RU2454533C1 - Development method of non-homogeneous oil deposit at late stage of development - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: development method of non-homogeneous oil deposit involves drilling of production and injection wells, flooding of formation from injection wells and oil extraction to the surface via production wells. Geological structure is checked, various structural zones of deposit are determined as per results of drilling and simulation. Additional new shafts of production wells are drilled based on the zones determined. Deposit is divided in zones concerning levels of its roof location. At that additional wells are drilled as vertical shafts in zones of maximum pitch of roof, the shafts are used for production. Wells of old pattern located in these zones are used as certain production and injection wells. Besides before start of extraction in additional and certain production wells, hydrostatic level of liquid column measured from deposit roof in these wells and level of oil-water contact (OWC) are determined. At that production is performed below OWC level; upon production hydrodynamic layer in additional wells is maintained in lower third part of hydrostatic level and in certain wells - in the middle third part.

EFFECT: improving efficiency of development of non-homogeneous deposits, increasing oil removal and increasing flow rate.

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Description

The invention relates to the oil industry and may find application in the development of a heterogeneous oil field at a late stage of development.

A known method of a heterogeneous oil field (RF patent No. 2259474, IPC E21B 43/20, published on 08.27.2005), including drilling injection and production wells, waterflooding and extracting oil to the surface, refinement of the geological structure according to the results of drilling and modeling and drilling additional wells with a horizontal wellbore or horizontal wellbores from old wells, whereby the location of the boundaries of the reservoir replacement zones is determined, the amount of fixed oil concentrated in the vicinity of the displacements of collectors is then carried out to drill horizontal holes from older wells located near the boundaries of reservoir zones of substitution, and / or new wells with horizontal barrel in this area, and horizontal stems are drilled in a direction perpendicular to the border zone of substitution.

The disadvantages of the method are the possibility of erroneous calculation of the volume of mobile oil near the zones of replacement of the reservoirs, insufficient efficiency of the development system due to inaccurate determination of the direction of drilling horizontal wells, insufficient coverage of the formation by the impact.

Closest to the proposed invention in technical essence is a method of developing a heterogeneous oil field (RF patent No. 2371571, IPC E21B 43/20, publ. 10/27/2009), including drilling injection and production wells, waterflooding and extraction of oil to the surface, refinement of the geological structures according to the results of drilling and modeling, as well as the drilling of horizontal wells from old wells, while determining the location of the boundaries of zones of different permeability of the layers, after which from old wells closest to Ones with high permeability of the formation and located in the zone with low permeability of the formation, drill horizontal shafts directed towards zones with high permeability of the reservoir, then lateral shafts are drilled from these horizontal shafts in the zone of high permeability of the reservoir and exploit these wells as production wells until the production rate decreases oil below economic profitability, after which they are transferred to injection, and from wells located in the zone with low permeability of the reservoir and the most remote from zones with high permeability new formations, horizontal wells are drilled covering the perimeter of the zone with high permeability of the formation, and these wells are operated as injection wells.

The main disadvantages of this method are the difficulty in its implementation, the insufficient efficiency of field development, the possibility of erroneous calculation of the volume of oil in productive formations.

The technical tasks are the development of residual reserves from the most productive sections of the field, increasing the efficiency of developing a heterogeneous field and oil recovery due to the efficient operation of the stock of production and injection wells, ensuring economic profitability, increasing the life of the wells, optimizing the location of wells, and increasing the volume of produced products.

The technical problem is solved by a method of developing a heterogeneous oil field at a late stage of development, including drilling injection and production wells, flooding the reservoir from injection wells and extracting oil to the surface through production wells, clarifying the geological structure with the determination of various structural zones of the field according to the results of drilling and modeling, drilling new additional production wellbores based on certain zones, the operation of certain production wells yn old stock to reduce the oil flow value lower than economically viable, followed by their transfer into the injection wells and wellbores operation covering the perimeter area to be used for production of products as injection wells.

What is new is that the field is divided into zones based on the location of its roof, with additional wells being drilled in the form of vertical shafts in the areas of maximum roof lift, which are used to produce products, and the old grid wells falling into these zones are used as certain production wells and injection wells, moreover, before starting additional and specific production wells for production, the hydrostatic level of the liquid column is measured from the roof of the field in these wells x, and the level of water-oil contact (WOC), while production is performed below the level of the WOC, and in additional wells, the hydrodynamic level during production is maintained in the lower third of the hydrostatic level, and in certain wells in the middle third.

SUMMARY OF THE INVENTION

The development of a non-oil field is characterized by low oil recovery. The proposed method solves the problem of developing residual reserves from the most productive sections of the field, increasing the efficiency of developing a heterogeneous field and oil recovery through the efficient operation of the production and injection wells, ensuring economic profitability, increasing the life of wells, optimizing the location of wells, and increasing the volume of produced products.

Figure 1 presents the implementation diagram of the proposed method for developing a heterogeneous oil field at a late stage of development, where 1 - additional vertical production wells; 2, 3 - certain production and injection wells of the old stock; 4 - VNK.

Figure 2 plot of a heterogeneous oil field (top view), where 1 is an additional vertical well; 2, 3 - certain production and injection wells of the old stock; 5 - section of a heterogeneous oil field; 6 - zone of domed uplifts.

The method is carried out in the following sequence.

A heterogeneous oil field 5 is drilled with a design grid of 2 production and 3 injection wells. Water is injected into injection wells 3 and oil is extracted from production wells 2.

After reaching the maximum water cut of the well products, the geological structure of the site of the heterogeneous oil field 5 is clarified, various structural zones are determined by drilling results, and the heterogeneous oil field is modeled. Deposit 5 is divided into zones based on the location of the roof. Determine the level of oil-water contact (MIC).

According to the depletion of oil reserves in the reservoir, dome-shaped uplifts 6 are distinguished between the wells of the old stock 2 and 3, exceeding the absolute marks on the roof with the definition of oil saturation boundaries.

Next, new additional shafts of vertical production wells 1 are drilled in the zone of dome-shaped elevations 6 with a maximum amplitude mark on the roof so that the pump inlets are located below the level of the oil-water contact (WOC) 4. Seal the design grid of wells 2 and 3.

Production wells of the old fund 3, located along the perimeter of the reservoir, are exploited until the maximum water cut of the production of wells is reached and the oil production rate decreases below an economically viable value, then they are transferred to injection wells.

Certain wells 2 located close to the zone of the dome part 6 are transferred from injection wells to production wells.

Water is injected into injection wells 3.

Before putting into operation new additional wells 1 and certain production wells 2 of the old foundation, the hydrostatic level of the liquid column is determined.

Wells 1, 2, 3 are put into operation, and in new additional wells 1, the hydrodynamic level during production is maintained in the lower third of I from the hydrostatic level, and in certain wells 2 and 3 of the old stock in the middle third of II.

First, intensive water is sampled from the sampling zone, as a result of which the oil from sections 7 is pulled to the trunk of new additional wells 1 as water is taken after the level of oil-and-gas oil drops below the sampling zone in the well. As a result, oil selection begins. This contributes to additional oil production from undeveloped sections between wells 2 and 3.

Concrete example

The site of the heterogeneous oil field 5, represented by deposits of the Tournaisian stage, is drilled with a design grid of production 2 and injection wells 3 with a distance between wells of 500 m. Water is injected into injection wells 3 in the amount of 13.9 thousand m ³ and oil is extracted from production wells 2 The geological and physical characteristics of the Tournaisian stage are presented in the table.

Upon reaching water cut of well production of 90-95%, the geological structure of the site of the heterogeneous oil field 5 is specified, the boundaries of the oil saturation are determined, and a hydrodynamic model of the heterogeneous oil field is built. Deposit 5 is divided into zones based on the location of the roof. Determine the level of VNK 4. The absolute elevation of VNK takes values depending on the location of productive formations from -923 m to -949 m (see table).

Table Options Tournaisian Average depth, m 1256.2 Type of deposit massive Collector type pore fissure The average effect. oil saturation. thickness m 10,2 Porosity,% 12 Permeability, × 10 ^-3 μm ² 34 Initial formation temperature, ° C 25 Initial reservoir pressure, MPa 10.73 Oil viscosity in reservoir conditions, MPa · s 61.3 The density of oil in reservoir conditions, t / m ³ 903 Absolute mark of VNK, m from -923 to -949 Productivity coefficient, × 10 m ³ / day · MPa 0.451

Allocate dome-shaped uplift 6 between the wells of the old stock 2 and 3, exceeding the absolute marks on the roof with the definition of the boundaries of oil saturation.

Inside the oil content circuit at a distance of 250 m from the wells of the old foundation 2, 3, additional additional shafts of vertical production wells 1 are drilled so that the pump inlets are located below the level of the oil-water contact (WOC) 4 in the area of dome-shaped elevations 6.

Production wells of the old fund 3, located along the perimeter of the reservoir, are exploited until the water production of the wells reaches 98% and the oil production rate drops below 2.5 tons / day, then they are transferred to injection wells.

Certain wells 2 located close to the zone of the dome part 6 are transferred from injection wells to production wells.

Water is injected into injection wells 3.

Before putting into operation new additional wells 1 and certain production wells 2 of the old foundation, the hydrostatic level of the liquid column is determined.

Wells 1, 2, 3 are put into operation, and in new additional wells 1, the hydrodynamic level during production is maintained in the lower third of I from the hydrostatic level, and in certain wells 2 and 3 of the old stock in the middle third of II.

First, intensive water is sampled from the sampling zone, as a result of which the oil from sections 7 is pulled to the trunk of new additional wells 1 as water is taken after the level of oil-and-gas oil drops below the sampling zone in the well. As a result, oil selection begins. This contributes to additional oil production from undeveloped sections between wells 2 and 3.

During the development of the entire interval, the coverage of the formation with the impact increases, oil recovery increased to 30%, the well operating time increased to the maximum water cut, additional oil production amounted to 200 thousand tons of oil.

The application of the proposed method will allow the most efficient development of heterogeneous deposits, the involvement of residual oil reserves in the development, increase oil recovery due to the efficient operation of the stock of producing and injection wells, increase well production rates, increase well life, increase production volumes.

Claims (1)

A method of developing a heterogeneous oil field at a late stage of development, including drilling injection and production wells, waterflooding from injection wells and extracting oil to the surface through production wells, clarifying the geological structure with the determination of various structural zones of the field according to the results of drilling and modeling, drilling of new additional shafts production wells based on certain zones, the operation of certain production wells of the old stock to a decrease in oil bits below an economically viable value, followed by their transfer to injection wells and the operation of wellbores, covering along the perimeter the zone used for production as injection wells, characterized in that the field is divided into zones based on the levels of its roof, with additional wells they drill in the form of vertical shafts in the areas of maximum roof lift, which are used for production, and the old grid wells falling into these zones are used as isolated production and injection wells, moreover, before launching additional and specific production wells for production, the hydrostatic level of the liquid column measured from the roof of the field in these wells and the level of water-oil contact (VOC) are determined, while production is performed below the level of the VOC, and in additional wells, hydrodynamic production level is maintained in the lower third of the hydrostatic level, and in certain wells in the middle third.

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