RU2426866C1 - Polymer backfilling composition for isolation of water influx in low temperature oil and gas wells - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: composition contains carbamide-formaldehyde resin, acid hardener and filler. As hardener there is used resorcin and ferro-chrome-lignosulphonate, and as filler there is used carbon white CW-120 or talk, or rubber powder, or chalk at the following ratio of components, in weight shares: carbamide-formaldehyde resin 100; resorcin 7-15, ferro-chrome-lignosulphonate - FCLS-M 1.5-25, filler 3-8.

EFFECT: reduced water loss of backfilling solution and increased strength and adhesion characteristics of cured composition.

2 cl, 1 tbl, 20 ex

Description

The invention relates to the oil and gas industry, in particular to cementing materials for waterproofing in production wells in order to reduce the water content of the produced products.

The most widely used grouting compositions based on cement mortars in a number of cases cannot be effective due to the low filterability of the mortar and the inability to penetrate the formation to a sufficient depth; high density, which can cause the absorption of cement and hydraulic fracturing; high filtration (deterioration of the mobility of the solution, colmatization of the productive zone), insufficient mechanical and impact strength (cracking of the stone during repeated perforation), etc.

Recently, for the isolation of absorbing horizons, polymer grouting materials based on phenol-formaldehyde, urea-formaldehyde, furan, polyurethane, epoxy, polysiloxane resins, etc. / are widely used / K. Strizhnev, V. A. Strizhnev "The choice of cementing material to justify the technology of repair work." - Drilling, 2006, No. 9, p.108-111 /.

The accumulated field experience in the use of polymeric materials allows us to distinguish the following main areas of their use:

- plugging annular space in the presence of formations prone to absorption and hydraulic fracturing under the action of solutions with high density;

- elimination of intense absorption of cement slurry of high density;

- plugging of absorbing horizons, composed of low permeability rocks and in the presence of highly aggressive reservoir fluids;

- Prevention of sand removal from weakly cemented reservoirs.

Among a wide selection of polymer grouting materials and compositions based on them, carbamide (urea-formaldehyde) compositions are widely used as the cheapest. Thus, the method of fastening the near-wellbore zone for hardening fine-grained sands and waterproofing rocks using the creation of a permeable filter based on cured urea-formaldehyde resins of the KF-Zh, M-70, etc. brands has become widespread. The compounds are widely used in construction.

To carry out insulation work in oil wells, a polymer grouting composition is proposed, consisting of a urea-formaldehyde resin, an acid hardener in the form of silicofluoric acid or its sodium salt and a solvent — alcohols of the C ₁ -C ₄ group, or a mixture of alcohol from the C ₁ -C ₄ group with water , or water / Pavlychev V.N., Emaletdinova L.D. and other polymer grouting composition. Pat. RF №2167267, 2001 /.

As can be seen from the above material, all formulations contain acid hardeners (hydrochloric, phosphoric, silicofluoric acid, etc.), or acid salts (aluminum chloride, aluminum sulfate, ferric chloride). A common disadvantage of acid curing grouting compositions is their high corrosivity to rock, cement stone, casing metal. Introduction to the composition of the solvent in the form of alcohol or water reduces the concentration of the resin, thereby increasing the water yield of the solution and reducing the strength characteristics of the cement stone.

The closest in technical essence to the claimed grouting composition is a composition based on urea-formaldehyde resin KFZH containing aluminum hydrochloride and zeolite as a filler to eliminate shrinkage / Pavlychev V.N., Umetbaev V.G. Emaletdinova L.D. and other polymer grouting composition. Pat. RF №2212520, 2003 /.

The disadvantages of this method include:

- the acidic environment of the cement composition (the pH of the commodity solution of aluminum hydroxyl chloride is in the range of 0.8-2.0), which negatively affects the strength of the cement stone, corrosion of the metal of the casing strings, and also limits its use in wells in the presence of carbonate rocks;

- short curing time of the grouting composition, varying from 0-50 to 6-00 hours, which is not enough even to lose the fluidity of the composition - the time required to prepare the composition, pump it into the tubing and sell it into the leakage interval;

- the introduction of a filler in the composition in the form of zeolite does not provide sufficient strength properties of the cured composition.

In addition, the disadvantages should also include the high yield of the polymer suspension, which leads to filtering of the filler when the composition is injected into the leakage interval.

The technical result of the present invention is the development of a method of non-acid curing of urea-formaldehyde resin of the resol type SF-HC, reducing the loss of grouting fluid and increasing the adhesive and strength characteristics of the cured composition.

The specified technical result is achieved by the fact that in the known polymer grouting composition comprising urea-formaldehyde resin, an acid hardener and a filler, according to the invention, resorcinol and ferrochrome lignosulfonate (FHLS-M) are used as a hardener, and wood flour or white soot BS-120 is used as a filler , or crumb rubber, or chalk, or talc, in the following ratio of components, parts by weight:

urea-formaldehyde resin one hundred resorcinol 7-15 FHLS-M 1,5-25 filler 3-8

The use of resorcinol and FHLS as the hardener instead of acid allows the composition to be cured in the temperature range of 20-60 ° C, eliminates the destruction of cement stone and significantly reduces its corrosion activity.

Resorcinol in the composition has two functions: a urea-formaldehyde resin modifier, leading to a decrease in solubility in hydrocarbons and an increase in the acid resistance of the cured composition, and a cocatalyst process.

FHLS in the grouting composition also performs two functions: a curing catalyst and a structurant. Structuring the reaction mixture leads to an increase in the viscosity of the solution and to the formation of a sedimentation-stable system (when a filler is introduced into the solution). This allows you to significantly reduce the fluid loss of the solution, which compared with the prototype is reduced by 4 times.

The KF-NS carbamide resin used is a homogeneous white suspension in accordance with GOST 2223-003-55093129-2009. Resorcinol technical GOST 997074 - a colorless crystalline substance, readily soluble in urea-formaldehyde resin. FHLS-M according to TU 2458-015-20672718-2001 is a modified product of the interaction of lignosulfonates with chromium and iron salts and is a brown water-soluble powder.

The grouting composition in comparison with the prototype has a neutral character of the reaction mixture, is characterized by homogeneity, low viscosity (conditional viscosity 15-30 sec according to VZ-246, nozzle diameter 4 mm), with adjustable terms of loss of fluidity and curing in the temperature range of 20-60 ° C . During the curing process, a homogeneous insulating material is formed without shrinkage, with increased mechanical strength and adhesion to the rock and metal compared to the prototype, resistant to the action of acid and aqueous dissolving salts.

When studying the properties of polymer grouting compositions, the following parameters were determined:

- viscosity according to VZ-246 (4 mm), s;

- an indicator for filtering VM-6 ^(cm3 / 30 min);

- bending strength, MPa (GOST 26798.1-96);

- adhesion to metal, MPa.

The adhesive properties of the formed cured material with the metal surface were determined on a device with a cylindrical ferrule and punch according to the method / Danyushevsky B.C., Aliev P.M., Tolstykh M.F. Reference guide for cementing materials. - 2nd ed. reslave. and add. - M. "Nedra", 1987. - p. 352-353 /.

Below are examples confirming the possibility of carrying out the invention.

Example 1

100 g of urea-formaldehyde resin with a viscosity of 21 s (at 20 ° C) was placed in the flask. Then, with the stirrer working, 10.0 g of resorcinol was introduced into the flask. After resorcinol was dissolved for 10 minutes, 2.0 g of FHLS-M was gradually added over 5 minutes. Stirring was continued until the modifier was completely dissolved within 20 minutes. The viscosity of the solution was 75 s. A filler — BS-120 white carbon black in an amount of 4.0 g — was gradually introduced into the resulting structured solution over a period of 5 minutes. Stirring was continued for another 5 minutes using a paddle mixer at a speed of 800 rpm.

After preparation, tests were conducted on a solution of water loss (F), which was 26 cm ^3/30 min. Fluid loss cement slurry known (prototype), which consists of urea-formaldehyde resins, gidroksohloristogo alumina and zeolite, under the same conditions was 103 cm ^3/30 min.

The resulting suspension was placed in a heating cabinet with a temperature of 55 ° C and periodically observed for a change in the consistency of the grouting composition. The time of fluidity loss was determined from the moment of mixing of the components to the moment of loss of mobility by the absence of a menix shift when the vessel with the reaction mixture was tilted. The full cure time was determined by the absence of bursting of the cement material when pressed with a needle.

The loss of fluidity occurred after 4 hours, and the complete curing of the composition occurred in 48 hours, and the solidification of the sample occurred without shrinkage. The resulting stone has satisfactory strength properties, high chemical resistance in saline water and a solution of hydrochloric acid, significantly exceeding the resistance of cement stone. After 2 days of storage of the cured samples in formation water at 55 ° C, the adhesion with the metal was 1.6 MPa (under similar conditions for cement stone without additives, this value does not exceed 0.9-1.0 MPa).

Example 2 (prototype)

For composition (parts by weight):

urea-formaldehyde resin one hundred hydroxychloride aluminum fifty zeolite twenty

the adhesion obtained under similar conditions with example 1 cured stone with a metal surface was 0.18 MPa, which is significantly lower than in the developed composition (see example 1).

Examples 3-19

According to the method described in example 1, polymer grouting compositions were prepared and, in the temperature range of 20-60 ° C, formulations with acceptable loss of fluidity and hardening of grouting stone suitable for RIR were installed. The results are shown in the table.

The data presented in the table show that the transition time of the developed polymer cement composition to a non-fluid state (resists) in the range of operating temperatures of 20-60 ° C is from 2.25 to 8 hours, which is sufficient for preparing the composition, injecting and selling it in the interval leaks. Inert fillers introduced into the grouting composition (BS-120 white carbon black, talc, crumb rubber, chalk) do not have a noticeable effect on the curing rate, but contribute to a decrease in water loss and shrinkage, and an increase in the strength characteristics of grouting stone.

Since filtration rate (F) of freshly prepared cement slurries of Examples 3 and 4 was 76 and 34 ^cm3 / 30 min, respectively; in the presence of 4 parts by weight filler F decreased by more than 2 times.

The filtration rate of cement slurries also depends on the content of FHLS-M: with an increase in the content of FHLS-M from 5 to 10 parts by weight. (Examples 12-14) reduces fluid loss from 30 to 16 cm ^3/30 min.

In addition to reducing water loss, the introduction of a filler in the composition leads to an increase in the strength characteristics of the cured grouting composition. So the strength under static bending of the cured samples of examples 3 and 4 was 7.3 and 8.6 MPa, respectively (for example 2, it did not exceed 5.0 MPa). For cement of the PTsT-I-G grade without additives under similar conditions, the strength under static bending was 7.0 MPa.

At higher temperatures (above 60 ° C), it is not possible to obtain non-shrinking material in an acceptable time period for the loss of fluidity necessary to conduct RIR in production wells.

Example 20

To conduct RIR in the zone of violation of the production string, leakage of the cement ring or the shut-off formation, the necessary ratio of components for the preparation of cement slurry is selected depending on the temperature of the isolation zone. In the measuring unit of the cementing unit CA-320, a solution is prepared in the following sequence of operations: the required amount of resin is pumped from the barrels, with constant stirring, resorcinol is added to it and, after dissolution, the FHLS-M reagent. Stirring is continued until a homogeneous liquid is formed.

If necessary, depending on the conditions of plugging, filler is added to the solution and the composition is homogenized.

The prepared cementing composition for tubing is pumped into the violation zone and the well closes for 24-48 hours for curing. Then the well is put into operation and put into operation.

Thus, the proposed polymer grouting composition corresponds to quality indicators, allowing it to be used for conducting RIR during operation and drilling of low-temperature wells.

Claims (2)

1. A polymer grouting composition comprising a urea-formaldehyde resin, an acid hardener and a filler, characterized in that resorcinol and ferrochrome lignosulfonate are used as a hardener in the following ratio of components, parts by weight:
urea-formaldehyde resin one hundred resorcinol 7-15 ferrochrome lignosulfonate FHLS-M 1,5-25 filler 3-8 2. The polymer grouting composition according to claim 1, characterized in that as a filler using white carbon black BS-120, or talc, or rubber crumb, or chalk in an amount of from 3 to 8 parts by weight