RU2323242C2 - Complex reagent for grouting mortars - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: complex reagent contains 88.9-90.1% poly(vinyl acetate) dispersion, 0.9-2.22% nitrilotrimethylphosphonic acid, 4.44-4.50% dibutyl phthalate, and 4.44-4.50% ethylene glycol.

EFFECT: improved strength and adhesion properties of grouting mortar.

1 tbl

Description

The invention relates to the fastening of oil and gas wells in difficult geological and technical conditions on waterfields, large angles of withdrawal from the vertical, in the presence of caverns and stagnant zones and can be used for the preparation of grouting mortars with high strength and adhesive properties and their application in these above conditions.

A known solution based on Portland cement and water, including nitrilotrimethylphosphonic acid (NTP) and asbestos as a complex reagent (AS No. 939729, ЕВВ 33/138, 10.10.80).

However, this solution is environmentally hazardous because it contains asbestos, and the cement stone from this solution is not strong enough and has low adhesion to bounding surfaces.

These drawbacks of the cement slurry are partially eliminated by using a complex reagent containing polyvinyl acetate dispersion (PVAD) and a salt of NTF - corilate (item No. 2179231 ЕВВ 33/138, 02/10/2002). This complex reagent in technical essence is close to the proposed one and can be taken as a prototype.

The disadvantage of this reagent is that when it is used, the cement stone has insufficient strength and adhesion to bounding surfaces.

The objective of the invention is to develop a reagent that increases the strength and adhesive properties of cement slurry - stone at temperatures up to 100 ° C.

The essence of the invention lies in the fact that the reagent for cement slurries containing PVAD and the additive contains NTF, dibutyl phthalate (DBP) and ethylene glycol (EG) as additives in the following ratio, wt.%:

PVAD 88.9-90.1 NTF 0.9-2.22 DBF 4.44-4.5 EG 4.44-4.5

From the patent and scientific and technical literature, we do not know the reagent for cement slurries containing the combination of the above components in the proposed quantitative ratio, which allows us to conclude that the claimed technical solution is new.

PVAD is made in accordance with GOST 18992-80.

NTF is produced according to TU 6-09-52-83-86, is used as a moderator of the setting time of cement slurries.

DBF is produced according to TU 6-09-985-81.

EG is produced according to GOST 19710-83.

A complex reagent for cement slurries is obtained by mixing PVAD, NTF, DBP and EG. At the same time, NTP is a more active component of the reagent (pH <1) than the salt of this acid - corilate (pH = 2.5-3.5). The acid interacts with the components of the reagent with the formation of new modified substances with chemically active groups. The resulting chemically active reagent of a complex composition with acidic properties interacts with cement silicates, activates their hydration and hardening with an increase in strength and adhesive properties. DBP, EG and their derivatives with an acid disperse polyvinyl acetate, plasticize the grouting solution, and suppress foaming. In general, the reagent effectively clogs, compacts the cement stone, as a result of which its strength and adhesion increase. Each component of this reagent individually either slows down the thickening, or reduces the strength and adhesion below the required limits (table). Together, in the complex reagent due to neoplasms, a synergistic effect and the achievement of the task are provided.

In laboratory conditions, a complex reagent is prepared by mixing the calculated amounts of components, followed by stirring with a stirrer until a homogeneous mass is obtained, then it is dissolved in water and the cement is mixed, and the properties of the cement grout are determined. Samples harden within 24 hours. Adhesion is determined by extruding a cement sample from a steel cage when creating a press load.

The table shows the results of determining the strength and adhesion of cement slurry - a stone with reagent additives, with a different ratio of components that increase the strength of the stone and its adhesion to the casing metal to the greatest extent.

It was found that in the complex reagent the optimal content is PVAD 88.9-90.1%, NTF 0.9-2.22%, DBP and EG 4.44-4.5% each. Outside of these concentrations, the reagent causes an increase or decrease in the thickening time, a decrease in the strength and adhesion of the cement mortar - stone to technologically unacceptable values.

The addition of 1% of the complex reagent to the mass of cement under the same hardening conditions increases the strength and adhesion of the cement stone to a greater extent than the reagent of the prototype. In this case, the thickening time is within technologically necessary limits.

From the existing level of technology, we do not know that the ingredients that make up the complex reagent in a given ratio provide the above properties, which allows us to conclude that the proposed technical solution meets the criterion of "inventive step".

An example of the use of grouting composition in field conditions.

During the mixing of grouting mortar, a pre-prepared suspension containing PVAD, NTF, DBP and EG is dissolved in the gauges of the cementing unit, in which the volume of mixing liquid required for cementing is collected.

The proposed composition of the cement slurry was tested in field conditions at three wells of the Tevlinsko-Russkinskoye and two wells of the Ravenskoye fields.

The interval of cementing in the wells averaged 2,400-2,600 m vertically, the formation temperature at the bottom was 68 ° C, the required volume of grouting mortar was 7 m ³ , and the required cement mass PCT IG 10 tons.

On the basis of the cementing plant 6 hours before the start of cementing, a reagent suspension was prepared, consisting of PVAD, NTF, DBF and EG, mixed in the following amounts:

- PVAD - 100 kg (90.1%);

- NTF - 1 kg (0.9%);

- DBP - 5 kg (4.5%);

- EG - 5 kg (4.5%).

Prepared complex reagent in the amount of 1% to the mass of cement was introduced into the measuring devices of the cementing unit, in which 4 m ^{3 of} technical water intended for mixing grouting mortar was drawn. After circulating the resulting solution for 5 minutes, the cement slurry was prepared. At the same time, grouting and technological indicators of mortar and stone were as follows:

density 2000 kg / m ³ water separation 0% strength (after 1 day at 68 ° C), bending / compression 10.2 / 35.8 MPa water loss 90 cm ^3/30 min thickening time 100 min spreadability 200 mm cement stone adhesion to bounding surface 4.2 MPa.

Cementing of the test wells took place without complications.

According to the results of geophysical studies (ACC), an increase in the density of contacts of cement stone with the column and rock was established, there are no inter-layer flows.

Thus, the technical result of the invention is to improve the quality of the fastening of wells and separation of layers.

Information sources

1. AC No. 939729, ЕВВ 33/138, dated 10/10/1980

2. RF patent No. 2179231 of 02/10/2002 priority of 04/18/2000

Table The composition of the reagent, the properties of the cement slurry No pp The composition of the reagent,% Properties of cement slurry - stone with the addition of 1% reagent when hardening for 24 hours PVAD NTF DBF EG Corilat Hardening temperature, ° С The strength of the stone in bending, MPa The strength of the stone in compression, MPa Adhesion of stone to metal, MPa Thickening time at a pressure of 30 MPa, min Notes one - - - - - 75 3.6 9.8 1,5 150 2 one hundred - - - - 75 2.6 7.1 1,1 370 3 - one hundred - - - 75 - - - - Does not thicken four - - fifty fifty - 75 4.1 11.8 2,3 310 5 85.0 0.6 7.2 7.2 - 75 6.8 19,4 9.7 90 6 90.1 0.9 4,5 4,5 - 75 5.5 26.6 8.6 180 7 88.9 2.22 4.44 4.44 - 75 3.6 22.5 7.7 201 8 92.0 3.0 2,5 2,5 - 75 2,4 8.8 3.3 482 9 90.1 0.9 4,5 4,5 - one hundred 12.6 42.0 6.2 161 10 88.9 2.22 4.44 4.44 - one hundred 7.8 30,0 5.5 188 eleven 99.6 - - - 0.4 75 - - 3.0 203 According to the prototype 12 99.6 - - - 0.4 one hundred - - 4,5 one hundred According to the prototype

Claims (1)

Complex reagent for cement slurries containing a polyvinyl acetate dispersion and additives, characterized in that it contains nitrilotrimethylphosphonic acid, dibutyl phthalate and ethylene glycol as additives in the following components, wt.%: Polyvinyl Acetate Dispersion 88.9-90.1 Nitrilotrimethylphosphonic acid 0.9-2.22 Dibutyl phthalate 4.44-4.50 Ethylene glycol 4.44-4.50