The way of the development of oil deposits at a later stage

 

The invention relates to the oil and gas industry, in particular to methods of oil extraction from heterogeneous watered formations at a late stage of oil field development. The technical result - the creation of insulating screens with improved technological parameters and increase the duration of effect for areas of the reservoir with any permeability, as well as expansion of the range of chemical reagents in the process. In the way of the development of oil deposits at a later stage, including injection into the formation via the injection well an aqueous solution of reagents, forming an insoluble precipitate, as a reagent download metal chloride, the ratio of the injected reagents take in accordance with the stoichiometric coefficients, providing the greatest sediment yield, and production of oil through the production well, injection of aqueous solutions of reagents carried out sequentially or simultaneously, as the chloride of the metal used one component from the group of: calcium chloride, magnesium chloride, aluminum chloride, ferric chloride, as another reagent is a salt of polybasic acid or alkali, in addition, with a solution of salts of optionally centuries the ISR layer. To obtain a precipitate in the form of a metal hydroxide is used as the other reactant alkali as sodium hydroxide or potassium. As the use of water-repellent water-soluble organosilicon compound or anion surface-active substance with a concentration of 0.5-5%. 2 C.p. f-crystals, 2 tab.

The invention relates to the oil and gas industry, in particular to methods of oil extraction from heterogeneous watered formations at a late stage of oil field development.

There is a method of developing a flooded oil fields, the essence of which consists in injecting into the formation via the injection well an aqueous solution of aluminium chloride with subsequent injection of alkaline solution [1].

The disadvantage of this method is the short duration of effect, as during the subsequent injection of the displacing agent is blur and displacement of sediment.

The closest solution is used as a prototype, is a way to isolate the flow of formation waters, including sequential injection salts of polybasic acids and salts of alkaline-earth metals in the form of a solution or suspension [2].

The disadvantage of this method is the limitation of its application p is on the screen to blur.

Object of the invention is to provide a method for development of flooded oil fields in the late stage of operation by creating an insulating screens with improved technological options and increase the duration of effect for areas of the reservoir with any permeability, as well as expansion of the range of chemicals in the implementation of the proposed method.

The problem is solved in that in the method of development of oil deposits at a later stage, including injection into the formation via the injection well an aqueous solution of reagents, forming an insoluble precipitate, as a reagent download metal chloride, the ratio of the injected reagents take in accordance with the stoichiometric coefficients, providing the greatest sediment yield, and production of oil through the production well, according to the invention the injection of aqueous solutions of reagents carried out sequentially or simultaneously, as the chloride of the metal used one component from the group of: calcium chloride, magnesium chloride, aluminum chloride, ferric chloride, as another reactant is a salt of the polybasic acid or alkali, in addition, a solution of salts of optionally centuries the ISR layer.

To obtain a precipitate in the form of a metal hydroxide is used as the other reactant alkali as sodium hydroxide or potassium. As the use of water-repellent water-soluble organosilicon compound or anion surface-active substance with a concentration of 0.5-5%.

The essence of the invention lies in the fact that the reacting solutions of salts and alkalis take in such a ratio that provides the maximum sediment in the reservoir.

Table 1 presents examples of specific reactions with the accounting ratios of the reacting substances, according to the stoichiometric coefficients, providing the maximum yield of sediment. To the insulating screen cover layer more fully, as the capacity of the reservoir and along strike, you must apply the solutions with appropriate concentrations of reagents, and to protect the screen from erosion solutions must contain a hydrophobic reagent.

Hydrophobization of the screen is achieved by adding a water-repellent agent in solutions of metal chlorides. The water-repellent agent adsorbed on the surface of the rocks out hydrocarbon radical, in the breed and particles formed precipitate become hydrophobic, difficult to filter water is t, basically, anionic surfactants (alkylarylsulfonate, petroleum sulfonates, and so on ) or cationic substances (organosilicone compounds, Quaternary ammonium salts and cationic surfactants having a high adsorption capacity on the surface of the rock.

Table 2 shows the concentrations of the solutions with regard to permeability (pickup) layer.

When the heterogeneity of the reservoir it is recommended that you download a separate rims, since low concentrations, gradually increasing the concentration at the injection subsequent lines.

In field conditions the technological process of the proposed method is as follows.

For injectivity profile alignment layer BV10Tyumen field, with heterogeneity in the permeability of from 50 μm2up to 250 μm2used a solution of aluminium chloride (ll3) and soda ash (Na2CO3).

The work was carried out using standard equipment.

In order to isolate the low part of the reservoir according to table 2 for the permeability of 50 μm2the first slug is pumped by a concentration of 1.5%, the second fringe to the permeability of 50-100 μm2has Konz is the super repellent contains 1.5% of NGL-10. The consumption of reagents take in the ratio of 1: 0.8 to, i.e. 1 t ll3take 0,8 t PA2CO3, it is 0.8 tonnes of sediment in the form of aluminum hydroxide.

Solutions of aluminum chloride with the addition of water-repellent) and soda ash is prepared separately in the two tanks cementing units, which, when injection is used as pumps. Injection solutions are performed simultaneously or sequentially depending on the injectivity of the reservoir. After injection of the required amount of reagents well run under pressure.

The proposed method can improve oil recovery by engaging in the development of previously unreached areas of the reservoir, creating an insulating screen, resistant to erosion and, therefore, provide the duration of the effect.

Sources of information: 1. RF patent 2039224, CL E 21 In 43/24, 1994.

2. RF patent 2108455, CL E 21 In 43/32, 1998 (prototype).

Claims

1. The way of the development of oil deposits at a later stage, including injection into the formation via the injection well an aqueous solution of reagents, forming an insoluble precipitate, as a reagent pump chloride of the metal, forming the most out of the sediment, and oil through the production well, wherein the injection of aqueous solutions of reagents carried out sequentially or simultaneously, as the chloride of the metal used one component from the group of: calcium chloride, magnesium chloride, aluminum chloride, ferric chloride, as another reagent is a salt of polybasic acid or alkali , in addition, a solution of salts of optionally enter a wetting agent, and the concentration of reagents in the solution is selected based on the geological and physical characteristics of the reservoir.

2. The method according to p. 1, characterized in that to obtain a precipitate in the form of a metal hydroxide is used as the other reactant alkali as sodium hydroxide or potassium.

3. The method according to p. 1, characterized in that as the use of water-repellent water-soluble organosilicon compound or anion surface-active substance with a concentration of 0.5-5%.

 

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FIELD: oil and gas production.

SUBSTANCE: invention provides a method of developing oil pool allowing production of oil from water-rich oil reservoir under difficult geological-tectonic conditions in the last development stage. In the method, neutral salt of carbonic acid and acid solution are forced into formation through injecting well with water generated in gas-liquid fringe created in formation. After pumping of neutral salt of carbonic acid, acid solution is pumped by portions alternating with water pumping. Before pumping of acid solution portions beginning by at least second portion, selective insulation of high-permeable formation intervals is performed. Aforesaid neutral salt of carbonic acid utilized is sodium carbonate aqueous solution or aqueous suspension of calcium carbonate and aforesaid acid solution is aqueous hydrochloric acid solution. Selective insulation of high-permeable formation intervals involves use of freshly prepared controllable viscoelastic composition containing water-soluble acrylic polymer, cross-linking agent, thermal stabilizer, surfactant, and water. Summary concentration of acid solution is determined from concentration of neutral salt of carbonic acid on the base of stoichiometric proportions.

EFFECT: increased efficiency of maintaining formation pressure and thereby oil recovery of formation due to leveled displacement front and reduced probability of the rupture of formation rock backbone, and simplified control of phase state of gas-liquid fringe by changing pressure of pumped acid solution portions.

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