SU840294A1 - Method of preparing plugging composition - Google Patents

Description

one

The invention relates to the attachment of oil and gas wells, namely to the preparation of a tamping material for cementing under conditions of hydrogen sulfide aggression.

A known method for the preparation of a cement slurry by mixing in corrosion-resistant cement cements 1.

The disadvantage of this method is the limited choice of cements for these conditions.

There is a known method of preparing a cement slurry by introducing a fluid into the fluid interrupting it. Brines of various salts are used as a mixing fluid. The method allows to obtain a cement stone that is corrosion resistant to salt aggression 2.

However, the cement stone formed from the solution prepared by the method does not possess corrosion resistance in the hydrogen sulfide environment, i.e. does not provide reliable mounting of wells containing hydrogen sulfide in formation fluids.

The purpose of the invention is to increase the strength and anti-corrosion properties of the cement stone in the conditions of hydrogen sulfide aggression.

The goal is achieved by the fact that the liquid of the land is saturated with hydrogen sulfide before being introduced into the recipient.

The mixing of the fluid on the pre-planed hydrogen sulfide fluid provides an increase in the corrosion resistance of the cement stone to hydrogen sulfide aggression. This process can be attributed to the fact that when the fluid is mixed into a fluid saturated with hydrogen sulfide, calcium sulphides are formed, which have the burning properties.

The method for preparing the cement slurry is as follows.

The mixing fluid is pre-saturated with hydrogen sulfide to a concentration of 3 g / l (full saturation) by bubbling the latter through the liquid, after which the cement material is mixed on it.

Studies on the strength and corrosion resistance of cement stones from various types of cements, mixed with liquids of different composition, are carried out in both fresh and hydrogen sulfide environments, which is saturated to the concentration of 3g / l tap water. The concentration of hydrogen sulphide decreases with aging of the cement Kama; therefore, 4y daily by bubbling hydrogen sulfide, its concentration increases to the baseline.

In tab. Figure 1 shows the change in the strength of cement cement for hot wells, depending on the mixing fluid; in tab. 2 shows the change in the strength of the cement stone from the expanding cement depending on the gate fluid and the storage medium; in tab. 3 - dependence of the cement stone strength (FROM slag cement SHPSS-120 on the gate fluid and storage medium.

Table

100 cement

Presna.

60 fresh water

Hydrogen sulfide

100 cement

Presna

Hydrogen sulfide60 water saturated with on

100 cement

Presna

60 emulsions

Hydrogen sulfide on

100 cement

Presna

60 emulsion, saturated with hydrogen sulfide. (, S on.

Composition of tampons

Solution medium, parts by weight storage

Presna

Hydrogen sulfide

Presna

Noah

Hydrogen sulfide

244, 2

293.7

203, i

223.2 235.3 186.9

243.3

217.8 199.4 245.2

201.3

151.8 246.7 180.4

258.2

221Л

table 2

Compressive strength during storage in the first three months, kgf / cm

48.8

36.0

51.4

35.6 42.9 50.5

45.4

57.7

100 cement

Fresh cement stone, formed from cement for hot wells shut in fresh water, has a reduced strength when stored in a hydrogen sulfide environment (Table 1, mixture 1), while cement bolting on a hydrogen sulfide-containing fluid increases the strength of the stone in during the whole time tested or stored in a hostile environment (Table. 1, mixture 2). The formation of calcium sulfides in this case is confirmed by the results of studies of the strength characteristics of the cement stone stored in fresh water (Table 1, the mixture in which leaching occurs

Table 3

14.0

26.0

14.5 calcium sulphides, which leads to a slower increase in strength in the first three months. It should be noted a significant increase in the "corrosion resistance of cement stone formed from cement, mixed with an emulsion saturated with hydrogen sulfide (Table 1, mixture 4). The hardening tendency of the cement stone prepared on a liquid saturated with hydrogen sulfide is also preserved for other types of cements, such as the cement oil expanding cement of the Leningrad Experimental Plant (Table 2) and slag SHPSS-120 (Table 3).

As shown by the results of a study of the strength of a stone formed from expanding cement, mixed with water saturated with hydrogen sulfide, the samples stored in the pressing medium are also increased. 2, the mixture 2) At the same time, the strength of the samples prepared on hydrogen sulfide, water and stored in the same, increases more intensively than the control stored in fresh water (Tables 2 and 3, mixture 2).

Identical results obtained for practically all types of tested cements, and for cement for hot beds at various water-cement ratios — (Table 4) indicate a general pattern explained by the formation of calcium sulfides.

Studies have shown that the strength of samples prepared with fresh liquid, preserved in a hydrogen sulfide environment, is 15–25% lower than the strength of control samples stored in a fresh environment.

Thus, the proposed method of preparing the cement slurry has great advantages over the known ones and allows the het to increase the strength and corrosion resistance of the cementing stone in the hydrogen sulfide environment and reduce its permeability, thereby eliminating the ecolumn flows and manifestations and increasing the durability of the lining.

Claims (2)

1.Bulatov A.I. Backing materials and technologies for cementing squigkin. M., Nedra, 1977, p. 258259. 2.Bulatov A.I. Tampon materials and cementing technologists of skvs1zhin. M ,, Nedra, 1977, p. 236 (prototype).