SU1756545A1 - Method for developing oil field composed of non-uniform layered beds - Google Patents

Abstract

The invention relates to the development of oil fields with the injection of reagents and m. applied on reservoirs, presented in layers and zonal heterogeneous reservoirs. The goal is to increase oil recovery by increasing the coverage of low-permeability zones of the reservoir. To do this, after drilling the field in areas with weak hydrodynamic coupling between production and injection wells, additional injection wells are placed at a distance greater than the area of capture of the main injection well when it co-operates with an additional one. Chemical reagent is pumped into additional wells before its main injection wells pass in a volume sufficient to treat the highly permeable formation zone. Displacement agent is pumped into the main injection wells and simultaneously chemical reagent is injected into additional injection wells in a volume sufficient to process the low permeability zone of the formation. 3 silt SL

Description

The invention relates to the development of oil fields with the injection of reagents and can be applied to deposits represented by layer-zonal heterogeneous reservoirs.

There is a method of developing a gas condensate reservoir with non-uniform reservoirs, by pumping water into high-permeability zones, pumping separated gas through injection gas wells into low-permeability zones before breaking through water and dry gas into production wells, after which the injection gas wells are transferred into production and depletion of the deposit is depleted

There is also a known method of developing an oil field, according to which a field is drilled with rows of wells, injects a displacing agent into the main, TXTHM reagent into additional injection wells located between a number of injection wells and the closest to it a number of producing wells, and There are oil recovery through production wells.

The disadvantage of these methods is that under conditions of a non-uniform reservoir, the injected fluids are filtered only at a certain part of the object, and the penetrating zones of the reservoirs due to the large filtration resistance in the general area.

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the reservoir system remains uncovered.

The closest in technical essence to the present invention is a method according to which a layer-by-layer non-uniform field is drilled with a grid of production and injection wells; create independent channels with layers; inject the displacing agent into the highly stratified formation, and the reagent into the low-permeable formation; then the reagent and the displacing agent are pumped into the formation with lower permeability with the injection pressure less than the injection of the displacing agent into the high-permeability formation.

This method achieves the goal of increasing the coverage of a low-permeable reservoir with exposure in a layered-non-uniform field.

A significant disadvantage of this method is that under the conditions of layer-by-layer non-uniform deposit, i.e. when a change in the permeability of the layers is observed both in the well section and in the field area, the low-permeable zones of the individual layers remain uncovered by the impact. The injection of the vortexing agent into a highly permeable reservoir creates conditions in it (high reservoir pressure) that do not allow it to be covered with a fully injected reagent.

The aim of the invention is to increase oil recovery by increasing the coverage of the impact of low-permeability zones of the reservoir.

This goal is achieved by the proposed method, including drilling it with a uniform project grid of production and injection wells, determining the hydrodynamic relationship between production and injection wells, injecting a displacing agent into the highly permeable zones of the reservoir and chemical reagent - into less permeable, the latter is pumped at less than displacing agent, product selection from production wells.

New is that. that in areas with a weak hydrodynamic connection between production and injection wells, additional injection wells are placed at a distance greater than the capture region of the main injection well during its joint operation with an additional one; chemical reagent is pumped into additional wells before the main injection wells pass through sufficient to process the highly permeable zone of the formation, and the injection fluid is pumped into the main injection wells and simultaneously Injection of chemical reagent into additional injection wells in a volume sufficient to treat the low-permeability zone of the formation.

Figure 1 presents the scheme of layer-by-zone heterogeneous deposits (selection

products from all wells), figure 2 - scheme of the same hack (entry of additional injection wells, the injection of reagent into it and the selection of products from the remaining wells); FIG. 3 is a schematic of the same reservoir (injecting a displacing agent into the main injection well at a pressure greater than that in addition when reagent is injected, and product selection).

1 to 3 are shown; 1 and 2 - respectively, the main and additional injection wells; 3 and 4 - production wells.

The method is carried out in the following sequence.

5 The field, represented by layer-zonal non-uniform reservoirs, is drilled with a project grid of production and injection wells and is being repaired. Production of products from production wells is carried out. During drilling and operation, wells are examined, reservoir parameters are determined, and flow rates are measured. Build map development

5 and geological profiles between wells. High and low permeable formation zones are determined.

The proposed method is considered on the example of a reservoir of oil, including one injection well and two production wells. The wells opened two formations that differ in permeability both in the section and in area (see Fig. 1). The lower layer has a worse reservoir characteristic than the upper one. Well 3, due to lower permeability, has a lower flow rate than well A. According to the designed development system, it is planned to inject into the reservoir

0 displacing agent (water, gas, etc.) and to increase the oil recovery factor — a chemical reagent (solvent, steam, surfactant, etc.) of the calculated volume.

Based on well survey results

5 begin to use the proposed method.

At the calculated distance from the main injection well, in the low permeable part of the formations, an additional well 2 is placed. This well may be

specially drilled, returned from other horizons, etc. Arrangement is made and a reagent is pumped into it.

When the reagent is pumped, the filtration flow is formed depending on the reservoir characteristic of the formations. In accordance with the heterogeneity of permeability oil displacement occurs. The injected reagent is largely filtered by the highly productive part of the formations. Production well is selected from well 1.

After the injection of the calculated volume of the reagent and its passage through the well 1, the latter is transferred to the injection of the displacing agent i with a injection pressure greater than the operating pressure in the additional well. In this case, the maximum reservoir pressure will fall on the high-filtering part of the formation.

The created area of increased reservoir pressure becomes the flow section with the boundary that allows cutting off part of the reagent that is filtered through the highly permeable part of the formation. Another part of the injected reagent is directed towards low-permeability zones of the formations. As the reagent is pumped throughout the section of the productive part of the formations, it covers the entire volume of the reservoir.

If necessary, again to cover a high-permeable formation with a reagent, the injection of the displacing agent into an additional injection well is carried out at a lower or equal pressure from the main one. Creating a reservoir pressure of the required value in the high-filtering part of the reservoir in the injection zone of the main injection well allows controlling the movement of the reagent with the displacing agent in a given direction.

When pumping under high pressure into the well 1, the flow separation boundary between the displacing agent and the reagent lies between the wells. When pumping a displacing agent, a capture area of well 1 is created (see FIG. 3). Therefore, well 2 needs to be placed at a certain distance so that the capture area of well 1 does not go beyond well 2. Otherwise, the injected reagent will be completely sent to well side 4.

The sequence of operations considered is eligible for the initial displacement of oil with a reagent. If, however, a displacing agent has already been injected into the reservoir into the main injection well, the injection into it must be stopped and the reservoir reduced.

pressure in the high-permeable part of the formation to a value less than that in low-permeable areas or equal to it. The operation to create increased reservoir pressure in high-permeable areas of the reservoir, in any case, should be performed only after the injection of the reagent.

Example. The implementation of the proposed method is considered on the example of a layer-zoned non-uniform oil deposit (see Fig. 1) drilled with three wells: one injection and two producing. Well spacing is 500 m.

The wells opened two oil-bearing saturated reservoirs with an average permeability, respectively, of the upper (reservoir a) 0.750 microns, the lower (reservoir 6} 200 microns.

The permeability of the formations in wells 3 and 4 is, respectively, plzsta and 0.200 and 1.30 μm2; formation b 0,100 and 0,300

m

um It can be seen from the above data that the plot is layer-zoned heterogeneous. The average oil saturated thickness of a highly permeable formation is 5.0 m. Bottom 2.0. The deposit is saturated with oil at a viscosity of 150 mPa-s. The balance reserves of the site are 800 thousand tons. After drilling the site, the well was put into operation with anhydrous oil.

Investigations (hydraulic interception, test injection) have shown that between wells 1 and 3 a weak hydrodynamic coupling is observed. The injectivity of the lower layer b is 9.5 times less than that of the layer a.

An additional injection well 2 was drilled at the calculated distance (100 m) from the main injection well in the low-permeable part of the formation (see Fig. 2).

The distance at which it was necessary to introduce an additional injection well was determined by mathematical modeling of the reservoir system at given downhole pressures in the injection wells and the resulting capture zone of the well 1.

According to the technological scheme of field development, a wide fraction of light carbon (NGL) in the amount of 2% of the pore volume or 28 thousand meters should be injected into the reservoirs of the considered area. WFLH was pumped into well 2 only in a volume of 12.8 thousand m2, corresponding to 2% of the pore volume of the highly permeable part of the formation, and then switched to water injection with a discharge pressure of 12 MPa (design pressure).

When solvent appeared in well 1, product selection was stopped. After passing the solvent through it, well 1 was introduced under water injection with a discharge pressure of 13-15 MPa. Water injection in well 1 in a volume of 110–115% of fluid withdrawal under reservoir conditions was carried out within 4 months, which made it possible to exceed reservoir pressure measured in well 2 by 2.0 MPa. Then, simultaneously with injection in well 1, the rest of the reagent was injected into well 2 (15.2 thousand m2).

As studies have shown, the simultaneous injection of the reagent into the well 1 and the displacing agent into the well 1 made it possible to cover the low-permeable zones of the layer-zonal non-uniform deposit with the action. The coefficient of seam coverage by impact was 70%, which is 12.4% more than by the known technology (see table).

Additional oil production for the entire period of operation of the site is 72 thousand tons.

Claims (1)

Invention Formula A method for developing an oil field composed of layer-zonally inhomogeneous strata, including the equalization of its uniform design a grid of production and injection wells, the definition of a hydrodynamic connection between production and injection wells, the injection of a displacing agent into highly permeable zones of the reservoir and a chemical agent into low permeability under pressure less than the displacing agent, the selection of products from producing wells that differ in volume. that, in order to increase oil recovery by increasing the coverage of low-permeability zones of the reservoir, in areas with a weak hydrodynamic connection between production and injection wells, additional injection wells are placed at a distance greater than the capture area of the main injection well during its joint operation with an additional one wells chemical reagent to the passage of its main injection wells in a volume sufficient to handle highly permeable zones formation is performed in the main injection injectors displacing agent and at the same time the chemical reagent is injected into the additional injection wells in a volume sufficient to Obra Botko low permeability formation zone. Ko / in Coverage ratio Kach & . Oil recovery factor, K tso Kotv,% Recoverable reserves, Qo Qfi Kno, thousand tons Additional oil production, thousand tons 70 70 49 392 72 LVA 3 CAPTURE AREA t CONDITIONAL ARRANGEMENTS: -1 low density | Jvysonopronmiashy mon st - - RSA-Gent download Vanachka. withdrawing agent Doma production -f zone increased pstostoy + pressure VA Fig. 2 Fig. five