Method for performing remedial sealing operations in oil and gas wells

Abstract

A method for performing remedial sealing operations in oil and gas wells includes feeding a sealing composition under pump pressure into a well annulus having an annular pressure. Said sealing composition contains an aqueous solution of a weighting material, and a polymer resin. First, the aqueous solution of weighting material is injected, wherein powdered weighting material, more specifically a powder of an alkali metal having a specific density of 1.5-1.7 g / cm3, is pre-mixed with water in an amount of 50-100 wt.% of the amount of powdered weighting material. Then the polymer resin is injected in an amount of 5-10 wt.% of the amount of the aqueous solution of weighting material. The polymer resin is a phenol-resorcinol-formaldehyde resin, an epichlorohydrin resin or a diglycidyl resin. The alkali metal powder is a powder of water-soluble sodium, water-soluble potassium or water-soluble lithium. The result is an improvement in well performance at temperatures down to -50°С.

Description

[0001] Method of carrying out repair and insulation works of oil and gas wells

[0002] The invention relates to the oil and gas production industry, in particular to repair and insulation work in oil and gas wells, carried out during routine and major repairs of the well to eliminate behind-the-casing gas and / or fluid flows, limit water inflows, isolate aquifers and increase the efficiency of well operation at temperatures down to - 50° C.

[0003] A method is known for treating the bottomhole zone of a formation, which includes injecting a rim of oil-soluble solvent into the formation; before injecting the rim of oil-soluble low-molecular solvent into the formation, a water-soluble low-molecular solvent is injected into the formation, and the oil rim is injected into the formation after the rim of oil-soluble low-molecular solvent is injected, with the ratio of the volumes of the rims of water-soluble and oil-soluble low-molecular solvents and oil being 0.35:0.1:0.55 (RU Patent No. 2176020, E21B 43 / 22; published on 20.11.2001).

[0004] The disadvantages of the known Method are: the injection solution in this method has a low density, which complicates injection into the treatment zone, and solvents also have the property of aggressively affecting equipment elements, including rubber seals of the Christmas tree fittings and casing columns. The closest is the Method of carrying out repair and insulation work in an oil and gas well, characterized by the fact that an aqueous solution of calcium chloride with a concentration of 10-12% and an aqueous solution of sodium sulfate with a concentration of 13-15% are injected behind the casing column at a pressure not exceeding 70% of the permissible internal pressure on the casing pipes, the well is kept at rest for 15-30 minutes until the formation of the Ca80 sediment is complete.and then an aqueous solution of polyacrylamide with a concentration of 0.5-3% is pumped in to create the effect of strengthening the isolated interval at the same pressure value, followed by holding the well for 2-7 hours until the gelation process is complete (RU Patent No. 2723416, E21B 33 / 138; 43 / 22; 43 / 32; C09K 8 / 504, C09K 8 / 508, published 11.06.20, prototype).

[0005] The disadvantages of the known method are the precipitation of the SaBO reagent, which reduces the effectiveness of the solution when carrying out repair and insulation work in the well.

[0006] The technical result of the claimed Method consists in increasing the efficiency of repair and insulation work in a well at temperatures down to - 50° C by ensuring the sealing of channels - cracks in the well from which fluid and / or gas emerges into the well and forms inter-column pressure (ICP), which, through the complete and uniform spreading of a composition with high permeability, eliminates the inter-column pressure in the inter-column space.

[0007] The set result is achieved by the fact that the Method of carrying out repair and insulation work on oil and gas wells, including feeding an insulating composition under injection pressure into the annular space of a well with an annular pressure, wherein the insulating composition contains an aqueous solution of a weighting additive and a polymer resin, which are pumped in sequentially, and an alkali metal powder with a specific density of 1.5 g / cm is used as a weighting additive. 3 up to 1.7 g / cm 3, whereby first an aqueous solution of the weighting additive is pumped in, after having previously mixed the weighting additive powder with water taken in an amount of 50 to 100 mass % of the calculated amount of weighting additive powder with a specific density of 1.5 g / cm 3 up to 1.7 g / cm 3 , then a polymer resin is pumped in, taken in an amount of 5 to 10 mass % of the calculated amount of an aqueous solution of a weighting additive, phenol-resorcinol-formaldehyde resin or epichlorohydrin resin, or diglycidyl resin are used as the polymer resin, and water-soluble sodium powder or water-soluble potassium powder, or water-soluble lithium powder are used as the alkali metal powder. The method for carrying out repair and insulation work on oil and gas wells is carried out as follows.

[0008] The insulating composition is supplied under injection pressure, ensuring that the insulating composition enters the interval of well leakage in the form of cracks, channels, crevices, etc., from which fluid and / or gas emerges into the annular space of the well with annular pressure by known means and known methods.

[0009] The insulating composition contains an aqueous solution of a low-rheology weighting additive and a polymer resin, which are pumped sequentially into the well leak interval.

[0010] The aqueous solution of the weighting additive consists of two components: water and alkali metal powder with low rheology (fluidity) with a specific density of 1.5 g / cm 3 up to 1.7 g / cm 3, providing well parameters that allow the creation of a hydrostatic barrier for gas and / or fluid from a leaky interval in the cemented annular space of the well, for example, the density of liquids present in the well.

[0011] An aqueous solution of a weighting additive is prepared by dissolving a weighting additive powder with low rheology (flowability) at a specific density of 1.5 g / cm 3 up to 1.7 g / cm 3 additives in water, for example, in fresh water, by known means and known methods, wherein water is taken in an amount of 50 to 100 mass. % of the calculated amount of powder of the weighting additive.

[0012] The resulting aqueous solution of the weighting additive is pumped at an injection pressure of 10 atm to the maximum permissible pressure, which is determined based on the parameters of the wellhead equipment, inter-packer seals and casing strings, etc.

[0013] As a weighting additive with low rheology (flowability) at a specific density of 1.5 g / cm 3 up to 1.7 g / cm 3 use alkali metal powder, for example, fine-crystalline powder of water-soluble sodium according to GOST 3273-75, for example, water-soluble sodium polyacrylate PAAS powder of water-soluble potassium according to GOST 4568-95, for example, potassium sulfate, fine-crystalline powder of water-soluble lithium according to GOST 8774-75, for example, lithium molybdate. Weighting additive with a specific density of 1.5 g / cm 3 up to 1.7 g / cm 3 provides low fluidity to the main component of the insulating composition - polymer resin, allowing it to be applied evenly to the surface being treated and increasing the efficiency of sealing cracks, etc.

[0014] Then, under injection pressure, a polymer resin is pumped into the leaky interval - into the annular space of the well with annular pressure using known means and known methods, for example, phenol-resorcinol-formaldehyde resin; epichlorohydrin resin; diglycidyl resin.

[0015] The polymer resin is injected in an amount of 5 to 10 mass % of the calculated amount of the aqueous solution of the weighting additive at an injection pressure of 10 atm to the maximum permissible pressure, which depends on the parameters of the wellhead equipment, interpacker seals and casing strings.

[0016] For example, polymer resins are used:

[0017] - phenol-resorcinol-formaldehyde resin according to TU 20.59.59-001-19983784-2019, for example, resin RSF-014 290, resin brand IDT-Resin;

[0018] - epichlorohydrin resin according to GOST 12844-74, for example, polyamide epichlorohydrin resin, VitaChem brand resin;

[0019] - diglycidyl resin according to GOST 12138-86, for example, bisphenol diglycidyl ether resin; DER 332 RESINS; EPON (R) RESIN 828; 2.2'; Bisphenol A resin.

[0020] At an injection pressure below 10 atm, the efficiency of repair and insulation work in the well is reduced due to the difficulty of pumping the components of the insulating composition into the treatment zone - into the interval of well leakage, while the calculated amount of powder of the weighting additive and the aqueous solution of the weighting additive is determined depending on the characteristics of the well, including the characteristics of cracks, channels, crevices, etc., from which fluid and / or gas appears in the annular space of the well, and the choice of a specific technology for pumping the components of the insulating composition is determined based on the set goal of repair and insulation work in the well.

[0021] By pumping an aqueous solution of a weighting additive and then pumping a polymer resin at their stated quantitative values, namely, water is taken in an amount of 50 to 100 mass. % of the calculated amount of weighting additive powder at a specific density of 1.5 g / cm 3 up to 1.7 g / cm 3 to obtain an aqueous solution of a weighting additive, and the polymer resin is taken in an amount of 5 to 10 mass. % of the calculated amount of an aqueous solution of a weighting additive, ensuring complete and uniform spreading of the insulating composition, which has high permeability, allowing the elimination of intercolumn pressure in the intercolumn space.

[0022] Changing the order of pumping the components of the insulating composition, decreasing or increasing their declared quantitative values ​​and decreasing or increasing the specific density of the weighting additive reduces the efficiency of the insulating composition during repair and insulation work in a well at temperatures down to - 50° C, without ensuring the plugging of cracks, channels - crevices in the well and without eliminating the inter-column pressure in the inter-column space. The proposed Method was tested under field conditions in wells in the Russian Federation, including wells in the Yamal-Nenets Autonomous Okrug of the Purovsky District, and a positive result was obtained from the work performed.

[0023] Example 1.

[0024] In well No. 7027 of the Severo-Gubkinskoye field, repair and insulation work was carried out during routine repairs of the well to eliminate behind-the-casing gas flows at a temperature of -30° C.

[0025] After which, the insulating composition was supplied under an injection pressure of 30 atm to 200 atm, ensuring that the insulating composition entered the interval of well leaks in the form of cracks, channels, crevices, etc., from which fluid and / or gas emerges into the annular space of the well with an annular pressure of 35 atm by known means and known methods.

[0026] The insulating composition contained an aqueous solution of a weighting additive, in which the weighting additive was taken in the form of a water-soluble powder of sodium polyacrylate PAAS with a specific density of 1.5 g / cm 3 up to 1.7 g / cm 3 and a polymer resin in the form of epichlorohydrin resin.

[0027] The injection of an aqueous solution of sodium polyacrylate PAAS and epichlorohydrin resin was carried out sequentially at an injection pressure of 50 atm.

[0028] First, the calculated amount of the prepared aqueous solution of sodium polyacrylate PAAS, obtained by mixing water-soluble sodium polyacrylate PAAS powder with a specific density of 1.5 g / cm, was injected. 3 up to 1.7 g / cm 3 , taken in the amount of 1000 kg, in water taken in the amount of 500 l, which was 50 wt.% of 1000 kg of sodium polyacrylate powder PAAS with a specific density of 1.5 g / cm 3 up to 1.7 g / cm 3 Then, 50 l of epichlorohydrin resin was injected, which was 5 to 10 wt. % of the calculated amount of aqueous sodium polyacrylate PAAS solution, at an injection pressure of 50 atm.

[0029] The quantitative ratio of the aqueous solution of sodium polyacrylate PAAS and epichlorohydrin resin was determined based on the characteristics of well No. 7027 and the conditions of well No. 7027 after repair and insulation works (including the characteristics of the leakage of the annular space of well No. 7027), and the choice of a specific technology for pumping components was carried out depending on the set goal of the repair and insulation works in the well: elimination of behind-the-casing gas flows.

[0030] As a result of carrying out repair and insulation works in the declared manner, inter-column pressure in the inter-column space was eliminated by means of plugging the channels - cracks in the well from which gas emerged, forming inter-column pressure (ICP) - with an insulating composition, and behind-the-casing gas flows were eliminated by means of complete and uniform spreading of the insulating composition, which also has high permeability, increasing the efficiency of repair and insulation works in the well at temperatures up to - 50° C.

[0031] Example 2.

[0032] In well No. 7022 of the Severo-Gubkinskoye field, repair and insulation work was carried out during routine repairs of the well to limit water inflows at a temperature of -35° C.

[0033] After which, an insulating composition containing an aqueous solution of a weighting additive, in which the weighting additive is taken in the form of lithium molybdate powder with a specific density of 1.5 g / cm, was fed under pressure from 30 to 100 atm into the annular space of the well with an annular pressure of 38 atm. 3 up to 1.7 g / cm 3 , and a polymer resin in the form of diglycidyl resin.

[0034] The injection of an aqueous solution of lithium molybdate and diglycidyl resin was carried out sequentially at an injection pressure of 45 atm.

[0035] First, the calculated amount of the prepared aqueous solution of lithium molybdate, obtained by mixing water-soluble lithium molybdate powder with a specific density of 1.5 g / cm, was pumped in. 3 up to 1.7 g / cm 3 , taken in the amount of 1000 kg, in water taken in the amount of 1000 l, which was 100 mass. % of 1000 kg of water-soluble lithium molybdate powder with a specific density of 1.5 g / cm 3 up to 1.7 g / cm 3 .

[0036] Then, 100 l of diglycidyl resin was injected, which was 5 to 10 wt. % of the calculated amount of lithium molybdate aqueous solution, at an injection pressure of 50 atm.

[0037] The quantitative ratio of the aqueous solution of lithium molybdate and epichlorohydrin resin was determined depending on the characteristics of well No. 7022 and the conditions of well No. 7022 after repair and insulation works (including the characteristics of the leakage of the annular space of well No. 7022), and the choice depending on the characteristics of well No. 7022, and the choice of a specific technology for pumping components was carried out depending on the set goal of repair and insulation works in the well: limiting water inflows.

[0038] As a result, the inter-column pressure in the inter-column space was eliminated, ensuring the blockage of channels - cracks in the well from which gas was emerging, forming the inter-column pressure (ICP), and limited water inflows into the well by means of complete and uniform spreading of the composition with high permeability during the RIP, increasing the efficiency of RIP in the well at temperatures down to - 50° C.

[0039] Example 3.

[0040] In well No. 7017 of the Severo-Gubkinskoye field, repair and insulation work was carried out during routine repairs of the well to isolate aquifers at a temperature of -25° C.

[0041] After which, an insulating composition containing an aqueous solution of a weighting additive, in which the weighting additive is taken in the form of potassium sulfate powder with a specific density of 1.5 g / cm, was fed under pressure from 10 atm to 80 atm into the annular space of the well with an annular pressure of 5 atm. 3 up to 1.7 g / cm 3 , and a polymer resin in the form of phenol-resorcinol-formaldehyde resin of the IDT-Resin brand.

[0042] The injection of an aqueous solution of potassium sulfate and phenol-resorcinol-formaldehyde resin of the IDT-Resin brand was carried out sequentially at an injection pressure of 45 atm,

[0043] First, the calculated amount of the prepared aqueous solution of potassium sulfate was pumped in, obtained by mixing water-soluble potassium sulfate powder with a specific density of 1.5 g / cm 3 up to 1.7 g / cm 3 , taken in the amount of 1000 kg, in water taken in the amount of 750 l, which was 75 mass. % of 1000 kg of water-soluble potassium sulfate powder with a specific density of 1.5 g / cm 3 up to 1.7 g / cm 3 .

[0044] Then, 50 l of IDT-Resin phenol-resorcinol-formaldehyde resin was injected, which was 5 to 10 wt. % of the calculated amount of potassium sulfate aqueous solution, at an injection pressure of 50 atm.

[0045] The quantitative ratio of the aqueous solution of potassium sulfate and epichlorohydrin resin was determined depending on the characteristics of well No. 7017 and the conditions of well No. 7017 after repair and insulation work (including the characteristics of the leakage of the annular space of well No. 7017), and the choice of a specific technology for pumping components was carried out depending on the set goal of repair and insulation work in the well: isolation of aquifers.

[0046] As a result, the inter-column pressure in the inter-column space was eliminated, ensuring the blockage of channels - cracks in the well from which gas was emerging, forming the inter-column pressure (ICP), and limited water inflows into the well by means of complete and uniform spreading of the composition with high permeability during the RIP, increasing the efficiency of RIP in the well at temperatures down to - 50° C.

[0047] The claimed Method increases the efficiency of repair and insulation work in a well at temperatures down to - 50° C, ensuring the plugging of channels - cracks in the interval of leakage of the well, from which fluid and / or gas emerges into the well, by means of complete and uniform spreading of the components of the insulating composition, which has high permeability, thereby eliminating inter-column pressure in the inter-column space and eliminating behind-the-column flows of gas and / or fluids, limiting water inflows and isolating aquifers.

Claims

Formula 1. A method for carrying out repair and insulation work on oil and gas wells, including feeding an insulating composition under injection pressure into the annular space of a well with an annular pressure, characterized in that the insulating composition contains an aqueous solution of a weighting additive and a polymer resin, which are pumped in sequentially, and an alkali metal powder with a specific density of 1.5 g / cm is used as a weighting additive. 3 up to 1.7 g / cm 3 , whereby first an aqueous solution of the weighting additive is pumped in, after having previously mixed the weighting additive powder with water taken in an amount of 50 to 100 mass% of the calculated amount of weighting additive powder with a specific density of 1.5 g / cm 3 up to 1.7 g / cm 3 , then the polymer resin is injected, taken in an amount of 5 to 10 mass% of the calculated amount of the aqueous solution of the weighting additive.

2. The method according to paragraph 1, characterized in that a phenol-resorcinol-formaldehyde resin is used as the polymer resin.

3. The method according to paragraph 1, characterized in that epichlorohydrin resin is used as the polymer resin.

4. The method according to paragraph 1, characterized in that diglycidyl resin is used as the polymer resin.

5. The method according to paragraph 1, characterized in that water-soluble sodium powder is used as the alkali metal powder.

6. The method according to paragraph 1, characterized in that water-soluble potassium powder is used as the alkali metal powder.

7. The method according to paragraph 1, characterized in that water-soluble lithium powder is used as the alkali metal powder.