RU2273663C2 - Method for petroleum displacement from oil pool - Google Patents

Abstract

FIELD: biotechnology, petroleum-extracting industry.

SUBSTANCE: invention relates to microbiological methods for extraction of residual oil from flooded pools at the late stage of the deposit exploitation. Method involves the successive pumping in an aqueous solution of mixture of active silt with a stabilizing agent into forcing stratum wherein starch and hydrolysis sugar are used in the following ratio of components, wt.-%: active silt, 0.1-5.0; starch, 0.1-1.0; hydrolysis sugar, 0.5-3.5, and water, the balance. Using the method in petroleum-extracting industry allows stabilization active silt particles in volume of the pumped solution and more penetration into stratum, to enhance effectiveness of petroleum extraction from heterogeneous collectors by 12.8%, to diminish flooding degree of extracted production and nonproductive water pumping in.

EFFECT: improved method for displacement.

2 tbl, 3 ex

Description

The invention relates to biotechnology used in the oil industry, in particular to microbiological methods for extracting residual oil from watered formations at a late stage of field operation.

A known method of waterflooding an oil reservoir, including the injection into the reservoir of a hydrogel with immobilized cells of marine aerobic microflora and polycyclic quinones (Pat. RF No. 2023872, MKI E 21 V 43/22). The disadvantage of this method is the use of only aerobic hydrocarbon-oxidizing bacteria and an expensive hydrogel.

The achieved result closest in technical essence is the method of developing an oil reservoir (Pat. RF No. 2158360 dated 10.27.2000, Bull. No. 30), in which activated sludge from industrial enterprises and biostimulants are used as a source of microorganisms. The disadvantage of this method is the low efficiency of oil displacement from the reservoir, and the rapid sedimentation of dispersed particles of sludge, which are agglomerates of microbial cells, when dissolved in the injected water.

The technical result of the invention is to increase the stability of microorganisms of activated sludge in the volume of solvent (water) during the injection process, to improve the filterability in a porous medium and, as a result, increase oil recovery.

The problem is solved in that in the method of displacing oil from the formation, which consists in sequentially injecting into the formation an aqueous solution of activated sludge, a biostimulant, hydrolysis sugar, according to the invention, first an aqueous solution of activated sludge mixed with starch is pumped at a ratio of 5: 1, then hydrolysis is pumped sugar in the following ratio, wt.%:

Active sludge 0.1-5.0 Starch 0.1-1.0 Hydrolysis sugar 0.5-3.5 Water Rest

Activated sludge is a concentrate of bacteria and other microorganisms together with organic and mineral residues of their decomposition in the form of a powder with a characteristic odor. Obtained by thickening liquid activated sludge from treatment facilities of industrial plants and drying on spray dryers according to TU 2458-001-33782561-2000. Sludge contains spore-forming forms of bacteria, 80-90% of organic substances and 7-12% of mineral elements. Organic matter includes protein, nucleic acids, lipids, vitamins, macro and micronutrients.

As a stabilizer of activated sludge particles in a solution, a polymer of plant origin is used, a representative of the polysaccharide class — starch, the composition of which is expressed by the general formula (C ₆ H ₁₀ O ₅ ) _n . In addition, an aqueous solution of starch in the composition with AI is used: to increase the filterability of the composition in a porous medium, which allows the reagent to penetrate deeper into the formation, increasing the coverage of the formation by water flooding, and as an additional power source for bacteria of activated sludge and formation microflora. A particularly valuable advantage of the use of starch is its ability to determine the dispersion of phases in an aqueous medium containing microorganisms, since activated sludge is a multicomponent system of organic and inorganic components.

Hydrolysis sugar (HS) is recommended to be added to activate microflora of activated sludge and formation microflora. HS is formed during the production of cellulose from wood, the main component is monosaccharides (28-32%), organic acids, macro- and microelements (TU 2458-001-33782561-2001). GS has a specific gravity of 1.25 g / cm ³ , pH 5.0, a viscosity of 70-100 MPa · s.

The specified ratio of the components injected into the reservoir composition provides the greatest degree of oil recovery from the reservoir.

The method is carried out using commercially available units and tankers and does not require special arrangement of wells.

The effectiveness of the invention was tested in laboratory and field conditions.

Example 1. The stabilization efficiency of activated sludge particles in the injected water was determined experimentally by the time of sedimentation of particles in a solvent.

Solutions of activated sludge and starch in certain proportions are added to graduated cylinders per 100 ml (see Table 1). Then, at certain intervals, the volume occupied by the settled composition is noted. As a control, a solution of activated sludge without a stabilizer (starch) is added to the same cylinders.

The data in table 1 show that the starch, which is proposed as a stabilizer of dispersed particles of activated sludge in solution, is starch is an effective reagent (experiment 1-6) compared with the control (experiment 7-9).

Example 2. The effectiveness of the method was determined simultaneously on reservoir models of a porous medium by filtering a solution of this composition and a displacing agent - water. As reservoir models of the porous medium, disintegrated core material was used. Filtration experiments were carried out according to the well-known OST method (39-195-86). The data of the filtration results are given in table.2.

The results of filtration experiments on reservoir models showed the following: in experiments 1-4, the permeability reduction was in the range of 48.7-83.7%, the oil recovery increased from 7.5-12.8%, and when filtering the composition according to the prototype, the permeability reduction was 27, 8% (experiment No. 5) and oil recovery growth amounted to 5.1%.

The experience data indicate the effectiveness of the composition used in the method of oil displacement from the reservoir.

Example 3. The implementation of the method in the field. A method of developing an oil reservoir and regulating the permeability of a water-saturated reservoir is based on pumping the rims of the bioreagent composition into injection wells. The volume of bioreagents injected into one treated injection well depends on the specific geological and physical properties of the formation, the physicochemical fluids saturating the formation, the stage of development of the oil field, the degree of water cut of the produced products, and may be 20-100 m ³ .

Field tests of the technology of areal microbiological exposure were carried out on the Volkovskaya area of the Volkovskoye field of Bashkortostan. The production well stock was 47, incl. 37 producing and 10 injection wells. The main industrial oil-bearing object in the field is the Tournaisian limestones. The reservoir layers are composed of both highly permeable pore-cavernous and low porous and poorly permeable limestones. The porosity is 0.12 units, the permeability is 0.020 μm ² . The viscosity of the oil in reservoir conditions of 7.03 MPa · s, a density of 843 kg / m ³ , reservoir temperature of 26 ° C. The water cut of the produced products is 86.2%, the average injection rate of injection wells is 76 m ³ / day.

The injection of bioreagent solutions was carried out with a CA-320 aggregate of 60 m ^{3 of an} aqueous solution of a mixture of activated sludge (3.0 t), starch (1.0 t) and then hydrolysis sugar (2.5 t) and by forcing in a quantity of buffer liquid (fresh water) 10-15 m ³ . Then they switched to normal operation. The selection of fluid is carried out through production wells.

2 months after the injection of bioreagent solutions into injection wells, a decrease in the water cut of production wells from 86 to 80% or more was observed, the specific technological efficiency per treatment was 1.5-2.0 thousand tons, per 1 ton of bioreagents injected up to 600 tons additional oil.

As shown by field trials, the application of this method is most effective on oil reservoirs that are in a late stage of development, where alignment of injection well profiles, isolation of water-washed zones, and limitation of water inflow are necessary.

The technology for applying the method is simple and consists in pumping into an injection well and forcing the composition from the wellbore into the formation with water.

Thus, the obtained data show that the inventive method for developing an oil reservoir is highly effective. The application of the method in the oil industry allows you to:

- stabilize activated sludge particles in the volume of injected solution and deeper penetration into the reservoir;

- increases the efficiency of oil extraction from heterogeneous reservoirs up to 12.8%;

- reduces water cut of extracted products and unproductive water injection.

The method is technologically simple and does not require expensive equipment.

Table 1
The effect of starch on the dynamics of sedimentation of activated sludge Experience number The content of components, wt.% The volume of the settled composition, depending on the settling time, ml activated sludge starch water 0 min 30 minutes 60 min 120 min 240 min one 0.005 0.1 99.89 one hundred 98.0 97.0 92.0 89.0 2 0.1 0.1 99.80 one hundred 98.7 96.8 91.8 87.5 3 0.5 0.5 99.00 one hundred 98.8 96.8 90.7 87.0 four 1,0 1,0 98.00 one hundred 98.3 96.1 89.5 86.7 5 3.0 1,0 96.00 one hundred 98.1 96.3 89.0 84.8 6 5,0 1,0 94.00 one hundred 97.5 96.0 89.0 80.1 7 0.1 - 99.90 one hundred 70 20,0 0.5 0.5 8 1,0 - 99.00 one hundred 63 13.0 0.7 0.7 9 5,0 - 95.00 one hundred fifty 9.3 1,0 1,0

table 2
Filter Results Experience number The order of injection of reagent solutions The concentration of reagents,% Volumes
injected solutions of p..o composition Permeability reduction,% Oil recovery growth,% activated sludge starch hydrolysis sugar one 2 3 four 5 6 7 8 one Injected water (mineralized r-1,1
g / cm ³ ) Fresh water 0.01 The composition of aqueous solutions of activated sludge with starch 0.1 0.1 0.2 Hydrolysis sugar solution 0.5 0.1 Fresh water 0.01 Pumped water 3,5 48.7 7.5 2 Pumped water Fresh water 0.01 The composition of aqueous solutions of activated sludge with starch 1.0 0.5 0.2 Hydrolysis sugar solution 1,5 0.1 Fresh water 0.01 Pumped water 3,7 59.3 8.1 3 Pumped water Fresh water 0.01 The composition of aqueous solutions of activated sludge with starch 3.0 1,0 0.2 Hydrolysis sugar solution 2,5 0.1 Fresh water 0.01 Pumped water 72.1 9.7 four Pumped water Fresh water 0.01 The composition of aqueous solutions of activated sludge with starch 5,0 1,0 0.2 Hydrolysis sugar solution 3,5 Fresh water 0.01 Pumped water 83.7 12.8 5 Injected water (prototype) Fresh water horn (prototype) 0.01 Active sludge solution (prototype) 5,0 - 0.2 Hydrolytic sugar solution (prototype) 3,5 0.1 Fresh water horn (prototype) 0.01 Injected water (prototype) 27.8 5.1

Claims (1)

A method of displacing oil from a formation, which consists in sequentially injecting an aqueous solution of activated sludge, a biostimulant into the formation, characterized in that the aqueous solution of activated sludge is pumped in a mixture with starch before injecting a biostimulator - hydrolysis sugar, in the following ratio, wt.%: Active sludge 0.1-5.0 Starch 0.1-1.0 Hydrolysis sugar 0.5-3.5 Water Rest