CS201438B1 - Antifiltration additive for cement wells for deep drilling - Google Patents

Abstract

Anti-filtration additive for cement tamponage mixture, intended especially for filling the space between casings and walls of a deep well, in which the temperature is elevated. The purpose of the invention is to increase the anti-filtration effect of the additive even at temperatures above 100 °C and to limit foaming and thickening of the cement tamponage mixture. The anti-filtration additive consists of a water-soluble cellulose derivative with an average degree of polymerization higher than 200, formed by the action of alkylene oxides on alkali cellulose and a polycondensate of formaldehyde with alkyl polyphenols sulfonated in the alkyl chain. The weight ratio of both components is in the range of 1:0.5 to 1:12. The addition of a polycondensate of formaldehyde with naphthalenesulfonic acid in a weight ratio of 1:0.1 to 1:1 is preferred. The invention is applicable in the field of deep drilling for oil and natural gas, in mining for sealing mine workings and in construction for insulating building foundations.

Description

Antifiltration additive for cement wells for deep drilling

Antifiltration additive for cementitious tamponage mixture, designed especially for filling the space between the casing and the well borehole walls in which the temperature is elevated. The purpose of the invention is to increase the antifiltration effect of the additive even at temperatures above 100 ° C and to reduce foaming and thickening of the cementitious tampon. The antifiltration additive consists of a water-soluble cellulose derivative having an average polymerization degree of more than 200 resulting from the action of alkylene oxides on alkali cellulose and a polycondensate of formaldehyde with alkyl polyphenols sulfonated in the alkyl chain. The weight ratio of both components is in the range of 1: 0.5 to 1: 12. Preference is given to adding polycondensate of formaldehyde with naphthalenesulfoacids in a weight ratio of 1: 0.1 to 1: 1. The invention is applicable in the field of deep drilling for oil and gas, in the mining industry to seal mines and in the construction industry to insulate the foundations of buildings.

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SUMMARY OF THE INVENTION The present invention is directed to an antifiltration additive for a cementitious tamponizer composition, especially for filling the space between the casing and the well borehole walls in which the temperature is elevated.

The space between the casing and the borehole walls is usually filled with a water-based tamponage mixture and any mineral filler additives. The tampon suspension is pumped by casing at the beginning of the well, where its flow turns upwards and gradually fills the casing annular space. If the deep well passes through the porous geological layers, the liquid phase of the tamponage mixture is filtered into the porous layers, the mixture thickens, ethane is inexhaustible and the tamponage ends in an accident.

To prevent filtering of the liquid phase, antifiltration additives having the ability to retain the liquid phase, the mixing water, in suspension and reduce filtration of the suspension are added to the cementitious tamponage composition. Water-soluble organic polymers or aqueous suspensions of hydrophilic organic polymers, in particular cellulose derivatives, polyvinyl alcohol, polyacrylamide and its hydrolysates, starches, gelatin, latexes and the like have been used as antifiltration additives for cementitious tampon mixtures.

A disadvantage of the antifiltration additives known and used up to now is that at a concentration which is optimum in terms of antifiltration effect, they thicken the cementitious tamponant mixture, reduce its pumping speed and thus place considerable demands on the performance of the pumping aggregates. With the high concentration of known antifiltration additives, there are also negative side effects, such as excessive foaming of the mixture and a reduction in the strength of the resulting cement stone.

Plasticizers are applied to the mixture to eliminate excessive thickening of the cementitious tamponage composition by the known antifiltration additives. When, for example, hydroxyethyl cellulose, alkyl cellulose, polyethylene glycol cellulose and other water-soluble cellulose derivatives are used as antifiltration additives, plasticizers such as formaldehyde condensates and naphthalenesulfoacids in the form of sodium, potassium or lithium salts are added. Said combinations of water-soluble cellulose derivatives with naphthalene sulfoacid condensates are the essence of known commercial antifiltration additives. Their drawback is that they are effective only at relatively low temperatures. As the temperature rises, their antifiltration effect decreases rapidly and this decrease cannot be eliminated even by increasing the concentration of antifiltration additives.

For the tamponage of deep earth wells in which the temperature is above 100 ^° C, the known antifiltration additives are not effectively applicable.

The above-mentioned disadvantages are eliminated by the antifiltration additive to the cementitious tamponizing composition according to the invention, which consists in that the antifiltration additive consists of a water-soluble cellulose derivative with an average polymerization degree higher than 200 resulting from alkylene oxides alkyl chain, the weight ratio of both components being in the range of 1 to 0.5 to 1 s 12.

A further reduction in filterability of the cementitious tamponage composition is achieved when the anti201438 filter additive comprises polycondensate of formaldehyde and naphthalenaulfoacids, in weight ratio to the polycondensate of formaldehyde with alkylphenols sulfonated in the alkyl chain of 1: 0.1 to 1 and 1.

The advantage of the antifiltration additive according to the invention is its efficiency even at temperatures above 100 ^° C. It makes it possible to assemble tampon mixtures based on cement or cement and mineral fillers such as silica flour, ground sand, slag and diatomite. It does not prevent the application of other additives, especially plasticizers and retardants. Compared to the use of hydroxyethyl cellulose or polyethylene glycol cellulose alone, the additive according to the invention has a greater anti-filtration effect and the tampon mix is more fluid, which is advantageous especially in tamponage with a turbulent flow regime. In comparison with conventional applications and hydroxietyloelulózy fikátoru shell exhibits a condensate naftalensulfokyaelin antifiltrační additive according to the present invention a first point e.g. at 130 ⁰ 0 threefold lower filterability additive and the second point of the object of the invention fivefold lower filterability.

The antifiltration effects of the additive according to the invention are present in all cement-based tamponage mixtures, but most notably in tamponage mixtures made of slag-portland cements. They are the result of the syn-sergic effect of the components of the antifiltration additive, namely the dispersing effect on the cement and the thermostabilizing effect on the cellulose derivatives. The antifiltration effect of the additive according to the invention is shown in the following examples and reported as the filterability of the tamponage composition determined by the standard high-pressure filter test at an overpressure of 0.7 MPa. The lower the filterability value, i.e. the amount of filtrate passed through the filter baffle in 30 minutes, the more effective the antifiltration additive.

Example 1

To the mixture of 78.8% by weight class 230 slag-slag cement and 20% by weight finely divided silica flour was added the antifiltration additive of the invention, composed of 0.4% by weight hydroxyethyl cellulose and 0.8% by weight omega-sulfonated alkyl polyphenol binder condensate. After stirring for 20 minutes with water, supplied in a weight ratio of 0.5> 1 to the dry components, a cementitious tamponage suspension was formed, which was tested by a standard high-pressure filter procedure. At a pressure of 0.7 MPa and a temperature of 22 ^° C it flowed in 30 min. through a filter screen 15 om ^{3 of the} filtrate. At the same pressure and a temperature of 70 ⁰ 0 flowed over the same period 28ora ³ and at 130 ⁰ C, 37 cm ³ of the filtrate compared with the use of previously known antifiltrační additive consisting of hydroxietylceluló zy and condensate naftalensulfokyselin was filterability plugging slurry at 130 ⁰ C in triplicate higher.

Example 2

The same antifiltration additive as in the first example was applied to a mixture of 68.8% by weight class 250 slag-slag cement and 30% ground nutrient sand and a cementitious tamponage mixture having the same water weight ratio was formed.

At a temperature of 22 ^° C and a pressure of 0.7 MPa, 20 cm ^{3 of} filtrate flowed through the filter screen, at 70 ^° C 38 cm ³ , and at 130 ^° C 47 cm ^{3 of the} filtrate.

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Example 3

An antifiltration additive according to the invention consisting of 0.4% by weight of hydroxyethyl cellulose, 0.2% by weight of omega-sulfonated alkyl polyphenol polycondensate and 0.8% by weight of polycondensate of naphthalene sulfoacids was applied to Portland cement of class 400, 98.6% by weight. After stirring for 20 minutes with water, supplied in a weight ratio of 0.5> 1 to dry matter, a cement tamponage mixture was formed, which was tested in the same manner as in the first example. At 22 ⁰ C showed a 25 cm filtrate at 50 ⁰ C, 24 cm ^3, 70 ⁰ C and 26 cm ³ at a temperature of 100 ⁰ C, 27 cm ³ of filtrate.

Example 4

An antifiltration additive according to the invention consisting of 0.45% by weight of polyethylene glycol cellulose, 0.2% by weight of omega-sulfonated alkyl polyphenolic polycondensate and 0.8% by weight of naphthalene sulfoacid polycondensate was added to class 70 road cement in an amount of 98.45% by weight. The solidification retarder of the cement slurries was also applied in an amount of 0.1% by weight. The mixture was mixed with water in a weight ratio of 1 »0.5, and after stirring dvacstiminutévém filtrpresu tested on said high temperature in the same manner as in Examples 1 to 3 * at 70 ° C showed 24 om ³ of the filtrate at 120 ⁰ C 189 om ³ filtrate .

To compare the antifiltration effects of the additive according to the invention, a similar tamponage mixture was produced, differing only by the replacement of the omega-sulfonated alkyl polyphenolic polycondensate with the polycondensate of naphthalene sulfoacids. At a temperature of 120 ^° C and a pressure of 0.7 MPa, 234 cm ^{3 of} filtrate flowed through the filter baffle, ie by almost one fifth more.

Example 5

To the mixture of 98.4% Portland cement class 400 and 0.1% calcium gluconate was added an antifiltration additive according to the invention consisting of 0.5% hydroxyethyl cellulose, 0.3% omega-sulfonated alkyl polyphenol polycondensate and 0.7% % polycondensate of naphthalene sulfoacids. The cement tampon blend formed under the same conditions and with the same water weight ratio as in the first example was also tested in the same manner. It showed 99 cm ^{3 of} filtrate at 130 ^° C.

For comparison, an analogous experiment was performed as in Example 4. The omega-sulfonated alkyl polyol phenol polycondensate was replaced with a naphthalene sulfoacid polycondensate. This cementitious tamponage mixture also exhibited a one-fifth higher filterability, namely 119 cm ³ , at 130 ^° C.

Example 6

An antifiltration additive according to the invention consisting of 0.6% by weight of hydroxyethyl cellulose, 0.2% by weight of omega-sulfonated alkyl polyphenolic polycondensate and 0.8% by weight was applied to a mixture of 98.3% by weight of slag-portland cement of class 250 and 0.1% by weight of calcium gluconate. by weight of polycondensate of naphthalenesulfocyanate 403 selin. The cement tampon blend formed under the same conditions and with the same water weight ratio as in the first example showed 31 cm < ³ > of filtrate and at 130 ^° C 34 cm ^{1 2 3 of the} filtrate.

To compare the antifiltration effects of the additive according to the invention, a similar mixture was formed, except that the omega-sulfonated alkyl polyphenolic polycondensate was replaced by poles with a condensate of aaphthalene sulfoacids. Pilotability deteriorated sharply. The tamponate mixture exhibited 325 cm ^{3 of} filtrate at 120 ^° C and 0.7 MPa pressure and 292 cm ^{3 of} filtrate at 130 ^° C.

Any pure or technical type of water-soluble cellulose derivative formed by the action of an alkylone oxide on an alkali cellulose can be used to prepare the antifiltration of the additive according to the invention if its average degree of polymerization is greater than 200. Polycondensate of formaldehyde in any alkylpolyone alkyl chain. From the manufacturing point of view, it is advantageous to use condensates prepared from technical mixtures of polyalkylphenols, which are obtained for example in chemical processing of coal or coal tars, combustible shales, etc. Polycondensate of naphthalenesulfoacids can be obtained from formaldehyde polycondensates with naphthalene-, di- or trisulfoic salts.

The individual antifiltration components of the additive according to the invention can be applied to the cementitious tamponage mixture of cells in the dry state or dissolved in the mixing water.

Claims (2)

SUBJECT OF THE INVENTION CLAIMS 1. An antifiltration additive for a cementitious tamponage composition for deep wells, characterized in that it consists of a water-soluble cellulose derivative having an average polymerization degree higher than 200 resulting from the action of alkylonoxides on alkali cellulose, in particular hydroxyethylcellulose or polyethylene glycol cellulose; the ratio of both components is in the range of 1 to 0.5 to 1 to 12. 2. An anti-filtering additive according to claim 1, characterized in that it contains polycondensate of formal debyde and naphthalenesulphonic acids, in a weight ratio to the polycondensate of formaldehyde with alkylphenols sulfonated in the alkyl chain of 1: 0.1 to 1 s 1.