of scales into the binder increases the physicomechanical parameters of the stone being formed: mechanical strength, adhesion to enclosing surfaces, water filtration resistance in the pipe-stone-well wall system, as well as inside the fracture.

 In a cement mortar containing aluminum powder PAP -1, produced in accordance with GOST 5494-71, a microgas phase is generated, which, due to its small diameter, can be expelled from the solution by the force of expulsion of this solution or even diffuse through the hardened stone. To prevent this, a gas-saturated cement mortar containing PAP-1 aluminum powder must be stabilized. To stabilize the solution and the resulting microgas phase, an effective anionic surfactant, ML-72, based on mixtures of synthetic surfactants: TU 84-348-73, is introduced into the solution during its preparation. A microgas bubble with an adsorbed film of ML-72 forms an aggregate of much larger diameter compared to a gas bubble, and this prevents it from diffusing through the solution and hardened stone, which helps to maintain pore pressure in it for a long time.

 To impart hydrophilicity to hydrophobic aluminum powder during the preparation of an aluminum suspension, a nonionic surface-active substance (nonionic surfactant) -HG-12 from Buna from Germany is introduced into the suspension water. The disadvantage of scales is that it creates additional hydraulic friction resistance with its surface. This affects the pumpability of the cement slurry, especially containing aluminum powder, generating a gas phase. To improve the pumpability of a cement mortar containing aluminum and scales, an effective plasticizer NTF manufactured according to TU 6-02-11-72 -79 is introduced into the mixing water.

Studies to determine the parameters and the optimal composition were carried out according to GOST 1581-85, GOST 26798.0 -85, GOST 26798.2-85. The physical parameters of the solutions and the strength characteristics of the hardened stone of daily hardening were determined at a temperature of 75 ^o C and a pressure of 30 MPa. Based on cement-based Portland cement PCT 20 50 manufactured by the Sukholozhskcement Production Association, solutions of different compositions were prepared and parameters determined using standard equipment. Strength characteristics were determined at PCC-1, the relative deformability characteristic was calculated as the ratio of compressive strength to bending. The adhesion of stone to metal was determined in a pipe with an inner diameter of 50 mm. Sample height 50 mm. The resistance of water filtration was determined on a special stand simulating approximate conditions in the well; adhesion to metal was also determined on this stand. The results are shown in the table. As can be seen from the table, the thickening of the solution containing aluminum powder is reduced in time in relation to pure Portland cement by half. Thickening and other characteristics of pure cement are not shown in the table. For a pure solution, thickening averages 2 hours and 40 minutes for the accepted conditions. The introduction of fish scales in a solution containing aluminum powder further reduces the thickening time and the ability to pump the solution into the well. The production requirements should have a pumping time of at least 50 minutes to deliver the solution to the zone of separation of the layers of likely hydraulic fracturing in them.

 The pumpability time of the solution was taken as the basis when choosing the composition of the studied solutions.

From the table (examples 3 to 5) it is seen that the scales washed with water give a stone with low strength characteristics due to poor removal of mucus from the surface of the scales than washed with a solution of soda ash at a temperature of 60 ^o C. For a scale treated with soda, more adhesion to the contact surface in the stone, hence the high strength, adhesion to metal and water filtration resistance. With an increase in the amount of scales in the stone, these indicators increase slightly. Only with the introduction of scales in a solution containing aluminum powder more wt.h. 0.2, the adhesion of the stone to the metal and the resistance to water filtration sharply increase (examples 6–11), the more aluminum powder and scales in the solution, the higher these indicators. The solution containing aluminum wt.h. 0.6 even when the content of the scales wt.h. 3 is poorly pumped, despite the fact that NTF is contained in the solution by weight 0.6.

 Thus, the introduction of scales wt.h. 1 to 4 in cement grout containing aluminum powder, parts by weight 0.3 0.5, gives good strength characteristics, increases adhesion to metal and increases resistance to water filtration. The content of aluminum powder below wt.h. 0.3 (example 1) does not allow expansion of the solution at a pressure of 30 MPa and somewhat expands with wt.h. 0.3 (examples 2, 6, 10). This indicates that the cement mortar containing aluminum powder with wt.h. 0.3 0.5 and scales with parts by weight 2 4 is a good insulating grouting material both for plugging cracks and for separating formations.

 The content of scales in the solution is determined by the degree of its absorption into the reservoir. The number of scales with wt. Part 1 2 is used for absorbing layers of loose, porous, slightly prone to hydraulic fracturing. With parts by weight 3 4 for isolation of highly absorbed formations, with the possible occurrence of hydraulic fracturing and the formation of deep cracks. The content of the scales above wt.h. 4 affects the pumpability of the solution and slightly affects the strength characteristics of the hardened stone. Lower limit wt.h. 0.3 aluminum powder is determined by the ability to expand at a reservoir pressure of 20 MPa (well depth ≈2000 m), and the upper limit wt.h. 0.5 for a pressure of 30 MPa and above (well depth 3000 m and above). The amount of nonionic surfactants and anionic surfactants depends on the content of aluminum powder in the solution with a surfactant / PAP-1 ratio of 1/20. The limits of the content of the plasticizer NTF are determined by the thickening time of the solution and the possibility of pumping it to a given area of the wells, in particular to the isolation and separation zone of the formations. This time will be 50-60 minutes.

Example. Take 1000 g (parts by weight of 100) of grouting portland cement PTsT-D20-50 PO Sukholozhskcement, 40 g (parts by weight of 4.0) of dry fish scales, previously washed in a 5% soda solution, are introduced into it ( Na ₂ CO ₃ ) at a temperature of 60 ^o C for 15 to 20 minutes and dried. The mixture is stirred manually. Separately, an aluminum suspension and a mixing liquid are prepared. The suspension with a volume of 100 cm ³ contains aluminum powder with wt.h. 0.4 in an amount of 4 g, nonionic surfactant with parts by weight 0.02 in an amount of 0.2 g. The mixing liquid contains water with parts by weight of 50, taking into account the water spent on the preparation of the suspension (W / C 0.5), in an amount of 400 g, an anionic surfactant with wt.h. 0.02 in the amount of 0.2 g, for the formation of the microgas phase and stabilization of the solution, the plasticizer is NTF with wt. h. 0.04 in the amount of 0.4 g. The scaly-cement mixture is closed on a mixing liquid, while pouring a suspension into it. The solution is mixed in a laboratory mixer, poured into molds and into a cylindrical chamber with an internal ⌀ -50 mm device on a bench simulating approximate conditions in the well in the zone of separation of the layers. Forms are placed in PCC-1. Hardening conditions: time 24 hours, temperature 75 ^o C, pressure 30 MPa. The strength of the samples and the relative deformability characteristic with respect to the ratio of compressive strength to bending, the adhesion of the stone to the pipe, and the water filtration resistance, which is equal to the pressure at which it begins to decrease during the migration of water through the stone-pipe system, are determined. The results are shown in the table (experiment No. 8).

 The technology for preparing the proposed solution is as follows. Knowing the volume of the solution and the geological and technical conditions in the well, the number of components is calculated. When overstocking the mixing machine SM-20 for a certain amount of cement, for example 4 bags (50 kg each) wt.h. 100 add 8 kg of scales (parts by weight of 4). The mixture is then mixed twice using a second mixer. In the capacity of the cementing unit SM-320A, a suspension of aluminum powder is prepared, and in another a mixing fluid. When cementing the absorption zone, a cement-flake mixture, suspension and mixing liquid are simultaneously fed into the mixing tray, and the closed solution is pushed to the required level in the well.

 The positive effect will be determined by the amount of consumed solution (cement), the time between repair and correction work and the quality of cementing wells.

Claims (1)

 A cement slurry comprising Portland cement, aluminum powder and water, characterized in that it additionally contains fish scales, anionic surfactant reagent ML-72, a mixture of alkyl sulfonate, sodium alkyl benzene sulfonate and di-tert-butyl phenol polyglycol ether, a nonionic surfactant reagent HG-12 - ethoxylated isopropylphenol based on propylene trimers and a plasticizer nitrilotrimethylphosphonic acid in the following ratio of components, wt. h Portland cement 100
Aluminum powder 0.3 0.5
Fish scales 1 4
Reagent ML-72 0.015 0.025
Reagent HG-12 0.015 0.025
Nitrilotrimethylphosphonic acid 0.03 0.05
Water 50s

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