RU2304706C2 - Method of controlling development of nonuniform oil formation - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: invention relates to methods for developing permeability-nonuniform formations. In a method of controlling development of nonuniform oil formation comprising consecutively alternating injection of insulating composition, working substance, and water into formation, consecutively alternating injection is effected through injecting and producing wells supplemented by 24-h ageing performed after injection of insulating composition, said working substance and water utilized being a system formed by adding 0.5 to 99% of all-purpose reagent used in oil production (RDN-U) to fresh, waste, or formation water, and said insulating composition being a grouting composition based on cement materials or organosilicon compounds, or aqueous solution of polyacrylamide and chromium-containing crosslinking agent, or solution of alkali metal silicate and activator, or oil-in-water emulsion.

EFFECT: increased development efficiency due to increased coverage of formation by isolating high-permeability portions of formation both from withdrawal side and from injection side and due to more complete displacement of oil from low-permeability formations.

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Description

The invention relates to the oil industry, in particular to methods for developing reservoirs that are not uniform in permeability.

A known method of regulating the development of a heterogeneous formation (RU 2191894 C1, E2B 43/22, 2002.10.27), carried out by sequentially alternating injection into the formation of a water-soluble polymer, an aqueous solution of alkali and an aqueous solution of aluminum salt, as an alkali use an aqueous solution of sodium silicate or alkaline the caprolactam production effluent is 8.0-15.0% concentration, and the aluminum salt is the aluminum-containing waste product of the production of benzene alkylation with olefin 5.0-25.0% concentration, and an additional buffer fluid is injected between the injections of a water-soluble polymer, an aqueous alkali solution and an aqueous solution of aluminum salt. In the last cycle, the injection of a water-soluble polymer is carried out by adding chromium acetate to it.

The disadvantage of this method is the low efficiency in low permeability reservoirs due to the fact that the components of the alkali - aqueous solution of aluminum salt are not mixed well enough and the gel formed is unstable and is quickly washed out by formation waters.

A known method of developing a heterogeneous formation, including the injection of rims of solutions of partially hydrolyzed polyacrylamide (PAA) and surfactants in the form of rims through an injection well (Surguchev M.L. Secondary and tertiary methods of increasing oil recovery. - M .: Nedra, 1985, p. 169).

The disadvantage is the short-term effect associated with the fact that the PAA in the form of a viscous solution moves quickly enough from the injection line to the production well.

The closest in technical essence, taken as a prototype, is a method of flooding an oil reservoir (RU 2079641 C1, cl 6 E21 43/22, bull.14, 1997), including the injection of a working agent and water into the reservoir through the injection well, and through the producing a well of a rim of a 0.05-2.0% solution of powdered cross-linked polyacrylamide, where a solution of a nonionic surfactant, for example, a 0.05% aqueous solution of neonol, is used as a working agent.

The disadvantages of this method are: the creation of a blocking screen only from the side of the fluid withdrawal, which practically does not affect the increase in the coverage coefficient of the formation by the impact and does not exclude an increase in water cut in the well’s production due to the bending of the low-volume blocking screen with water, and low oil washing ability of the composition due to the high adsorption of the neonol solution on the surface of the rock.

The technical result of the invention is to increase the development efficiency by increasing the coverage of the formation by exposure by isolating highly permeable sections of the reservoir both from the selection side, and from the side of injection and more complete displacement of oil from low permeability layers.

The technical result is achieved by the fact that in the method for regulating the development of a heterogeneous oil reservoir, which includes sequentially alternating injection into the reservoir through wells of an insulating composition, a working agent and water, sequentially alternating injection is carried out through injection and production wells, after injection of the insulating composition they are held for 24 hours, as a working agent and water use the system formed by adding 0.5-99 wt.% universal reagent for oil extraction RDN-U in fresh sludge and wastewater-produced or produced water, as an insulating composition, use a grouting composition based on cement materials or organosilicon compounds or an aqueous solution of polyacrylamide and a chromium-containing crosslinking agent, or a solution of alkali metal silicate and activator, or direct emulsion.

The used reagent RDN-U is produced according to TU 2458-001-33539748-2004, is a composition for oil production, containing wt.%:

Nonionic surfactants 18-30 Paraffin solvent 20-70

As an insulating composition, grouting compositions based on cement materials or organosilicon compounds are used, for example, a composition based on Portland cement grouting with a water-cement ratio of 0.5 and with a content of hydroxyethyl cellulose of 0-0.5 wt.% By weight of water, product 119-204 according to TU- 6-02-1294-84 - an organosilicon oligomeric compound, or aqueous solutions of PAA polyacrylamide and a chromium-containing crosslinking agent (crosslinked polymer systems, viscoelastic compounds), or solutions of alkali metal silicates and activators, for example, thick glass with an activator up to 1.5 wt.%, citric, boric or hydrochloric acid, or direct emulsions, for example, a wide fraction of heavy hydrocarbons SHFTU or diesel fuel, or crude oil 30-90 wt.% and other water can be used as an activator .

The present invention solves the technical problem of ensuring uniform advancement of the displacement front and improving the washing properties of the solution.

The proposed method for regulating the development of a heterogeneous oil reservoir was modeled in laboratory conditions. For this, a reservoir model was assembled, which was two metal tubes with a diameter of 30 mm and a length of 450 mm, filled with quartz sand. One current tube (with a permeability of 1.1 μm ² ) imitated a low-permeability section of the reservoir, the other (with a permeability of 5 μm ² ) - a highly permeable section. The studies were carried out in accordance with OST 39-195-86 “Oil. A method for determining the coefficient of oil displacement by water under laboratory conditions. "

First, oil was displaced by water from both current tubes until 100% water cut of one of them was reached. Then, a rim of an aqueous solution of polyacrylamide with a concentration of 0.3 wt.% And chromium acetate 0.03 wt.% - a crosslinked polymer system (ATP) was pumped through the injection well model in an amount of 0.1 of the pore volume. To carry out the gelation process, the reservoir model was left to gel for 24 hours - exposure is carried out. Then 0.1 pore volume of the solution rim of 5 wt.% RDN-U was pumped into the model. At the same time, injection was carried out through the model of the producing well according to the method described above, the difference from it was that instead of the ATP, a rim of an aqueous solution of polyacrylamide with a concentration of 1 wt.% With chromium acetate 0.1 wt.% - viscoelastic composition (HCL) was pumped in the amount of 0.1 of the pore volume. After that, fresh water was introduced into the model until 100% water cut was again obtained from the highly permeable section of the reservoir model. Based on the data obtained, the final oil recovery coefficient was calculated.

Experiments were conducted on the displacement of oil from the specified reservoir model by a known method taken in the form of a prototype (RU 2079641 C1, E21B 43/22, bull.14, 1997), which consists in pumping an aqueous solution of powdered cross-linked polyacrylamide into the reservoir from the side from the injection side - an aqueous solution of nonionic surfactants. The experimental results are shown in the table.

As can be seen from the above data, the proposed method, which includes sequentially alternating injection of an insulating composition and an aqueous solution of the RDN-U reagent into the producing and injection wells, is operable with the claimed parameters and it achieves an oil displacement coefficient higher than by the method adopted for the prototype.

Table No. p.p. Defined Parameters 1.2% PAA + 5% nonionic surfactants (prototype) The inventive method one Oil displacement coefficient 0.57 0.67 2 Water repellent effect * 1.3 2.2 * The hydrophobic effect is evaluated by the change in the volumetric rate of water filtration before and after treatment of the formation with the analyzed system.

Claims (1)

A method of regulating the development of a heterogeneous oil reservoir, including sequentially alternating injection into the reservoir through wells of an insulating composition, a working agent and water, characterized in that the sequentially alternating injection is carried out through injection and production wells, after the injection of the insulating composition they are held for 24 hours as a working agent and water use the system formed by adding 0.5-99 wt.% universal reagent for the extraction of oil RDN-U in fresh or waste - commercial, or formation water, as an insulating composition use a cement slurry based on cement materials or organosilicon compounds, or an aqueous solution of polyacrylamide and a chromium-containing crosslinking agent, or a solution of alkali metal silicate and activator, or direct emulsion.