RU2319722C1 - Polymer-cement grouting mortar - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: grouting mortar, which can be used to reinforce oil and gas wells, contains, wt parts: cement 100, water-loss reducing additive (CFL-117) 0.4-0.8, reinforcing and adhesive additive (Konkrepol) 0.6-1.0, and water 42-50. Grouting mortar may further contain mineral extending additive, e.g. DR-100, 5-10 wt parts.

EFFECT: achieved creation of nonshrinking grouting composition.

2 cl, 4 tbl, 15 ex

Description

The invention relates to the oil and gas industry and can be used for fastening oil and gas wells.

A well-known cement slurry, which includes, parts by weight: cement - 100; OEC - 0.25-0.5; oxinaftolinesulfonic acid-formaldehyde resin (C-3) - 0.1-0.75; CaCI ₃ - 3.0; water - 50. ("Complex reagents for the treatment of cement slurries" V.M. Medentsev, A.K. Kuksov, M.O. Ashrafyan, Yu.V. Grinko, Journal of Oil Industry, N 7, 1997, p. thirty).

The specified cement slurry is intended for use under temperature conditions from 60 to 100 ° C.

However, the well-known cement slurry does not have sufficient thermal stability. When the temperature rises to 75 ° C, the water loss of the specified cement slurry increases two or more times. At this level of water loss during coagulation structure formation, the well-known cement slurry does not ensure its resistance to breakthrough by formation fluids.

In addition, the known solution is sedimentation unstable, which leads to the formation of vertical channels in the body of the cement sheath.

The closest technical solution chosen by the authors for the prototype is a polymer-cement grouting composition containing the following ingredients (parts by weight): cement - 100; hydroxyethyl cellulose - 0.3-0.5; melamine-containing product - 0.5-1.0; water - 40-50 (RF Patent No. 2149981, 1998). The grouting composition has a number of advantages, which include low filtration rates (water loss and sedimentation stability), high rheological characteristics.

A disadvantage of the well-known grouting mortar is low adhesion to the surface of the casing string and to the walls of the wells, insufficient bending strength of the cured cement stone and insufficient pressure gradient that withstands the grouting material, preventing breakthrough of formation fluids.

The aim of the invention is the creation of a non-shrinking cement composition devoid of these disadvantages. This goal is achieved in that the grouting mortar containing cement, polymer additive and water, characterized in that as the specified additive it contains a loss of fluid loss - CFL-117 and hardening and adhesion - Constolol in the following ratio, wt.h .:

Cement one hundred CFL-117 0.4-0.8 Constolpol 0.6-1.0 Water 42-50

In this case, the solution additionally contains a mineral expanding additive, for example DR-100, in the following ratio of components, parts by weight:

Cement one hundred CFL-117 0.8 Constolpol 1,0 Expanding additive 5-10 Water 42

The CFL-117 fluid loss reducer is a high molecular weight (5.0.10 ⁶ -5.8.10 ⁶ ) polyoxyethylene (Clearwater, Technical Information, ISO 9001 Certificate, Houston, Texas 77027, 2003). Adhesive additive Conconstol is a water-polymer system of poly-N-vinylamide (Certificate of Conformity No. TEK RU., ХП 06.Н00832, Certificate No. РОСС RU.0001. 03Ю00, 20.08.9). An expanding additive, for example DR-100, basically consists of a mixture of mineral oxides of Ca and Mg (TU 5744-002-59758749-06).

The specified ratio of the components of the cement slurry can reduce water loss and water separation, increase adhesion to pipe metal and reservoir rock, reduce gas and gas permeability, and increase the strength of cement stone. The use of the proposed well-soluble in water reagents with a complex effect does not complicate the process of preparing cement slurries during insulation work at drilling sites. The combination in the composition of the solution of the loss of fluid loss and an adhesive additive - high molecular weight N-polyvinylamide, resistant to polymineral aggression, gives cement mortars the characteristics necessary for the claimed composition.

To obtain the inventive cement slurry in laboratory conditions, the following substances were used:

1. Grouting Portland cement PTsT-1-G-CC-1 of the Sukholozhsky cement plant (GOST 1581-96).

2. Fluid loss reducer CFL-117 of the American company CLEARWATER Engineered Chemistry.

3. Strengthening and adhesive additive Constolol manufactured by LLC "Orgpolymersynthesis SPb" (TU 9365 001 13803633 20003).

4. The mineral expanding additive DR-100 (TU 5744-002-59758749-06).

The use of the selected ingredients with a complex effect improves the structural and rheological properties of cement mortars, increases the strength and adhesive properties of the cured grouting stone, and significantly increases the pressure gradient at which formation fluids do not break through the grouting material.

The essence of the invention is illustrated by the following examples.

Examples 1-3.

The preparation of cement mortars was carried out according to the standard method, GOST 26798.1-96.

0.8 g of CFL-117 and 1.0 g of Conconstol are added to 50.0 ml of water. In the resulting homogeneous solution, 100 g of cement, cement, is blended. After thorough mixing, the composition is kept in a thermostat at 75 ° C for 30 minutes, after which its rheological characteristics are determined. The selected mode of preliminary heating of the cement slurry is close to the conditions of coagulation structure formation when it is pumped into a well with a temperature of 85 ° C to a depth of 3200 m. After 7-day hydration of the cement test, the physicomechanical characteristics of the cured grouting material are determined.

In parallel, for comparison, a grouting solution was prepared that did not contain polymer additives (control experiment) and a solution obtained by the prototype. The rheological characteristics of cement slurries are shown in table 1.

As can be seen from the table, the proposed polymer-cement grouting composition in sedimentation stability (water separation) and in water yield exceeds the known composition. All other characteristics (flowability, thickening time) are close to the control composition and meet the requirements of GOST 26798.1-96. The flowability and thickening time of the proposed polymer-cement solution indicate its mobility and the availability in time required for trouble-free delivery of the solution to the well.

Tests of the rheological properties of the proposed polymer-cement mortar at 75 ° C indicate a high quality solution in moderate temperatures (up to 100 ° C).

Table 1. The rheological characteristics of the grouting compositions at 75 ° C (W / C = 0.42) Experience number Recipe, parts by weight ρ g / cm ³ Water loss, cm ^3/30 min Water separation% Spreadability by AzNII, cm τ _start hour τ _{final grip} hour one. cement-water (control) 1.92 105 5 210 2.2 3.0 2. cement 100 OEC * 0.5 melamine form. resin 1.91 7.5 0.6 220 2,3 3.3 MFAR 1.0 water 42 (prototype) 3. cement 100 CFL-117 0.8 1.92 2,8 0 230 3,5 4.4 konsrepol 1.0 water 42 * ENM brand hydroxyethyl cellulose

According to the recipes of experiments 1-3, standard samples were prepared and after 7-day hydration were tested for strength and adhesion properties. Physico-mechanical properties of cured cement compositions are shown in table 2.

table 2 Physico-mechanical characteristics of grouting compositions at 85 ° С Experience number Recipe, parts by weight The properties Σ _outgoing MPa Σ is _compressed. MPa Linear expansion.,% Adhesion to metal, MPa one. Cement water W / D 0.42 12.5 53.5 0 1.95 (control) 2. Cement 100 OEC * 0.5 Melamineform. 9.8 55.0 - 1.75 see IPAF 1.0 Water 42 (prototype) 3. Cement 100 CFL-117 0.8 13.3 58.7 0.15 3.93 Conspinol 1.0 Water 42

As can be seen from the data in table 2, the cement stone obtained according to recipe 3, in comparison with the control composition and the prototype, has increased compressive and bending strength, increased adhesion to the casing and the absence of shrinkage.

Examples 4-10.

The optimal ratio of the components of the developed grouting composition was determined based on the rheological properties of the polymer-cement grouting mortar (Table 3).

Table 3 Properties of polymer cement grouting solutions at 20 ° С. Example No. Composition, parts by weight per 100 parts by weight cement Cement mortar characteristics Water separation,% Water loss, cm ^3/30 min Spreadability by AzNII, mm τ _start hour CFL-117 0.2 four. constipol 0.5 2.9 16 > 250 2.0 water 50 CFL-117 0.4 5. konsrepol 0.6 0.5 4,5 > 250 2,5 water 47 CFL-117 0.8 6. konsrepol 1.0 0.5 2.0 240 3,5 water 45 CFL-117 0.8 7. konsrepol 1.0 0 1,0 230 3.8 water 42 CFL-117 1.0 8. konsrepol 1.15 0 0.5 190 3,5 water 42 CFL-117 0.45 9. konsrepol 0.7 3.0 1,5 > 250 2,5 water 42 10. konsrepol 1.0 4.0 36 > 250 2.0 water 42

The data presented in the table show that at a formation temperature in the range of 60-85 ° C, the optimal ratio of polymer components (per 100 parts by weight of cement) in the cement slurry is: CFL-117 - 0.4-0.8, and Constanzola - 0.6-1.0 parts by weight The water-cement ratio can vary from 0.42 to 0.50 depending on the required density of the cement slurry while maintaining the rheological characteristics that meet the requirements of GOST 26798. 1-96. Thus, an increase in the content of CFL-117 and constipol in the composition is more than optimal (experiment 8, Table 3) leads to a noticeable decrease in such an indicator as AzNII spreadability.

In the absence of one of the polymer additives in the grouting composition, for example CFL-117 (Example 10), the water loss of the cement slurry increases significantly. The resulting solution has a reduced sedimentation stability, as evidenced by the increased values of water separation, exceeding the requirements of GOST 26798. 1-96.

Studies have shown that with the exception of Conconstol from the composition, the adhesion of cement stone to the casing metal decreases from 3.93 to 2.05 MPa.

It should also be noted that the developed composition is characterized by a high initial strength of cement stone, which has increased ductility and resistance to acids and aggressive formation fluids (in particular, to the action of sulfate-containing formation waters).

Conducted on the installation of BPS-805 filtration tests of artificial cores made according to the recipes of examples 1-3 (table 2), showed the absolute gas permeability of 0.15; 0.03 and 0 mD, respectively. The lack of gas permeability of the sample obtained by the claimed method, indicates its high insulating properties. The pressure gradients that withstand the artificial water filtration cores obtained from the recipes of experiments 2 and 3 are 10 and 75 MPa, respectively. The data obtained indicate the high insulating properties of the proposed grouting composition, superior to foreign and domestic analogues in this class of grouting materials.

Examples 11-15.

As shown above (see table 2), the linear expansion of the proposed cement composition does not exceed 0.15%. However, it is known that for sealing polymer cement it is not enough to eliminate shrinkage deformation, and it is necessary to obtain the expansion effect during hardening to compress and seal the cement composition in the isolation zone.

Known technological methods for eliminating shrinkage deformation and obtaining cements with controlled shrinkage by using expanding additives. For this purpose, expanding additives CaO, MgO, and DR-100 were introduced into the composition of the composition. The rheological and physico-mechanical properties of polymer-cement solutions depending on the nature and content of expanding agents are shown in table 4.

Table 4 The effect of expanding additives on the rheological characteristics of polymer cement at 85 ° C (the content of polymer additives, parts by weight: CFL-117 - 0.8; Constipol-1.0) Experience number Additive, parts by weight per 100 parts by weight cement Rastek. according to AzNII, mm τ _{early grasp.} hour Tensile strength, in tech. 7 days Lanein. expansion,% Adhesion to metal, MPa Σ _outgoing MPa Σ is _compressed. MPa eleven. CaO, 5 250 2.40 14.0 53.9 +2.3 2.15 12. CaO, 10 235 2,35 15.7 55.9 +3.5 1,57 13. MgO, 10 240 2,30 15.0 57.0 +4.1 1.48 fourteen. DR-100, 10 250 2,50 13.0 47.9 +3.0 2.98 fifteen. DR-100, 30 > 250 2,55 13.3 42.7 +8.0 0

Based on the data obtained, it can be concluded that the introduction of expanding additives into the composition does not lead to a noticeable change in the rheological and strength characteristics of cement slurries, but significantly reduces the adhesion of polymer-cement stone (compare with Table 2). So the introduction to the composition of 30 parts by weight DR-100 leads to almost zero adhesion of the cement material. Moreover, linear expansion reaches 8%.

As is known from world practice, the linear expansion of cured cement stone should not exceed 3%. With a greater expansion in the cement stone under conditions of rock pressure, internal stresses and microcracks occur, leading to the destruction of the insulating material. From table 4 it is seen that the use of expanding additives DR-100 in the polymer-cement composition in an amount of not more than 10 wt.% With respect to cement leads to a 3% expansion of cement stone.

The preparation of the inventive polymer cement grout in the field is carried out according to the following scheme.

Two containers of 40-50 m each are delivered to the well (one for water for the preparation of the grouting composition, the second for selling the cement composition into the annulus) and full chemicals. Water should be fresh or slightly saline. The tank is strapped with water and with the TsA-320 pumping unit in a closed “do-it-yourself” circuit and begin to enter chemicals in the process of pumping mixing water in a closed cycle. CFL-117 is the first to be introduced, followed by konstrepol in the amount of 0.4-0.8 and 0.8-1.0 parts by weight. accordingly from the taken cement.

The prepared water is pumped in a closed circuit for another 1-2 hours to equalize the properties throughout the volume.

When using an expanding additive, cement is pre-mixed with DR-100.

Cement mixing, as well as all further work on the injection of polymer-cement grouting composition and selling it into the annulus, are carried out by the grouting team according to the standard work plan developed by the grouting company and approved by the drilling department.

Claims (2)

1. A grouting mortar containing cement, a polymer additive and water, characterized in that as the specified additive it contains a fluid loss reducer CFL-117 and hardening and adhesive Conconstol in the following ratio of components, parts by weight: Cement one hundred CFL-117 0.4-0.8 Constolpol 0.6-1.0 Water 42-50 2. Grouting mortar according to claim 1, characterized in that it further comprises a mineral expanding additive, for example DR-100, in the following ratio of components, parts by weight: Cement one hundred CFL-117 0.8 Constolpol 1,0 Expanding additive 5-10 Water 42