RU2196883C2 - Composition for increasing oil recovery - Google Patents

Abstract

FIELD: oil producing industry; applicable for increasing oil recovery from formations by their waterflooding in primary and secondary stimulations of formations and in shutoff of water inflows to oil wells, and for regulation of filtration flows in oil formations. SUBSTANCE: composition for increasing oil recovery containing aluminum chloride, carbamide, phosphoric acid and water, additionally has zinc chloride with the following ratio of components, mas. %: aluminum chloride, 10-15; zinc chloride, 10-15; carbamide, 35-55; phosphoric acid. 1.0-8.0; water, the balance. EFFECT: formation of strong gels, extended temperature range of application, reduced corrosion attack on oil field equipment. 2 tbl

Description

 The invention relates to the oil industry and can be used to increase oil recovery by flooding during primary and secondary impact on the reservoir, as well as to isolate water inflows to oil wells, to regulate the filtration flows of oil reservoirs.

 Known gel-forming compounds based on polyacrylamide (Yumarilov A.Yu. Isolation of formation water. M: Nedra, 1976), structured water-soluble polyelectrolytes (Kalashnikov B.M., Yusupov I.G., Sivukhin A.A. isolation of water inflows. Oilfield business. RNTS VNIIOENG, 1981. - 4). Also known are gel-forming compositions based on zeolites (US Pat. US 4257813, class 106-74, 4640361 class 116-258). A disadvantage of the known compositions is the high gelation rate, low structural stability, which limits the scope of the compositions.

The closest technical solution is a composition for increasing oil recovery, containing the following components in their ratio, wt.%:
Aluminum Chloride - 20-30
Urea - 30-55
Sulfuric acid or waste of its production - 10-15
Nitrogen-containing aromatic inhibitor or phosphoric acid - 0.1-0.5
Water - Else
(RF patent 2143550, E 21 B 43/22, 12/27/1999).

 This composition does not form sufficiently strong gels, which is technologically disadvantageous when processing wells.

 The objective of the present invention is to provide a composition for increasing oil recovery, forming strong gels in the formation with an extended temperature range for its use, as well as reducing the corrosive effects on field equipment.

The problem is solved in that the composition for increasing oil recovery, containing aluminum chloride, urea, phosphoric acid and water, additionally contains zinc chloride, in the following ratio, wt.%:
Aluminum Chloride - 10-15
Zinc Chloride - 10-15
Urea - 35-55
Phosphoric acid - 1.0-8.0
Water - Else
The composition may contain aluminum chloride production waste as aluminum chloride, and urea production waste as urea.

 Aluminum chloride production waste is produced according to TU-38.102163-84.

 Urea waste is produced according to TU-38.30236-88.

The composition is prepared as follows:
The calculated amount of zinc chloride and aluminum chloride (or waste from its production) is loaded into the reactor, then urea (or waste from its production) is added with constant stirring. The temperature in the reactor is maintained at 25-30 ^{° C.} by supplying steam to the cooling jacket. The reaction mixture is kept for 2-3 hours until a uniform transparent solution is formed, then phosphoric acid is added, the solution is kept for another 1 hour, after which it is poured into a railway tank for delivery to the injection site.

 Thus prepared composition in the reservoir forms a gel, which leads to selective blocking of highly permeable areas.

 The resulting composition is a commodity form and can be used without additional operations for injection directly at the well.

 In laboratory conditions, studies were conducted of the dependence of the gelation time on the concentration of phosphoric acid, on temperature.

 The viscosity and density of the composition were measured during gelation. The effect of gelation on the permeability of a porous medium in water is studied.

 The research results are shown in table 1.

As can be seen from the table, the gelation time decreases significantly with increasing temperature to 95 ^o C.

Examples of the preparation of the composition
Example 1 (for a known composition).

30.0 g of aluminum chloride, 30.0 urea was dissolved in 40.0 ml of water. The gelation time at 65 ^o C is 312 hours, at 60 ^o C - 720 hours, at a lower temperature the gel does not form.

 Example 2

In a flask containing 300 ml of aluminum chloride (according to TU-38.102163- / 84), 300 ml of ZnCl ₂ , add 400 g of urea (TU-38.30236-88) and stirred for 2 hours. Then add 8% phosphoric acid and stirred for 1 hour. The resulting solution was placed in an oven and kept at a given temperature. The gel time of the proposed composition at 75 ^o C was 24 hours, at 50 ^o C - 195 hours (experiment 7, table 1).

 Example 3

In a flask containing 300 ml of AlCl ₃ (TU-38.102163-84), 300 ml of ZnCl ₂ , add 400 g of carbamyl (TU-38. 30236-88), stirred for 2 hours. Then 5% phosphoric acid is added and stirred for 1 hour. The resulting solution has an initial viscosity of 1.94 mm g / s (at T = 20 ^o C), within 10 hours the viscosity increases only to 2.25 mm g / s. After 24 hours, a gel with a kinetic viscosity of 29.62 mm g / s is formed (experiment 4, table 1).

 Example 4

 The preparation of the composition is carried out analogously to example 2.

The water-insulating ability of the gel was determined in laboratory conditions by the following method: first, water and then the gel-forming composition were sequentially filtered through core samples with known filtration-capacity properties. The temperature of the experiments is 75 ^o C (experiment 7, table 1), gelation time 24 hours. After gel forming, the water was again filtered and the decrease in permeability was evaluated before and after gel injection. The permeability of model 1 decreased by 9.6 times and reached 4.7 μm ² , the permeability of model 2 decreased by 9.8 times and amounted to 4.2 μm ² .

 Thus, according to the results of filtration experiments, it can be stated that the proposed composition showed good waterproofing properties.

In general, based on studies of the properties of the composition to enhance oil recovery, it follows that:
1. The use of the inventive composition in oil products and increase the efficiency of oil recovery from heterogeneous formations. The addition of zinc and phosphoric acid to the known composition can significantly improve the gelation time and reduce the temperature range of gel formation, and has anti-corrosion properties.

 3. The constituent components are not scarce, have a low cost, since they are large-tonnage waste from petrochemical industries.

 4. The proposed structure is the finished product form, which is an important fact when transporting to the place of injection.

 5. The developed composition is a transparent, finely dispersed solution with an initial kinematic viscosity of 1.5 to 2.2 mm g / s and an adjustable gelation time. The viscosity of the solution increases depending on the concentration of the constituent components and temperature for 1-3 days.

 6. The waterproofing composition is not aggressive, because phosphoric acid is a corrosion inhibitor.

 7. The result of the treatment is a selective decrease in the permeability of only aquifers.

Claims (1)

Composition to enhance oil recovery, containing aluminum chloride, urea, phosphoric acid and water, characterized in that it additionally contains zinc chloride in the following ratio, wt. %:
Aluminum Chloride - 10-15
Zinc Chloride - 10-15
Urea - 35-55
Phosphoric acid - 1.0-8.0
Water - Else

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