RU2065947C1 - Method of developing nonuniform in respect to permeability watered oil strata - Google Patents

Abstract

FIELD: oil and gas production. SUBSTANCE: effective development of permeability-nonuniform watered oil strata includes alternating pumping in of aqueous solution of a partially hydrolyzed polyacrylamide and clay suspension followed by affecting the bed with aqueous solution of a chemical reagent. The latter consists of (in wt %): petroleum or synthetic sulfonates with equivalent weight 330 to 580, 0.25-7; alkylphenols with oxyethylation degree 8-16, 0.25-7; a solvent, 0.25-2.75; water, the balance. EFFECT: increased oil production. 2 tbl

Description

 The invention relates to the oil industry, in particular, to increase oil recovery heterogeneous permeability of water-flooded formations.

 A known method of developing a heterogeneous oil reservoir, including sequentially alternating injection of an aqueous solution of partially hydrolyzed polyacrylamide and clay slurry into the flooded reservoir, followed by water injection (see Instructions for the use of polyacrylamide with clay slurry in flooded wells to increase oil production and limit water inflow. RD 39-5765678-213-87P, 1987).

 The disadvantage of this method is the low efficiency of oil displacement due to the fact that the injection of an aqueous solution of partially hydrolyzed polyacrylamide and clay slurry causes a decrease in the permeability of the washed zones, and subsequent injection of water leads only to partial washing of the oil from the pore channels.

 A known method of oil production, which includes injecting into the formation 0.1-0.3 pore volumes of a solution of a surfactant and carbon dioxide, then a fragmented polymer-gel system and water (see ed. St. N 1809012, MKI E 21 V 43/22, publ. 1993).

This method has the following disadvantages:
low oil recovery efficiency in the late stages of development;
the complexity of oil production technology.

 The closest in technical essence and the achieved effect is the technology of injection into a heterogeneous permeability-flooded oil reservoir of a polymer-dispersed system / PDS /, consisting of an aqueous solution of partially hydrolyzed polyacrylamide and a clay suspension, with a surfactant / surfactant /. (see the Guide to the use of polymeric disperse systems with surfactants to increase oil recovery in Western Siberia. RD 39R-023-90. 1990).

 The disadvantage of this method is its low efficiency due to the use of nonionic surfactants with low oil laundering properties due to insufficiently low interfacial tension and the inability to form a microemulsion phase at the interface with oil.

 The present invention is based on the task of creating an effective method for developing permeable waterlogged oil reservoirs that, due to the integrated effect, increase the filtration resistance of waterlogged zones and, thereby, increase the coverage of the reservoir by water flooding, as well as achieve a more complete washout of oil from the pore space and, in addition to Moreover, to ensure the possibility of its use in formations with different temperatures and waters of various salinity.

 The problem is solved by the fact that in the method of developing permeable heterogeneous waterlogged oil reservoirs, comprising cyclic injection of an aqueous solution of partially hydrolyzed polyacrylamide and clay slurry and subsequent exposure of the reservoir to an aqueous solution of a chemical reagent, oil or synthetic sulfonates with an equivalent mass of 330 are taken as a chemical reagent up to 580, ethoxylated alkyl phenols with a degree of hydroxyethylation from 8 to 16 and a solvent in the following ratio of components in aqueous solution e, wt.

petroleum or synthetic sulfonates with an equivalent weight of 330 to 580 0.25-7.0
hydroxyethylated alkyl phenols with a degree of hydroxyethylation from 8 to 16 0.25-7.0
solvent 0.25-2.75
water rest
As petroleum sulfonates / HC / with an equivalent weight of 400 to 580, for example, sodium, calcium or barium salts of sulfonic acids of oil fractions can be used, namely:
sulfonates, which are the basis of sulfonate additives, for example, S-150, S-300 according to TU 38.101685-84 or emulsifiers, for example, SMDU-2 according to TU 38.101545-75,
petroleum sulfonates according to TU 38.50729-88;
petroleum sulfonate brand "NI" company Vitko Camikl / USA /.

 As synthetic sulfonates / CC /, for example, alkyl sulfonates, mono- and dialkylbenzene sulfonates with an equivalent weight of 330 to 390 can be used according to TU 6-01-1043-86, TU 6-01-18-28-87.

As ethoxylated alkyl phenols can be used, for example:
OP-10 hydroxyethylated alkyl phenol, which is the product of processing a mixture of mono- and dialkylphenols with ethylene oxide, GOST 8433-81;
neonols AF9-10, AF9-12 oxyethylated monoalkylphenols based on propylene trimers, TU 38.507-63-171-91;
Prevocel NG-12 a mixture of ethoxylated isononylphenol based on propylene polymers and the product of the addition of ethylene oxide to propylene glycol, a product of BUNA;
neon α-12, a-14, ethoxylated monoalkylphenols based on a-olefins according to TU 38.507-63-0302-93.

As a solvent can be used, for example:
low molecular weight alcohols isobutyl alcohol (IHD), isopropyl alcohol / IPS /, GOST 9805-76, GOST 6016-77, respectively;
bottoms of butyl alcohol production / KOPVS / according to TU 38.102167-85;
SANAR-101 reagent containing at least 60% low molecular weight alcohol according to TU 2069635-8-92;
mixtures of KOPVS and SANAR or IPS / IHD / with KOPVS or SANAR at a ratio of 8: 1-1: 8.

 A clay suspension is a dispersed system containing particles of clay powder suspended in water used for the preparation of substorm solutions / TU 39-043-74, TU 39-01-08058-81 or OST 39-202-86 /, or technical clay particles / GOST 24902-81 /, or in the absence of the above substances, particles of crude quarry clay, well dissolved in water.

 Injection into the washed zones of a heterogeneous reservoir of a polymer-dispersed system leads to an increase in their filtration resistance. Subsequent injection of a surfactant solution into the reservoir, penetrating into areas not previously covered by the impact, contributes to their involvement in active development, and, ultimately, increased oil recovery.

 A new set of claimed essential features allows to obtain a new technical result, which is expressed in increasing the efficiency of developing heterogeneous permeability of irrigated oil reservoirs, due to the complex effect of increasing the coverage of the reservoir by water flooding and a significant increase in the degree of oil washing.

 An analysis of the known solutions selected in the search process showed that in science and technology there is no object that has the claimed combination of features and the presence of the above properties and advantages, which allows us to conclude that the claimed object meets the criteria of "novelty" and "inventive step".

 To prove the conformity of the claimed method to the criterion of "industrial applicability" we give specific examples of the method.

The development technology in the field is as follows:
A 0.050-0.1% aqueous solution of partially hydrolyzed polyacrylamide and a clay suspension with a density of 1020-1080 kg / m ³ at a volume ratio of 1: / 0.5-5 / are pumped into the formation through injection wells in alternating portions. The indicated cycle is repeated 3-5 times until the working volumes of the polymer dispersed system are pumped. Then the layer is treated with a surfactant solution. The volume ratio of an aqueous solution of partially hydrolyzed polyacrylamide, a clay suspension and an aqueous solution of a surfactant is 1: / 0.5-5.0 /: / 0.25-1.0 /.

 A surfactant solution is prepared by mixing the ACAS, nonionic surfactant, and the solvent in the factory or directly in the field. The resulting solution before use is diluted with water of various salinity at a ratio of 1 / 12-19 /.

 Example 1

 Take 1.76 g of petroleum sulfonate with a molecular weight of 420 / Petronate "HI /, which add 2.06 g of neonol AF9-12, 2.06 g of solvent / KOPVS-SANAR at a ratio of 1: 1 /. The resulting mixture is stirred until a homogeneous mass and add water with a salinity of up to 300 g / l to 100 g of the total mass.

 Similarly, by varying the ratio of components, other formulations are also prepared.

 The prepared compositions are tested for stability in water with different salinity and at different temperatures, as well as the ability to form a microemulsion phase. To determine the viscosity and pour point, compositions containing no water are used. The obtained data on the determination of the physicochemical properties of anhydrous compositions and their solutions are given in table. 1.

 As can be seen from the data, water-free formulations have a low pour point, low dynamic viscosity, which gives them stability during storage and transportation, in addition, their solutions are stable under water conditions of different salinity and at different temperatures.

 Evaluation of the effectiveness of the claimed invention and the prototype method is carried out in laboratory conditions by the following indicators: a change in the permeability of high and low permeability layers of the reservoir model and the increase in oil displacement coefficient.

 The tests are carried out on models of a heterogeneous permeability formation with two hydrodynamic unbound layers. The latter are tubes with a length of 0.4 m and a diameter of 0.018 m, fixed with ground quartz sand and attached to the same pressure container. Initially, water is pumped through the model in an amount of 3.0 pore volumes / bp /, then a rim of reagents is introduced, after which, again, water is pumped in an amount of 3.0 bp. The research results are given in table. 2.

 Example 2

 An aqueous solution of partially hydrolyzed polyacrylamide of 0.05% concentration and a clay suspension of 3% concentration in the form of three identical cycles of 0.1 PO each are pumped into the waterflood model. The total volume of an aqueous solution of partially hydrolyzed polyacrylamide and clay suspension is 0.3 PO. The increase in oil displacement ratio amounted to 10.5% / cm. tab. 2, experience 1 /.

 In the remaining examples / experiments 3, 5, 6, 7 / the injection of an aqueous solution of partially hydrolyzed polyacrylamide and clay suspension is carried out analogously to example 2.

 Example 3

 A nonionic surfactant, neonol AF9-12, 4.0% concentration is pumped into the reservoir model. The growth rate of oil displacement is only 3.0% / cm. tab. 2, experience 2 /.

 Example 4 / prototype /.

 A 0.05% aqueous solution of partially hydrolyzed polyacrylamide and a clay suspension of 3.0% concentration are pumped into the reservoir model, then a nonionic surfactant neonol AF9-12, 4.0% concentration is pumped.

The growth rate of oil displacement is 14.5% / cm. tab. 2, experience 3 //
Example 5 / the claimed method /.

 At first, an aqueous solution of partially hydrolyzed polyacrylamide of 0.05% concentration and a clay suspension of 3.0% concentration are pumped into the reservoir model, then a surfactant solution / cm. tab. 1, composition 1 / with a volume ratio of injected components of 1: 1: 0.25. The increase in oil displacement coefficient is 20.2% / cm. tab. 2, experience 5 /.

 The table below contains data on determining the effectiveness at different volume ratios of an aqueous solution of partially hydrolyzed polyacrylamide, a clay suspension and a surfactant solution.

 As can be seen from the above data, the injection of PDS significantly changes the ratio of permeability between high and low permeability layers / runway: NFP /. Injection of a neonol AF9-12 solution and the inventive surfactant solution / cm. tab. 1, composition 1 /, practically without changing the ratio of permeability between the runway and the NPP contributes to oil washing, and, when using the claimed surfactant solution, the increase in oil displacement coefficient is significantly higher than when using the solution of only one surfactant AF9-12.

 Thus, a comparison of the results obtained from the use of PDS, AF9-12 solution, the inventive surfactant solution, AF9-12 PDS and the inventive method shows that the combined use of PDS with surfactant solution leads to the achievement of a technical result significantly exceeding the total result from their separate use .

Using the proposed method for the development of heterogeneous permeability of waterlogged oil reservoirs allows to achieve the following technical and economic advantages:
increase the growth rate of oil displacement;
to develop formations with different temperatures and water contents of different salinity;
dispose of industrial waste;
in addition, the method uses reagents available from the domestic industry.

 Pilot tests conducted at the Tatneft Production Association at the Romashkinskoye field made it possible to obtain 51.6 thousand tons of additional oil through the implementation of the method as of 1.06.93. TTT1 TTT2 TTT3

Claims (1)

 A method of developing a water-filled oil reservoirs of heterogeneous permeability, comprising the cylindrical injection of an aqueous solution of partially hydrolyzed polyacrylamide and a clay suspension and subsequent exposure of the formation to an aqueous solution of a chemical reagent, characterized in that a solution containing oil or synthetic sulfonates with an equivalent weight of 330 is used as a chemical reagent up to 580, ethoxylated alkyl phenols with a degree of hydroxyethylation from 8 to 16 and a solvent in the following ratio of components per Ore wt. Petroleum or synthetic sulfonates with an equivalent weight of 330 to 580 0.25 7.0
Oxyethylated alkyl phenols with a degree of hydroxyethylation from 8 to 16 0.25 7.0
Alcohol solvent 0.25 2.75
Water Else

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