RU2530153C2 - Grouting composition for cementing low-pressure well - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to oil and gas well casing. The grouting composition for cementing a low-pressure well includes 60.5-63.7 wt % portland cement, 0.61-1.53 wt % aluminium salt. The composition further includes 0.003-0.045 wt % oxyethylated alkylphenols 3-AI, 0.61-1.3 wt % carbonates, which are in the form of potassium or sodium carbonate, and water.

EFFECT: low density of the grouting mortar and improved sedimentation stability thereof.

1 tbl, 7 ex

Description

The invention relates to the field of construction of oil and gas wells and is used for fastening a wellbore drilled in mining and geological conditions with low reservoir pressure. Such compositions are necessary to prevent fracturing, absorption of cement mortar, preventing loss of circulation of the mortar and the occurrence of an emergency.

In the literature [G.N. Pervushin, D.V. Oreshkin “Formation of the structure of cement stone with glass microspheres in the conditions of the well” // Construction of oil and gas wells on land and at sea - 2005. - No. 11. - With 34-38] known the composition of ultralight cement slurry intended for cementing the annulus of a well with low reservoir pressure. The disadvantage of this solution is that in order to achieve the necessary technological parameters (spreadability, solution density) it is necessary to use a high water content, which significantly increases the sedimentation instability of the cement slurry and its filtrate recovery, and the resulting stone has a reduced strength and shrinkage.

The closest to the claimed object in composition is the grouting composition [V.E. Akhrimenko, Z.M. Ahrimenko. Patent No. 2425956. E21B 33/13], designed for cementing low-temperature wells. The disadvantage of this solution is the high density of the cement slurry, which is unacceptable when cementing wells with low reservoir pressure due to the risk of fracturing and the occurrence of cement slurry absorption.

The technical result is a decrease in the density of cement slurry, an increase in its sedimentation stability and a reduction in the setting time.

The technical result is achieved in that the grouting composition for cementing wells with low reservoir pressure based on Portland cement and a mixing fluid, including water and an aluminum salt, characterized in that it additionally contains ethoxylated 3-AI alkyl phenols and carbonates, which are used as potassium carbonates or sodium, in the following ratio, wt.%

Portland cement 60.5-63.7 Aluminum salt 0.61-1.53 Oxyethylated 3-AI alkyl phenols 0.003-0.045 Potassium or sodium carbonate 0.61-1.3 Water Rest

The novelty of the proposed solution lies in the fact that among all the studied salts introduced into the cement mortar in different proportions with aluminum salts, the effect of the greatest decrease in the density of the mortar and increase in its sedimentation stability is observed in the case of salts of carbonic acid (potassium or sodium carbonates). These salts are a source of carbonate anions, which form instantly hydrolyzable aluminum carbonate with aluminum cations. Aluminum salts exchange with potassium or sodium carbonate according to the equation

The resulting aluminum carbonate does not exist in solution, because instantly undergoes hydrolysis according to the equation

The total process of interaction of solutions of aluminum sulfate and sodium carbonate is expressed by the following reaction equation

The evolved gas saturates the cement slurry and reduces its density. In addition, surfactants in the form of ethoxylated alkyl phenols with vigorous stirring of the solution contribute to the additional involvement of air, which makes the solution even easier, and the aluminum hydroxide formed in the solution in the form of a volume gel holds cement particles, prevents delamination of the cement and makes it sedimentation stable.

где n - степень оксиэтилирования 3 и более (Краткая химическая энциклопедия, изд-во «Советская энциклопедия», М., 1961, с.130). Т.к. торговое название пенообразователя связано с его степенью оксиэтилирования, то указанные ПАВ получили рабочее название 3-АИ.Oxyethylated alkyl phenols of the general formula were used as surfactants

where n is the degree of hydroxyethylation of 3 or more (Brief chemical encyclopedia, publishing house "Soviet Encyclopedia", Moscow, 1961, p.130). Because the trade name of the foaming agent is associated with its degree of hydroxyethylation, the specified surfactants received the working name 3-AI.

The author’s theoretical studies on the choice of the main reagents that provide a decrease in the density and increase the sedimentation stability of cement slurries led the author to use salts of highly charged cations, which form, together with carbonates, instantly hydrating salts with the formation of gaseous products and products, leading to a sharp increase in hydrate neoplasms such as calcium hexahydroxoaluminate (Ca ₃ [Al (OH) ₆ ]), which is accompanied by accelerated hardening of the cement mortar.

The novelty of the proposed technical solution lies in the fact that aluminum hydroxide formed during the exchange reactions, due to the highly developed gel surface, keeps the gas-filled cement mortar in suspension, prevents its stratification and stone shrinkage. The remaining unreacted aluminum cations interact with the free lime of the cement slurry, which leads to an increase in the concentration of hydrated neoplasms and accelerate the hardening of the cement slurry. In addition, the salts of nitric, sulfuric and hydrochloric acids formed during the hydrolysis of the reaction are also accelerators of the hardening of cement mortars, which ensures rapid hardening of light cement slurries even at low positive temperatures.

When cementing wells with low reservoir pressure, light quickly hardening cement slurries with low water loss are especially necessary, forming a strong, non-shrinking stone with high adhesion properties during the wet season (expected cement hardening time).

Strength properties of cement stone (compression and bending) were determined by the existing method, and adhesion (shear adhesion) using the device shown in the figure. For this, a metal rod was placed in the cement mortar and left alone. After a certain hardening time, using the specified device, the load applied to the rod by its shift in the cement stone was determined. A grouting mortar is prepared by vigorously mixing a portion of Portland cement with a mixing fluid, consisting of water, aluminum salt, ethoxylated 3-AI alkylphenoids and an alkali metal carbonate.

Since the main ingredients of the composition are aluminum salts, ethoxylated alkyl phenols 3-AI and potassium or sodium carbonates, the following weight ratios are presented in the examples.

Example 1. Prepare a mixing liquid from solutions of aluminum sulfate 2 g (0.64%); 0.1 g (0.003%) of ethoxylated 3-AI alkyl phenols in terms of dry matter, 2 g (0.64%) of K ₂ CO ₃ and water 110 ml (34.8%). The resulting mixing liquid is mixed with 200 g of Portland cement. After thorough mixing with an electric mixer, the technological parameters of the cement mortar, the strength of the stone and its adhesion after 2-day hardening in drinking water at 22 ° C were determined. Spreadability of the resulting solution 19.5 cm; the density of the solution is 1452 kg / m ³ ; start of setting 7 hours 50 minutes; end of setting 11 hours 20 minutes; stone compressive strength of 2.8 MPa; adhesion of 1.7 MPa.

Example 2. Prepare a mixing liquid from solutions of aluminum sulfate 2 g (0.63%); ethoxylated alkyl phenols 3-AI 0.02 g (0.006%); potassium carbonate 2 g (0.63%); water 115 ml (36%). The resulting mixing liquid is mixed with 200 g (63.5%) of Portland cement. After thorough mixing with an electric mixer, the technological parameters of the cement mortar, the strength of the stone and its adhesion after 2-day hardening in drinking water at 22 ° C were determined. Spreadability of the resulting solution 20.5 cm; density 1273 kg / m ³ ; start of setting 8 hours 40 minutes, end of setting 12 hours 15 minutes; stone strength 2.3 MPa; adhesion of 1.4 MPa.

Example 3. Preparing a mixing liquid from solutions of aluminum sulfate 5 g (1.53%), ethoxylated alkyl phenols 3-AI 0.12 g (0.037%); potassium carbonate 3 g (0.9%) and water 120 ml (36.8%). The resulting mixing liquid is mixed with 200 g (61.3%) of Portland cement. After mixing on an electric mixer, the technological parameters of the solution, the strength of the stone and its adhesion after 2-day hardening in drinking water at 22 ° C were determined. Spreadability cavern 21.5 cm; density 532 kg / m ³ , setting time 9 hours 12 minutes, setting hours 14 hours 20 minutes, stone strength 1.6 MPa 4, adhesion 0.85 MPa.

Example 4. Prepare a mixing liquid from solutions of aluminum chloride 2 g (0.63%); hydroxyethylated 3-AI alkyl phenols 0.01 g (0.003%); sodium carbonate 2 g (0.63%), water 110 g (35.1%). The resulting mixing liquid is mixed with 200 g of Portland cement. After stirring with the help of an electric mixer, the technological parameters of the solution, the strength of the stone and its adhesion after 2-day hardening in drinking water at 22 ° C were determined. The spreadability of the resulting solution is 19.5 cm, the density is 1448 kg / m ³ , the beginning of setting 7 hours 30 minutes, the end of setting 10 hours 20 minutes; stone strength 2.7 MPa; adhesion of 1.6 MPa.

Example 5. Prepare a mixing liquid from solutions of aluminum chloride 2 g (0.61%); ethoxylated alkyl phenols 3-AI 0.12 g (0.037%); sodium carbonate 2 g (0.61%); water 120 ml (37%). The resulting mixing liquid is mixed with 200 g (61.3%) of Portland cement. After mixing on an electric mixer, the technological parameters of the solution, the strength of the stone and its adhesion after 2-day hardening in drinking water at 22 ° C were determined. Spreadability of the resulting solution 20 cm; density 768 kg / m ³ ; setting time 8 hours 40 minutes; end of setting 13 hours 35 minutes, stone strength 1.7 MPa; adhesion of 0.98 MPa.

Example 6. Prepare a mixing liquid from solutions of aluminum chloride 1 g (0.31%); ethoxylated alkyl phenols 3-AI 0.12 g (0.037%); sodium carbonate 2 g (0.62%); water 120 ml (37%). The resulting mixing liquid is mixed with 200 g (61.9%) of Portland cement. After mixing on an electric mixer, the technological parameters of the solution were determined; spreadability 22.5 cm; density 786 kg / m ³ ; the system is stratified. Due to the instability of the system, other parameters were not determined.

Example 7. Prepare a mixing liquid from solutions of aluminum chloride 4.5 g (1.3%); hydroxyethylated 3-AI alkyl phenols 0.12 g (0.013%); sodium carbonate 4.5 g (1.3%), water 120 ml (36.5%). The resulting mixing liquid is mixed with 200 g (60.8%) of Portland cement. After mixing, the solution turned out to be very viscous with a density of 624 kg / m ³ , therefore, the remaining parameters were not determined.

All the data given in examples 1-7 are presented in the table "The influence of reagents on the properties of cement mortar and stone."

Claims (1)

Grouting composition for cementing wells with low reservoir pressure based on Portland cement and a mixing fluid, including water and aluminum salt, characterized in that it additionally contains ethoxylated 3-AI alkyl phenols, and carbonates, which use potassium or sodium carbonates, in the following ratio components, wt.%
Portland cement 60.5-63.7 Aluminum salt 0.61-1.53 Oxyethylated 3-AI alkyl phenols 0.003-0.045 Potassium or sodium carbonate 0.61-1.3 Water Rest