RU2247224C2 - Method for isolation of bed waters influx into oil and gas wells - Google Patents

Abstract

FIELD: mining industry.

SUBSTANCE: method includes feeding of compound for selective water isolation, after its pumping hydrophobic liquid or gas are additionally pumped for pressing said compound from face into bed for distance, equal to radius of formed screen, while said compound will take on a form of cover, lower portion of which during contact with water become impenetrable for liquid or gas coming after compound, and upper portion is carried into well during its launch.

EFFECT: higher efficiency.

1 ex, 1 dwg

Description

The invention relates to the oil and gas industry, in particular to the field of development of oil and gas fields with bottom water, and can be used to isolate waterlogged formations in production wells.

A known method of isolating the influx of formation water, which consists in injecting calcareous mixtures for mining and drilling operations (SIGB) into the borehole zone of the reservoir as a composition for selective waterproofing, while in contact with the reservoir water, SIGB hardens to form a dense stone [RF Patent No. 2158356, class E 21 B 33/138, 1999].

The disadvantage of this method is that to create a screen requires a large amount of waterproofing composition. To create a screen with a radius of 5 m and a thickness of 2 m, about 30 m ^{3 of} composition is required. In addition, the disadvantages of the method include the difficulty in developing the well as a result of penetration of killing fluid into the bottomhole zone during the injection of the waterproofing composition, as well as a decrease in the oil-saturated (gas-saturated) thickness of the formation.

The closest technical solution selected for the prototype is a method of limiting the flow of water into the well, comprising sequentially injecting into the formation an insulating solution based on an aqueous solution of polyacrylamide and a crosslinking agent based on an aqueous solution of a salt of a polyvalent metal with preliminary introduction of a magnetic substance into the insulating material by lowering it into the magnet well, by putting the well into operation until the insulating solution which has penetrated into it is completely removed from the oil-saturated interval of the formation and stop oh well before the introduction of a crosslinking agent [RF Patent No. 2079645, cl. E 21 B 43/32, 1994].

The disadvantage of this method is the difficulty of implementation, as well as the fact that the insulating solution can be removed from the formation into the well not only from the oil-saturated, but also from the water-saturated zone.

The objective of the invention is to increase the efficiency of isolation of formation water, reduce the cost of the work process, minimize contamination of the bottomhole zone of the well and reduce the time for its subsequent development.

The technical result when creating the invention is to develop an effective method of isolating formation water while reducing the volume of the composition necessary to create a water barrier screen with minimal contamination of the bottomhole zone of the well.

The solution of the problem and the technical result are achieved by the fact that in the method of isolating the influx of formation water into oil and gas wells, including injecting a composition for selective water isolation, after it is injected, a hydrophobizing liquid or gas is additionally pumped to push the specified composition from the bottom of the well deeper into the formation, equal to the radius of the created screen, while this composition will take the form of a shell, the lower part of which upon contact with water becomes impermeable to those injected after These hydrophobizing liquid or gas and the upper part is carried into the well when it is starting to work.

Unlike the prototype, the calculated volume of the composition for selective isolation (1, drawing) is pumped into the well, then a hydrophobizing liquid (2, drawing) or gas is pumped in order to push the selective composition away from the bottom by a distance equal to the radius of the created screen, and at the same time clean bottom hole zone of the well. In this case, the selective composition will take the form of a shell, the lower part of which (3, drawing) will become impermeable upon contact with water and cannot be broken by the hydrophobizing liquid or gas injected after the selective composition, and the upper part will be carried out into the well when it is put into operation.

The stability of the movement in the reservoir of liquids will be ensured by the selection of properties [Barenblatt GI, Entov VM, Ryzhik VM The theory of non-stationary filtration of liquid and gas. M .: Nedra, 1972, 287 pp.] As a selective composition and hydrophobizing fluid. If the reservoir isotropic and selective composition takes the form of a hemisphere, then the required volume of the composition is equal to:

where V _SK - the volume of the selective waterproofing composition, m ³ ;

m - formation porosity, fractions of a unit;

r ₁ is the radius of the outer surface of the hemisphere, m;

r ₂ is the radius of the inner surface of the hemisphere, m;

V ₁ is the volume of a sphere of radius r ₁ , m ³ ;

V ₂ is the volume of a sphere of radius r ₂ , m ³ .

In the case of an anisotropic reservoir and with a difference in permeability vertically and horizontally, the screen will take the form of an ellipsoidal shell. Its lower part will be impervious to water, since the composition for waterproofing forms a strong connection in contact with water.

Comparison with the prototype allows us to conclude that the claimed method of isolating the influx of formation water differs from the known one in that the working volume of the selective composition is first pumped into the well, and then the necessary volume of hydrophobizing liquid or gas is necessary to push the selective composition from the bottom by a distance equal to the radius of the created screen .

This allows us to conclude about the inventive step of the proposed method.

Example

An oil well reveals an isotropic formation with a thickness of 5 m and a porosity of 0.2. The perforation interval is 4 m. As a result of pulling the formation water cone (4, drawing), the lower two meters of the perforation interval are flooded. It is necessary to create a water insulating screen with a radius of 5 m and a thickness of 0.2 m. For this, V _ck = 2 / 3πm (r $\genfrac{}{}{0ex}{}{\text{3}}{\text{one}}$ -r $\genfrac{}{}{0ex}{}{\text{3}}{\text{2}}$ ) = 2 / 3π0,2 (5 ³ -4,8 ³ ) = 6.03 m ^{3 of} composition for selective waterproofing (1, drawing), for example, heavy pyrolysis resin mixed with hydrochloric acid or calcareous mixture for mining drilling operations ( SIGB).

Then pump hydrophobizing fluid (2, drawing), for example, oil in volume:

where V _gc is the volume of the hydrophobizing composition, m ³ .

V _gc = 2 / 3π · 0.2 · 4.8 ³ = 46.3 m ³ .

The well is left for the time necessary for setting the selective composition in the zone of contact with water. As a result, a water insulating screen in the form of a half-shell is formed in the bottom-hole zone (3, drawing).

Using the proposed method in comparison with existing gives the following advantages:

1. significantly reduces the amount of composition for selective waterproofing;

2. bottomhole zone is cleaned up and well development conditions are improved;

3. the oil-saturated (gas-saturated) formation thickness in the bottomhole zone of the well does not decrease;

4. The method can be applied in horizontal wells.

Sources of information

1. RF patent No. 2158351, cl. E 21 B 33/138, 1999.

2. RF patent No. 2079645, class. E 21 In 43/32, 1994 (prototype).

3. Barenblatt G.I., Entov V.M., Ryzhik V.M. The theory of non-stationary filtration of liquid and gas. M., Nedra, 1972, 287 pp.

Claims (1)

A method of isolating the influx of formation water into oil and gas wells, including injecting a composition for selective waterproofing, characterized in that after it is injected, a hydrophobizing liquid or gas is additionally pumped to push said composition from the bottom of the well into the formation at a distance equal to the radius of the created screen, while the specified composition will take the form of a shell, the lower part of which upon contact with water becomes impermeable to water-repellent liquid or gas injected after it, and the upper part It is carried into the well when it is starting to work.