SU1677274A1 - Method of developing multi-layer oil deposits - Google Patents

Abstract

The invention relates to an oil producing industry. The goal is to increase oil recovery due to an increase in reservoir coverage by flooding. To do this, simultaneously with the injection of water into the injection wells, the water-repellent fluid is pumped into the high-watered production wells located in the zone of influence of the injection wells. The injection of a hydrophobic fluid is carried out at a pressure that opens the cracks and until the pressure in the treated area reaches the initial pressure. The injection of a hydrophobic fluid during the development process is periodically repeated after a sharp increase in the water-cut of production wells. Using this method allows to reduce the phase permeability of kefte-saturated formations for water and to increase it for oil and to reduce the water-cut of production wells. 4 tab. w Ё

Description

The invention relates to the oil industry, and in particular to methods of intensifying the displacement of oil from reservoirs that are not uniform in permeability.

The aim of the invention is to increase oil recovery due to an increase in reservoir coverage by flooding.

The method is as follows.

To effectively reduce the water content in the production of producing wells, a small decrease in the water saturation of the formation is sufficient. The reduction in the formation saturation according to this method is achieved by pumping into it a hydrophobic fluid, hereinafter TLU, consisting of 96-98% of a bituminous distillate and 4-2% of an emulsal, which hydrophobizes the water-saturated part of the formation.

as a result, the phase permeability of the reservoir to oil increases, and, consequently, the oil flow rate.

In order to create an impulse of increased pressure and its rapid spread to a considerable depth of the reservoir, it is provided that the injection pressure of the HLM be maintained equal to the pressure of crack opening. With simultaneous injection of the displacing agent through injection wells and TLU through the producing wells, the positive pressure drops are enhanced by the creation of a counter-wave of increased pressure from the producing wells, i.e. due to backpressure.

An increase (increase) in positive pressure drops, in turn, leads to an increase in negative pressure drops.

ABOUT

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pressure at selection. All this ultimately contributes to a more intensive, in comparison with the pulsed method, the redistribution of fluids in an unevenly saturated reservoir, which is aimed at equalizing the saturations and eliminating capillary disequilibrium at the contact of oil-saturated and water-filled zones.

Multiple saturation spikes resulting from the uneven displacement of oil by water from heterogeneous reservoirs create a non-equilibrium state of capillary forces at the contact zones with different saturations. Strengthening alternating pressure drops between zones (layers) of different saturation promotes the acceleration of capillary, countercurrent water impregnation of oil-saturated zones (layers), i.e. the rapid introduction of water from the flooded zones into the oil-saturated along small and oil flows from the oil-saturated zones into the water-driven through large pore channels. All this intensifies the overcoming of the discontinuous nature of the capillary forces, the equalization of saturations, i.e. contributes to the increase in coverage of flooding of heterogeneous reservoirs and an increase in their oil recovery.

Injected TLU, moving along cracks, encounters the counter-pressure of the displacing agent, as a result of which the pressure in them sharply increases, the rate of TLU propagation decreases. This leads to intensive filtration of liquid fluids through the walls of the fracture through the porous water-saturated zones of the formation. In this case, they are hydrophobized, and since TLC has an oil basis, the oil permeability,

As soon as the reservoir pressure in the area of producing wells reaches the value of the initial one, injection of TLU is stopped. And after reaching the initial reservoir pressure in the area of injection wells, the injection of the displacing agent into the injection wells is stopped and the oil is withdrawn. Since the downhole pressure of the operating production wells is significantly less than the crack opening pressure, the injection water does not flow through them, since the cracks in this case are in a closed state. After injection of TLU, there will be no movement of water and over the near-fracture space, as well as along the more permeable, previously water-saturated areas of the formation that are more distant from it.

It is known that the water saturation of reservoirs primarily occurs at the most

permeable, highly porous areas of the formations, which are at the same time weakest in terms of strength, therefore cracks are formed when TJU is pumped into highly permeable and water-saturated parts of the formations. Consequently, during the injection of TLU, the water-saturated, most permeable portions of the reservoir are primarily hydrophobic,

0 through which previously injected into the well injected water. After hydrophobization of the water entry paths into the production wells, the displacing agent will bypass them and advance through the oil-saturated areas of the formations, thereby increasing the waterflood coverage and oil recovery.

When injection of a HLT simultaneously with the injection of a displacing agent, a wave of increased pressure is advanced from

0 producing well to injection wells, contributes to a change in the direction of fluid flow, especially in the area of production wells, which also contributes to enhanced oil recovery of reservoirs.

Thus, the application of this method will allow to achieve simultaneously the following positive effects. Reduce the phase permeability of oil-saturated formations for water and increase it for oil by hydrophobization, and thereby reduce the water-cut of production wells.

Injection of TLU into the layers of mining

5 wells at a pressure equal to the crack opening pressure, simultaneously with the injection of water into the injection well, can enhance the effect of alternating pressure drops, resulting in an increase in reservoir coverage and oil recovery.

A change in the direction of movement of the reservoir and the injected fluid in the area of production

5 wells, which also contributes to the process of increasing the coverage of the reservoirs with water flooding, increasing oil recovery.

As a result of the combined effect of these positive effects, the flow rates of producing wells, both liquid and oil, increase, the coverage of water-flooding and oil recovery increases.

The method is carried out in the following sequence.

5 According to the project, injection and production wells are drilled at the multi-layer oil field. The development is carried out with the help of marginal and in-boundary flooding. Upon reaching a water cut of production wells in the order of 65%, the transition to the use of a pulsed development method.

The production wells located in the zone of influence of each injection are stopped, and injection into injection wells is carried out until the initial reservoir pressure is reached. Then the injection is stopped, the shutter speed is made and the production wells are put into operation. If the production water cut decreased by about 10-15%, then the development is continued in the same way. If the production water cut did not occur at least in some wells, then proceed to the application of this method. At the same time, injection of TLU is carried out only in those wells in which the reduction in water cut has not occurred.

First of all, in these wells, studies are carried out with deep-seated instruments (flowmeter, moisture meter) and the water-saturated zone is determined. The volume of TLU is then determined. required for injection, according to the formula

V 3 (- h m) + 0.5 hi, m3,

where 3 and 0.5 are coefficients taken on the basis of experimental studies;

D is the diameter of the treated water-saturated zone of the reservoir, assumed to be equal to the diameter of the fracture zone during the injection of TLU, m;

h - total perforated thickness of the water-saturated zone, determined by moisture meter, m;

m - fractured porosity of the reservoir,%;

hi - total perforated thickness of seams, m.

After that, go directly to the injection of TLU using the unit. The injection of TLU is performed at a pressure equal to the crack opening pressure. The moment of cracking is marked by a sharp drop in pressure and an increase in fluid flow. Injection is continued until the reservoir pressure reaches the value of the initial reservoir pressure. This moment is determined by measuring static levels at adjacent production wells or directly in the well into which TLU is pumped. In the second case, intermittent injection intervals are made periodically to establish reservoir pressure.

After injection of TLU, the production wells are left under pressure until the end of the injection cycle of the displacing agent in the injection wells. Then they are put into operation. If at the same time the water content of production wells, in

that were pumped TJU, decreased by about 10-15%, then the development of deposits continue with the usual pulse flooding. If the reduction in water cut has not occurred or has occurred by a smaller amount, then continue the application of this method until the above reduction in water cut. Further processing of productive layers of mining

0 squeezers using this method are carried out only in sharply flooded wells. An example. The field was drilled with injection and production wells according to the seven-point scheme. Development

5 was carried out with the help of contour and contour flooding. Take a separate section (element) of a reservoir with production wells Ms 1, 2, 3, 4, 5, 6 located in the zone of influence of the injection well number 7. In the geological section of these wells 5 productive formations were distinguished (from top to bottom ) at; Tue; P; g; d with perforation intervals, respectively, 1619-1621; 1627-1628; 1635.2-1636.8;

5 1637.6-1639.2; 1643.4-1653.2. The flow rates and water cut, the production of these wells were characterized by the data given in table. one.

In connection with the high water production, the well-known pulsed method of acting on the formations by injection was applied. After the operation of the deposit element by this method, for 10 cycles of injection-selection, the flow rates of wells and the production water cut were characterized by the data given in Table. 2

As can be seen from the table. 2, water discharge decreased in wells M 1, 2, 3, 4. Water content remained at the same level

0 only skrzzhinam number 5, 6. In connection with this

these wells were processed

productive layers in this way.

First of all with the help of deep

the moisture meter determined the intervals of water in the 5 saturated zones, i.e. formation intervals from which high-watered production enters the well. Such intervals were in the reservoir g 1638-1639.2 m; in reservoir d 1648.2-1653.2 m. Hence, their total

0 thickness is B. 4 m. Since the injection of HLA takes place at a pressure equal to the crack opening pressure, the hydrophobization of the porous part of the layers will occur mainly through the cracks. Therefore, for

In Figure 5, the average radius of the treated area assumed a crack radius.

It is known that the average radius of crack opening based on the results of direct determinations based on hydrodynamic studies is about 36 m. Hence, the diameter of the cracking formation is 72 m. The average fracture porosity of water-saturated strata is 0.01212% according to the results of laboratory core investigations. Then

h 14 w l 3. (J 4 ° h) 6.4 0.0012 +

+ 0.5 16.4 93.7 +8.2 101.9 m3.

Injection of TLU was carried out at a bottomhole pressure of 38 MPa, i.e. at a pressure that provides crack opening. The duration of injection was determined by the time that the reservoir pressure in the injection site reached an initial pressure of 17 MPa. Since in the wells the values of the parameters included in the formula are close in value, then for both wells the volume of LSM was taken to be the same. Measured flow rate and water cut after injection of TLU into wells No. 5 and 6 had the following data given in Table. 3,

As can be seen from the table. 3, the water cut of products of wells 5 and 6 after the bottom-hole zone treatment decreased by more than 15%. In the remaining wells, a reduction in water cut also occurred, although the processing of the bottomhole zone in them did not produce a well. After 12 injection-extraction cycles, wells 5 and 6 and additionally well 3 were dramatically (20%) flooded. After that, this method was applied again, as a result of which the oil production rate increased by about 1.2 times, while the water cut of each well decreased by approximately 10%. In the future, this method was used every time after a sharp water cut at the production wells.

The main requirement that the hydrophobic liquid must meet is the adsorption of polar components on the rocks. Other significant factors are the degree of condensation of asphalt-resin substances and the thickness of the adsorption films on the solid phase. It is known that, at the beginning of the adsorption process, not only asphaltenes are adsorbed, but also higher resins. 8, asphaltenes are selectively adsorbed, and the higher resins are desorbed. Therefore, the high condensation of asphaltenes should ensure the almost irreversible character of their adsorption.

The above requirements are fully met by some oils, as well as the following hydrophobic solutions: hydrophobic emulsion solutions (GER) based on diesel fuel or industrial oil oils using emulsifiers and stabilizers as used as emulsifiers and stabilizers. sh: x

lime or caustic products containing higher fatty acids (fatty acids and distillation residues during distillation, oxidized petrolatum (SMAD-1), tars

vegetable and animal fats, etc.); anhydrous hydrocarbon-based solutions based on field oils, thickened with fatty acid soaps; hydrocarbon solutions oil soluble

0 surfactants consisting of hydrocarbon liquids (oil, bitumen distillate) and oil-soluble surfactants (emult, neonol). The last type of hydrophobic liquid called

5 TLU is used in this technology.

The benefits of this method are the increase in reservoir coverage by flooding and increased oil recovery. In tab. we give comparative data on

0 results of the operation of the element according to the known impulse method (the results are obtained by calculation) and according to this method (the results are obtained from the actual operation) for the same time 5 276 days. For comparison, only those wells were taken in which the well zone was machined using this method.

As in. One of the table. 4 additional oil production from only two wells

These elements amounted to 2760 m3, which is 18.8% more than the volume of oil produced by the method taken as a prototype. As is known, the oil recovery coefficient is defined as the product of the coverage ratio

5 layers of water flooding and oil displacement.

Since this method, in the first place, provides an increase in the enrollment rate of the waterflood,

0, additional oil can be considered as obtained due to its increase. Based on this, an increase in the oil recovery coefficient at a constant coefficient of displacement compared with the prototype

5 is at least 18%.

Claims (1)

The invention method of development of multilayer oil fields, including the periodic injection into the reservoir of displacing 0 agent through injection wells and periodic product selection through production wells, characterized in that, in order to increase oil recovery by increasing reservoir coverage by flow, simultaneously with the injection of water into injection wells, hydrophilicating fluid is pumped into high-level production wells located in the zone of influence of injection SKELS, and the injection of water-repellent liquids are conducted at the pressure of cracking and until the pressure in the treated area reaches the initial formation pressure, while the injection of the hydrophobic fluid during the development process is periodically repeated after a sharp increase in the production water-cut. Table 1 table 2 Table 3 Table 4 Total2760m3