RU2504568C1 - Expanding plugging composition - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: proposed composition comprises grouting cement, fine inorganic additive, hydroxyethylcellulose, sodium or potassium chloride and water at the following ratio of components, wt %: grouting cement - 75.0-85.0, fine inorganic additive - 15.0-25.0, hydroxyethylcellulose - 0.3-0.6, sodium or potassium chloride - 5.0-10.0, water - 45.0-55.0. Said fine inorganic additive represents commercial fine natural chalk or ground dust-like quartz or fine siliceous filler Said hydroxyethylcellulose represents nonionic grades like "Натросол" 250 GXR, or "Натросол" 250 MX, or "Натросол" 250 EXR.

EFFECT: higher isolation properties plus lower contraction.

3 cl, 1 ex, 1 tbl

Description

The invention relates to grouting compositions for cementing casing strings in oil, gas and gas condensate wells.

Known grouting composition containing Portland cement, superplasticizer C-3, sulfacell and water / Patent No. 2136843, ЕВВ 33/138, publ. 09/10/1999 /.

The disadvantage of this composition is the low insulating ability due to the lack of expansion of the stone and increased magnitude of contraction.

The closest in composition and purpose is a grouting composition containing grouting cement, a stabilizing reagent, a mineral additive and water in the following ratio of components, parts by weight:

Grouting cement one hundred Reagent - stabilizer 0.2-1.2 Mineral supplement 2.0-3.0 Water 40-50

/ Patent No. 2256775, ЕВВ 33/138, publ. July 20, 2005 /.

The disadvantage of this composition is the lack of expansion during hardening into stone and a high value of contraction, therefore, a decrease in insulating ability.

The absence of expansion during hardening of the composition does not allow the formation of intense contact of the stone with the bounding surfaces and provides high tightness in the annular space in the presence of a mud filter cake, which, together with contraction, can lead to fluid manifestations or inter-reservoir flows. In the process of contraction and the development of vacuum, the mud mud cake is dehydrated, shrinkage and cracking are formed, but there is no possibility of compensating for changes in its properties due to the absence of sealing action from the hardening stone without expansion of the grouting stone. In addition, as a result of contraction rarefaction and a decrease in pressure in the cementing interval, the likelihood of penetration of the formation fluid (gas) into the annulus increases with further migration to the overlying (underlying) permeable formations or to the wellhead.

When creating the invention, the problem was solved of improving the quality of fastening of casing strings in the interval of productive formations with moderate temperatures in the range from 50 to 100 ° C.

The technical result of the invention is to increase the insulating ability of grouting mortar based on expanding grouting composition due to its expansion during hardening into stone and at the same time reducing contraction.

The solution of the problem and the technical result is achieved by the fact that the expanding grouting composition includes grouting cement, a finely divided inorganic additive, hydroxyethyl cellulose, sodium chloride (NaCl) or potassium chloride (KCl) and water in the following ratio of components, parts by weight:

Grouting cement 75.0-85.0 Fine Inorganic Additive 15.0-25.0 Hydroxyethyl cellulose 0.3-0.6 Sodium Chloride or Potassium Chloride 5.0-10.0 Water 37.4-47.7

As a finely divided inorganic additive, the expanding grouting composition contains natural technical dispersed chalk (MTD-2), or powdered silica quartz (Quartz B), or finely siliceous aggregate (KRTZ).

As hydroxyethyl cellulose, the expanding grouting composition contains nonionic grades of hydroxyethyl cellulose such as Natrosol 250 GXR, or Natrosol 250 MX, or Natrosol 250 EXR.

The following were used as finely dispersed inorganic additives: natural technical dispersed chalk according to TU 5743-008-05120542-96, which is a white powdery product obtained by crushing, drying, and fine grinding of natural calcium carbonate; powdered quartz according to GOST 9077-82, which is a solid natural material of light gray color with a high degree of dispersion; fine silica aggregate according to TU 5712-046-00187085-2006, which is a light brown powdery product obtained by fine grinding of natural silica.

As hydroxyethyl cellulose, nonionic grades of hydroxyethyl cellulose of the type Natrosol 250 GXR, Natrosol 250 MX, Natrosol 250 EXR according to TU 2231-001-21095737-2005, which are granular powders that quickly dissolve in water, forming solutions of various viscosities, were used. The typical Brookfield viscosity of 2% aqueous solutions of additives at 25 ° C is: 50-105 mPa · s for Natrosol 250 EXR, 250-450 mPas for Natrosol 250 GXR, 4500-6500 mPas for Natrosol 250 MX.

Sodium chloride according to GOST 4233-77 or potassium chloride according to GOST 4568-95 was used.

The basic properties of grouting mortar and stone were determined at a temperature of (75 ± 3) ° C in accordance with GOST 26798.1-96 “Cement grouting. Test Methods. " The density of the cement slurry was determined by a pycnometer, flowability by a cone shape, water separation in two cylinders with a volume of 250 ml, the tensile strength of the stone in bending and compression — on a testing machine for determining the bending / compression strength model L11V2 No. 07003613 (Italy, Controls company srL "), contraction, expansion and shrinkage of cement slurry during hardening into stone - on the device model 4268 ES (USA, Chandler Engineering).

Expanding grouting composition was prepared as follows. Sodium chloride or potassium chloride and hydroxyethyl cellulose were dissolved in water with stirring on an MM-5 magnetic stirrer until completely dissolved. The dry mixture was prepared by manually mixing the cement and finely divided inorganic additives in predetermined proportions. Then, in an aqueous solution of reagents, the dry mixture was mixed in a laboratory mixer SL-1 according to GOST 26798.1-96. After that, the parameters of the solution were measured and the properties of the formed stone were determined.

The prototype solution is also prepared in laboratory conditions and its parameters are measured.

Example. To prepare an expanding grouting composition (table, composition 9) it is necessary to take 427 g of water, 70 g of NaCl, 3 g of Natrosol 250 GXR, then prepare a dry mixture of 800 g of grouting Portland cement and 200 g of MTD-2. The closed composition is mixed for three minutes and determine the density, spreadability, water separation. The solution is poured into molds to determine the strength of the stone in bending, compression and in the cell of the 4268 ES device for determining contraction, expansion and shrinkage at a temperature of (75 ± 3) ° C.

The prepared composition has a density of 1.93 g / cm ³ , spreadability of 189 mm, water separation of 0.0 ml, the strength of the stone in bending 6.5 MPa, the strength of the stone under compression of 33.2 MPa, the expansion of the stone 1.26%, contraction of the solution at hardening in stone - 2.0

Examples of preparation and testing of the remaining compositions shown in the table are similar to the above.

To identify the distinguishing features and positive effect, the mass ratios of the ingredients were changed.

The combination of grouting cement, hydroxyethyl cellulose, sodium chloride or potassium chloride, a finely divided inorganic additive and water as a result of the manifestation of a synergistic effect gives the grouting composition a new property - a combination of expanding ability and low contraction during stone setting.

As can be seen from the table, the inventive expanding grouting composition with an optimal ratio of components exceeds the analogues known from the prior art, namely, it is characterized by expanding ability and low contraction during hardening to stone.

Claims (3)

1. An expanding grouting composition, including grouting cement, a finely divided inorganic additive, hydroxyethyl cellulose, sodium chloride or potassium chloride and water in the following ratio, wt.h .:
Grouting cement 75.0-85.0 Fine Inorganic Additive 15.0-25.0 Hydroxyethyl cellulose 0.3-0.6 Sodium Chloride or Potassium Chloride 5.0-10.0 Water 45.0-55.0 2. The expanding grouting composition according to claim 1 contains, as a finely dispersed inorganic additive, natural technical dispersed chalk, or powdered silica, or fine-silica aggregate. 3. The expanding grouting composition according to claim 1 contains nonionic grades of hydroxyethyl cellulose such as Natrosol 250 GXR, or Natrosol 250 MX, or Natrosol 250 EXR.