RU2494225C1 - Method for limiting water influx in well - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method for limiting water influx in a well involves portion pumping to the isolation interval of composition and gel-forming regulator. Composition contains hydrolysed polyacrylonitrile - 100 parts by volume, liquid glass - 20-50 parts by volume, polyacrylamide DP9-8177 - 50-100 parts by volume. Aluminium oxychloride in the amount of 200-300 parts by volume is used as gel-forming regulator.

EFFECT: improving efficiency of waterproofing work owing to increasing the coverage range due to formation of polymer mass immediately at the isolation interval, as well as simplifying the method and its operability in fresh waters.

Description

The proposal relates to the oil industry, in particular, to methods for limiting water inflow into the well using hydrolyzed polyacrylonitrile (hypane), and can be used to limit the flow of water into the reservoir, shut off the reservoirs and eliminate annulus flows in production wells.

A known composition for the isolation of water in wells (US Pat. RU No. 1329240, IPC ЕВВ 33/138, publ. 08/09/1995, bull. No. 22), which contains gipan, sodium silicate and water. The composition is intended to limit water inflow in weakly mineralized and highly permeable reservoirs. When the composition enters the flooded formation and mixes it with formation water containing metal ions (calcium, magnesium, etc.), hypane and sodium silicate are precipitated with the formation of a granular-gel mass capable of blocking pores and small cracks. A disadvantage of the known composition is that it forms a gel only in the presence of metal ions, i.e. in mineralized formation water.

Known polymer grouting composition for mounting oil and gas wells (US Pat. RU No. 2180037, IPC ЕВВ 33/138, publ. 02.27.2002, bull. No. 6). The composition contains an aqueous solution of hypane, water and an additive, as an additive it contains cross-linked polyacrylamide AK-639 in the following ratio of components, parts by weight: hypane - 100, cross-linked polyacrylamide AK-639 - 2-3, water - 100.

A disadvantage of the known composition is that it is unsuitable for limiting freshwater inflow. A rim of 5% calcium chloride solution must first be pumped into the well.

Closest to the technical nature of the claimed is a method of isolating formations, including the injection of a visco-plastic material for isolating formations (A.S. No. 1416669, IPC Е21В 38/138, publ. 08/05/1988, bull. No. 30), which when injected into the well forms a plugging gel in the formation. The composition contains hypane, water, water glass, an inert additive and, as a gelation regulator, hydrochloric acid (HCI) in the following ratio, wt.%:

hypane 1.0-3.0 liquid glass 7.0-10.0 hydrochloric acid (HCI) 0.3-0.7 inert filler 5.0-10.0 water swellable additive 0.5-1.0 water rest.

As an additive that swells in water, the material contains powdered carboxymethyl cellulose or condensed sulphite-alcohol vinasse, or a carbon-alkaline reagent.

Visco-plastic material can be obtained in two ways.

I. An inert filler is dispersed in water, then gipan and water glass are added, the mixture is stirred until homogeneous. Hydrochloric acid and a water-swellable additive are successively introduced into the resulting mixture.

II. Viscoplastic material is prepared in two stages. Equal volumes of two solutions are preliminarily prepared:

1) at half the calculated amount of water injected _^half portion of an inert filler, hydrolyzed polyacrylonitrile, _^1/2 part of hydrochloric acid;

2) the remaining part of the inert filler and hydrochloric acid, liquid glass and the additive swelling in water are introduced into the other half of the water.

The solutions prepared according to method II are pumped simultaneously through tubing and annulus.

The disadvantages of this method are the multicomponent composition and the short gel formation time for any method of preparation, as a result of which it remains close to the wellbore and can be washed out of it over time.

The technical task of the proposal is to increase the effectiveness of waterproofing works by increasing the coverage of the impact due to the formation of polymer mass directly in the isolation interval, as well as simplifying the method and its performance in fresh waters.

The problem is solved by the proposed method of limiting water inflow into the well, including injection into the isolation interval of the composition and gelation regulator.

New is that the injection of the composition and the gelation regulator is carried out sequentially in portions, while the composition contains gipan, water glass, DP9-8177 polyacrylamide, and aluminum oxychloride is used as the gelation regulator in the following ratio of components, parts by volume:

hypane one hundred liquid glass 20-50 polyacrylamide DP9-8177 50-100 aluminum oxychloride 200-300.

A new set of claimed essential features allows to obtain a new technical result: an effective way to limit water inflow into the well.

The reagents used in the present method are presented in table 1.

Table 1 Reagent concentration or density Reagent Name Name GOST or TU The appearance of the reagent HSV reagent (dry gipan) or TU 2458-005-58949915-2004 yellow powder or lumps; orange tint allowed; yellow to dark brown viscous liquid 6-10% aqueous solution Gipan TU 6-01-166-89 Liquid sodium glass (liquid glass) GOST 13078-81 thick yellow or gray liquid without mechanical impurities and inclusions visible to the naked eye density 1360-1450 kg / m ³ Polyacrylamide DP9-8177 TU 2458-010-70896713-2006 white to cream powder 0.1-0.05% aqueous solution Aluminum oxychloride TU 2471-077-05766563-2006 slightly yellow or gray liquid with a greenish tint 15-25% aqueous solution

The essence of the proposal is that through the tubing, lowered into the interval of insulation work, sequentially in portions into the interval of isolation pump the composition and the gelation regulator. In order to prevent premature gelation between portions of the composition and the gelation regulator, a buffer of fresh water is pumped in a volume of 200-300 l. When the composition and the gelation regulator contact in the isolation interval, a polymer mass is formed that blocks the flow of water into the flooded layer of the well. Solutions of the reagents included in the composition are prepared before injection: a 6-10% solution of gipan is prepared from marketed gipan (10-15% solution) or from HSV reagent (dry gipan) by adding the calculated amount of fresh water with a density of 1000 to them kg / m ³ and further mechanical mixing; A 0.1-0.05% aqueous solution of DP9-8177 polyacrylamide is prepared similarly.

Before injection into the well, the composition is mixed for 20-30 minutes in an averaging tank or in a tank truck with a reagent ratio of 100 vol. including gipan, 20-50 vol. including liquid glass and 50-100 vol. including polyacrylamide DP9-8177. The resulting composition and the gelation regulator are injected into the flooded layer of an oil producing well in several portions (the number of portions of the gelation composition and regulator is equal to from two to three). Portions of the composition of the composition are injected with portions of a gelation regulator - a solution of aluminum oxychloride, so that its total volume is 2-3 times higher than the volume of hypane, and between portions of the composition and a gelation controller, a buffer of fresh water is pumped in a volume of 200-300 l to prevent premature gelation. When the composition and the gelation regulator are injected sequentially in several portions, they are better mixed in the pore space than when the entire volume of the composition and the gelation regulator is injected in one step and allows them to penetrate deep into the pores and fractures of the formation, which ensures blocking of highly permeable and then low permeability pores of the formation . The presence of liquid glass in the composition strengthens the polymer structure obtained from hypane and polyacrylamide DP9-8177, and the latter improves the adhesion of the composition to the formation rock. Aluminum oxychloride serves as a regulator of the gel formation of the composition - the dense polymer mass formed by it is resistant to formation fluids, fresh water and better insulating ability than the viscoplastic material obtained by the action of hydrochloric acid - the gel formation regulator of the closest analogue. At high reservoir pressures, after injecting the composition and aluminum oxychloride, cement slurry is pumped into the well in order to fix the polymer mass formed by the composition and aluminum oxychloride and prevent it from leaving the isolation zone.

In laboratory conditions, the method is as follows. 100 parts by volume are poured into a glass cup. (100 ml) of an 8% solution of hypane, 20 vol.h. (20 ml) of liquid glass with a density of 1420 kg / m ³ , 50 vol. including (50 ml) of a 0.05% solution of DP9-8177 polyacrylamide, stirred for 1 minute until a homogeneous solution is formed.

The prepared composition and gelation regulator are divided into two portions (in the case of injection of the composition and gelation regulator into three portions, each of them is divided into three portions). To 100 vol.h. (100 ml) of a 20% solution of aluminum oxychloride pour one portion of the obtained composition, 100 vol.h. (100 ml) of a 20% solution of aluminum oxychloride, a second portion of the composition (example 2, table 2), a volume gel is formed.

Testing the water-insulating ability of the proposed method is carried out on reservoir models with a length of 30 cm and an inner diameter of 2.7 cm filled with quartz sand fraction 0.2-0.3 mm, which allow you to simulate the injection of the composition into the reservoir and to continuously monitor its flow rate according to the scheme: “Well-formation” and “formation-well”. Initially, water with a density of 1000 kg / m ³ and mineralization of 0.5 g / l is pumped through a reservoir model filled with quartz sand, its flow rate is measured, and the initial permeability of the model is determined by the Darcy formula.

The composition is prepared as follows: mix solutions of hypane, water glass, polyacrylamide DP9-8177 in the following ratio: 100 vol. including gipan, 20-50 vol. including liquid glass and 50-100 vol. including polyacrylamide DP9-8177. The resulting composition is divided into two (three) equal portions, 200-300 vol. including aluminum oxychloride is also divided into two (three) equal portions. Next, the first portion of the composition is pumped through the model, a buffer of water with a density of 1000 kg / m ³ and a salinity of 0.5 g / l, a first portion of aluminum oxychloride, a buffer of water with a density of 1000 kg / m ³ and a salinity of 0.5 g / l, the second a portion of the composition, a buffer of water with a density of 1000 kg / m ³ and mineralization of 0.5 g / l, a second portion of aluminum oxychloride. The model is left for 24-36 hours for the purpose of gelation. After that, water is pumped with a density of 1000 kg / m ³ and mineralization of 0.5 g / l, the permeability is determined by the Darcy formula and the insulation coefficient is calculated, which characterizes the degree of clogging of the pores, the decrease in the permeability of the model, and is a measure of the effectiveness of the insulation work.

To compare the effectiveness of the proposal, we tested it and the closest analogue. The results of the study of water-insulating ability are given in table.2.

table 2 The results of the study of the waterproofing ability of the proposed method and the closest analogue No. The components of the proposed composition, about. hours Servings Per Container * The gelation regulator is aluminum oxychloride, vol. hours The insulation coefficient of the compounds after 24 hours,% The insulation coefficient of the compounds after 6 months.,% Gipan Polyacryl amide DP9-8177 Liquid glass one one hundred thirty one hundred 2 fifty 82.5 76.6 2 one hundred fifty twenty 2 200 99.6 98.8 3 one hundred 75 40 2 200 99.8 98.6 four one hundred one hundred fifty 3 300 96.8 95.7 5 one hundred 75 thirty 3 300 98.5 96.8 6 one hundred 125 fifteen 3 150 85,4 78.8 The closest analogues ** 90.3-95.5 72-78 Note: * The number of servings of the composition and gelation regulator ** Reproduced by the applicant

Compounds No. 1 and 6 have a low insulation coefficient, so they were excluded from the claimed range. Optimum are the compositions (No. 2-5), which are included in the claimed range of the ratio of components, ob.ch .:

hypane one hundred liquid glass 20-50 polyacrylamide DP9-8177 50-100 aluminum oxychloride 200-300.

As can be seen from the results of Table 2, the insulation coefficient after 6 months of the proposed method is higher than that of the closest analogue by 21-25.6%, and the use of fresh water with a salinity of 0.5 g / l does not reduce the effectiveness of the method. Thus, the proposed method provides an increase in exposure coverage due to the formation of a polymer mass directly in the isolation interval, and the creation of a strong gel, the simplification and operability of the method in fresh waters, ultimately contribute to an increase in the efficiency of waterproofing works.

Claims (1)

A method of limiting water inflow into a well, comprising injecting a gelling agent and a gelling regulator into the isolation interval, characterized in that the gaseous composition and gelling agent are injected sequentially in portions, the composition containing gipan, water glass, DP9-8177 polyacrylamide, and oxychloride is used as a gelling regulator aluminum in the following ratio of components, ob.ch .:
hypane one hundred liquid glass 20-50 polyacrylamide DP9-8177 50-100 aluminum oxychloride 200-300