RU2640854C1 - Method of remedial cementing operations in well - Google Patents

Abstract

FIELD: oil and gas industry.SUBSTANCE: method of remedial cementing operations in wells includes preparing and injecting water-insulating composition into the well, containing, wt %: acetone-formaldehyde resin - 20.0-40.0, alkali drain of caprolactam production - 45.0-60.0 and 10% sodium hydroxide solution - 15-20.0. To prepare the water-insulating composition, alkali drain of caprolactam production is mixed with 10% sodium hydroxide solution and added with stirring to acetone-formaldehyde resin. The produced water-insulating composition is pumped into the well, after which it is left for gelling for 24-48 hours.EFFECT: improved efficiency of the method of remedial cementing operations by increasing the radius of water-insulating screen and increasing the coverage of action, extended time interval for gel formation, and reduced duration and labour intensity of operations.1 tbl, 3 ex

Description

The invention relates to the oil industry and can be used for repair and insulation works (RIR) in the well.

A known method of isolation and limitation of water inflow into wells (Patent RU No. 2272905, IPC ЕВВ 43/32, publ. 03/27/2006, bull. No. 9), including the injection into the injection or production well of an insulation material based on a cured in reservoir conditions polymer , selling it and aging for the period of curing and curing. As the specified material using a water-soluble polymer composition of the following composition, wt. %:

acetone-formaldehyde resin 80.0 sodium carbonate or potassium 4.0-7.0 oxyl-SM 0.5 water or 30% aqueous solution sodium chloride NaCl rest

Moreover, for formation temperatures of 50 ° C and below, an alkali — sodium hydroxide NaOH — in an amount of 0.1–2.5 wt. %, when conducting insulating work in a well with a high reservoir pressure, finely dispersed inert filler, technical talc, is additionally introduced into the specified material in an amount of 30-100% of the volume of the injected composition.

The disadvantages of this method are the high time and complexity of preparing the polymer composition for reservoir temperatures below 50 ° C, because it consists of 5 components, not counting the filler.

The closest in technical essence to the claimed proposal is a method of isolating and restricting water inflow into wells (Patent RU No. 2349731, IPC ЕВВ 33/13, С09K 8/512, publ. March 20, 2009, bull. No. 8), including injection into well insulation composition containing formaldehyde resin and a curing initiator in the following ratio of components, wt. %:

urea-formaldehyde or acetone formaldehyde resin 20.0-70.0 ethoxylated isononylphenols, ethoxylated monoalkylphenols or a mixture thereof 0.5-4.0 natural or synthetic rubber or a mixture thereof 0.05-50.0 polymerization initiator 0.5-3.0 water rest

As polymerization initiators for resins, for example, carboxylic acids and their salts can be used - alkaline stockpile of caprolactam production (SCHPC). The insulation composition may also contain various fillers.

The disadvantages of the closest analogue are:

- the complexity of the preparation of the polymer composition, because it consists of 5 components, excluding fillers;

- pumping in cycles, and squeezing fluid is pumped after each cycle, which complicates the process of conducting work on the well;

- the inability to create a waterproofing screen with a large radius due to the low filterability of the composition, which adversely affects the quality of insulation and reduces the effectiveness of the method.

The technical objectives of the proposal are to increase the efficiency of the RIR method by increasing the radius of the waterproofing screen and increasing the coverage of exposure, extending the gelation time interval, as well as reducing the duration and complexity of the work.

Technical problems are solved by the method of repair and insulation works in the well, including the preparation and injection into the well of a water-proofing composition containing acetone-formaldehyde resin, alkaline runoff of caprolactam production and 10% sodium hydroxide solution.

What is new is that to prepare a water-proofing composition, the alkaline stock of caprolactam production is mixed with a 10% sodium hydroxide solution and added to the acetone-formaldehyde resin with stirring, the resulting water-proofing composition is pumped into the well, after which it is left for gelation for 24-48 hours at the following content of components, wt. %:

acetone formaldehyde resin 20,0-40,0 caprolactam production alkaline stock 45.0-60.0 10% sodium hydroxide solution 15.0-20.0

Components used in the proposal:

- acetone-formaldehyde resin (ACP), obtained by condensation of acetone with formaldehyde, is a light to brown water-soluble homogeneous liquid with a mass fraction of solids of not less than 75%, with a mass fraction of free formaldehyde of not more than 1.5%, with a density of not less than 1200 kg / m ³ ;

- ShchSPK is a waste product of caprolactam production; it is a brown to dark brown liquid, opaque, without mechanical impurities. The mass fraction of sodium salts of organic acids (in terms of sodium adipate) is from 18 to 36%, the pH is in the range of 10-13;

- sodium hydroxide (NaOH) according to GOST R 55064-1012. Technical caustic soda. Technical conditions

The essence of the proposal is as follows. The injectivity of the isolated interval is determined in the well, and a water-proofing composition is prepared in advance using standard techniques for well overhaul. To do this, SHCHPK is mixed with a 10% solution of NaOH, then the resulting solution is mixed with ACF until a homogeneous mass is obtained, after which the water-proofing composition is pumped into the well, taking into account that a bridge with a height of at least 20 m is left in the well and left for a technological pause (gel ) within 24-48 hours

Water inflow in the well is limited due to the formation of a water-proof screen made of polymer gel based on ACP in the water inflow zone. The initiators of the gelation of the composition are a 10% solution of NaOH and alkali hydrogen sulfide, and, changing their amount in the composition, they regulate the gelation time over a wide range. The joint use of a 10% solution of NaOH and alkali sulfate complex decreases the viscosity of the water-insulating composition and increases its gelation time. The method allows injection to be carried out even in low-permeable layers, and an extended waterproofing screen is formed, which does not collapse under formation conditions. An additional contribution to the hardening of the waterproofing screen is made by the mineralized formation water, which interacts with the salts of organic acids contained in alkali-ferrous alloys, which increases the efficiency of the method. During a technological pause for 24-48 hours, due to an increase in the viscosity of the waterproofing composition, the process of blocking the highly permeable part of the formation and hardening the waterproofing screen is completed, which helps to reduce the influx of water.

The cost of the waterproofing composition is reduced by 2 times due to the fact that, unlike the closest method, it contains more SCHSPK (45-60 wt.%), Which is a waste product and has a low cost (4 thousand rubles per 1 ton ) Due to the fact that the waterproofing composition consists of only 3 components (more than 5 components of the known method and the closest analogue), the duration and complexity of the work are reduced.

In laboratory conditions, a waterproofing composition is prepared as follows. In a beaker with a volume of 100 ml, 40 ml of SCHPSC (40 wt.%) And 20 ml of a 10% solution of NaOH (20 wt.%) Are poured and mixed. The resulting solution was mixed with 40 ml of ACP (40 wt.%). The time of the beginning of the experiment and the loss of fluidity of the composition is noted, the difference between which is considered the time of its gelation. In this experiment No. 8, it amounted to 4 hours 10 minutes. The gelation results are presented in the table.

To compare the duration of gelation, the table shows the compositions of the insulation composition according to the closest analogue containing ADC, with the longest structuring time - 5 hours 15 minutes (No. 9 ⁴ ) and the shortest structuring time - 1 hour 55 minutes (No. 7 ³ ). The compositions of the waterproofing composition of the proposed method in terms of gelation duration (from 4 hours 10 minutes to 8 hours) are superior to the compositions according to the closest analogue.

By changing the ratio of the components, the gelation time of the waterproofing composition can be adjusted within 4-8 hours. Experiments Nos. 9 and 10 are excluded from the claimed range, since the gelation time of the waterproofing composition does not provide the optimal injection time into the well - more than 4 hours. Experiments No. 1 and 11 are excluded from the claimed range, since gelation does not occur. Based on the test results, compositions were selected that were included in the claimed range of component ratios, wt. %:

acetone formaldehyde resin 20,0-40,0 caprolactam production alkaline stock 45.0-60.0 10% sodium hydroxide solution 15.0-20.0

The implementation of the proposed method is represented by examples.

Practical examples

Example 1. Sealing the production casing

The method was carried out in a well with a casing string with a diameter of 168 mm, perforation intervals of 987-989 m and violation of the integrity of the production string 345 m. The specific injectivity of the disturbance interval was 1.4 m ³ / (h (MPa). We cut off the perforation interval by sanding and installing a cement bridge on top. A string of tubing with a nominal diameter of 73 mm was lowered into a well to a depth of 315 m. The preparation of the waterproofing composition was carried out using a cementing unit CA-320M. In the first half of the unit’s measuring unit, 1.6 m ³ (40 wt.%) Of alkali carbon dioxide and 0.8 m ³ (20 wt.%) Of a 10% NaOH solution were pumped. 1.6 m ³ (40 wt.%) ACP was pumped into the second half of the unit’s meter, the contents of both halves of the unit’s meter were mixed for 10 min and the water-proofing composition was pumped through the tubing into the well, after which 0.95 m of technical water was pumped from the tubing the purpose of forcing the waterproofing composition into the violation interval. We carried out a control flushing of the tubing string, raising the tubing string to a depth of 165 m and left the well for gelation of the waterproofing composition for 24 hours. We drilled a bridge, washed the sand and carried out a control flushing of the well with the tubing string running down to the bottom. Then they mastered the well, lowered the underground equipment and put the well into operation. As a result of the work, the water cut of the well’s production decreased by 52%, the oil production rate increased 1.9 times.

Example 2. Insulation of interstratal flow along cracks

The method was carried out in a well with a casing string of 146 mm in diameter, the perforation interval in the well was 1674-1678 m. A tubing with a nominal diameter of 73 mm was lowered into the well to a depth of 1644 m. The injectivity of the well was determined, which amounted to 2.1 m ³ / (h⋅MPa). The preparation of the waterproofing composition was carried out using a cementing unit CA-320M. In the first half of the unit’s measuring unit, 3.6 m ³ (60 wt.%) Of alkali carbon dioxide and 1.2 m ³ (20 wt.%) Of a 10% NaOH solution were pumped. 1.2 m ³ (20 wt.%) ACP was pumped into the second half of the unit’s measuring unit. Then, the contents of both halves of the unit’s measuring unit were mixed for 10 min and pumped into the well, after which 7.0 m ^{3 of} process water was pumped with the aim of reselling the waterproofing composition in the interval of well perforation. They left the well for gelation for 48 hours. Next, they carried out a control flushing of the well from possible residues of the polymerization products of the waterproofing composition with the tubing string down to the bottom, mastered the well, lowered the underground equipment and put the well into operation. As a result of the work, the water cut of the well production decreased by 27%, the oil production rate increased 1.9 times.

Example 3. The elimination of annular flow

The method was carried out in a well with a casing 114 mm in diameter, a perforation interval of 1459-1465 m and a casing flow from a depth of 1478 m. Perforation of special technological holes was carried out in the range of 1469-1470 m. The specific injectivity of special holes was 1.2 m ³ / (h ⋅MPa), there was no message between the perforation interval and the special holes. A packer-retainer was lowered into a well on a tubing string with a nominal diameter of 60 mm and planted at a depth of 1473 m. The insulation composition was prepared using a cementing unit CA-320M. In the first half of the unit’s measuring unit, 2.0 m ³ (50 wt.%) Of alkali carbon dioxide and 0.8 m ³ (20 wt.%) Of a 10% NaOH solution were pumped. 1.2 m ³ (30 wt.%) ACP was pumped into the second half of the unit’s measuring unit. Next, the contents of both halves of the unit’s measuring unit were mixed for 10 min and pumped through the tubing string into the well, after which 2.8 m ^{3 of} sewage was pumped to squeeze the composition. The landing gear was removed from the packer, a control flushing was carried out, and the tubing string with the landing gear was lifted out of the well completely. They left the well for gelation for 36 hours. Next, they carried out a control flushing of the well with the launch of the tubing string to the bottom, mastered the well, lowered the underground equipment and put the well into operation. As a result of the work, the water cut of the well’s production decreased by 59%, the oil production rate increased 1.7 times.

Thus, in the proposed proposal, the result was achieved - increasing the effectiveness of the RIR method by increasing the radius of the water barrier screen and increasing the coverage of exposure, extending the gelation time interval, as well as reducing the duration and complexity of the work.

Claims (2)

The method of repair and insulation work in the well, including the preparation and injection into the well of a waterproofing composition containing acetone-formaldehyde resin, an alkaline stock of caprolactam production and a 10% sodium hydroxide solution, characterized in that for the preparation of a waterproofing composition, an alkaline stock of caprolactam production is mixed with 10% solution of sodium hydroxide and added with stirring to acetone-formaldehyde resin, the resulting waterproofing composition is pumped into the well, after which o leave it at the time of gelation for 24-48 hours with the following components, wt. %: acetone formaldehyde resin 20,0-40,0 caprolactam production alkaline stock 45.0-60.0 10% sodium hydroxide solution 15.0-20.0.