RU2431038C1 - Procedure for development of deposit of oil in layerd reservoirs - Google Patents

Abstract

FIELD: oil and gas production. ^ SUBSTANCE: procedure consists in determination of pays divided with impermeable clay interlayers, and in driving main horizontal boreholes in middle of pay. Above and below the pay there are drilled horizontal laterals along producing interlayers. According to the invention impermeable clay interlayers are shut off with profile shutters. Also, hydraulic or acid break is carried out in each horizontal bore of producers before their bringing into service. Hydraulic break in terrigenous reservoirs is performed successively downright, while hydraulic acid break in carbonate reservoirs is carried out successively bottom-up. ^ EFFECT: raised efficiency of development due to increased sweep of reservoirs, reduced expenditures for construction and simultaneous extraction of stock from several interlayers. ^ 1 ex, 1 dwg

Description

The invention relates to the oil industry and may find application in the development of oil deposits in layered carbonate reservoirs.

A known method for the development of oil deposits in layered carbonate reservoirs (RF patent No. 2305758, IPC E21B 43/14, publ. 09/10/2007, bull. No. 25), including the selection coinciding in terms of the upper reservoir in carbonate reservoirs with effective oil-saturated thicknesses of not less than 3 m and the lower massive reservoir with total oil-saturated thicknesses of more than 15 m, a profile shutter is installed between the allocated deposits, the casing is lowered to the roof of the lower reservoir with a filter in the productive part of the upper reservoir, the annulus is cemented equipment, open the upper production interval, lower two elevators, drill vertical and / or directional or branched horizontal injection wells in accordance with the design grid. Place horizontal trunks of injection wells parallel to the plane of horizontal trunks of production wells. In the presence of sanitary protection zones and oil-saturated thickness of the reservoir of the upper reservoir of more than 5 m, a multi-hole horizontal well is to be drilled. The injection of the working agent is carried out cyclically in the upper and lower deposits during their simultaneous and separate operation.

The disadvantage of this method is that in conditions of heterogeneous multilayer, when several thin layers of reservoirs coincide in plan, some of them remain undeveloped. This leads to a decrease in the efficiency of field development.

Closest to the proposed invention in technical essence is a method of developing an oil deposit in layered carbonate reservoirs (RF patent No. 2387815, IPC EV 43/20, publ. 04/27/2010, bull. No. 12), including the placement, drilling of vertical injection and branched horizontal production wells with horizontal shafts, injection of displacing fluid through vertical injection wells and product selection through a branched horizontal production well. At least two thin carbonate reservoirs are identified that coincide in plan, are located in close proximity to each other, separated by clay interlayers, we specify the distribution of oil-saturated thicknesses of reservoirs by reservoir area, select areas with the maximum allowable effective oil-saturated thicknesses of reservoirs - reservoirs of at least two meters each, then a branched horizontal well is drilled to simultaneously develop two or more reservoir layers, place horizontally tal trunks in most permeable formations intervals, wherein the barrels is carried out in the direction of increasing net pay thickness, and length of trunk take inversely proportional to their permeability.

The disadvantage is that with this method of development, a significant part of the wellbore is lost in unproductive bridges, the formation is not sufficiently covered by the impact.

The technical tasks are to increase the coverage of formations by developing horizontal and vertical oil reserves by drilling a branched horizontal well and conducting hydraulic fracturing, increasing oil recovery, increasing the efficiency of developing oil deposits in layered reservoirs, increasing the flow rate of wells, reducing the cost of constructing additional wells by simultaneously producing reserves from several layers, increase in coverage of layers due to hydraulic fracturing or hydroacid the gap.

The technical problem is solved by the method of developing an oil deposit in layered reservoirs, including the allocation of productive formations separated by impermeable clay interlayers, the conduct of the main horizontal trunks in the middle of the reservoir, and above and below horizontal branches along the productive interlayers.

What is new is that impermeable clay interlayers are covered by profile overlaps, and in each horizontal well of production wells, before putting them into operation, hydraulic fracturing or hydro-acid fracturing is carried out, while in terrigenous reservoirs hydraulic fracturing is carried out successively from top to bottom, and in carbonate reservoirs, hydro-acid fracturing sequentially from bottom to top.

SUMMARY OF THE INVENTION

The development of oil deposits in layered carbonate reservoirs is characterized by reservoir coverage by the development of oil reserves. The proposed method solves the problem of increasing the coverage of formations by the development of oil reserves, increasing oil recovery, increasing the efficiency of developing oil deposits in layered reservoirs, increasing well production rates, reducing the cost of constructing additional wells by simultaneously developing reserves from several layers.

The drawing shows a section of an oil deposit in a layered reservoir, where:

1 - the main trunk of a horizontal branched production well; 2 - horizontal branches; 3 - impermeable clay interlayers; 4 - productive layers; 5 - oil reservoir.

The method is carried out in the following sequence.

An oil reservoir of 5 in layered reservoirs is drilled with a rare grid of vertical wells. Clarify the geological structure of the reservoir, build maps of effective oil-saturated thicknesses, conduct core studies, determine porosity, permeability. Carbonate productive layers separated by impermeable clay interlayers are distinguished 3. The distribution of oil-saturated thicknesses of productive interlayers 4 is determined by reservoir area 5. Select areas of reservoir 5 within which at least two productive interlayers can be distinguished 4. Hydrodynamic modeling of the field development process is carried out. Next, at least one branched horizontal production well 1 is drilled for the simultaneous development of several productive layers 4. In this case, the main horizontal wellbore 1 is held in the middle of the productive formation 5, and the horizontal branches 2 are above and below the main wellbore 1 along the corresponding productive interlayers 4. Separate operation economically inefficient, and when drilling a purely horizontal well, a significant part of it is lost in unproductive bridges.

Clay impermeable interlayers 3 between productive interlayers 4 are overlapped by profile overlaps.

Next, before putting into operation production wells 1 in each of the horizontal shafts 2, hydraulic fracturing or hydro-acid fracturing is performed to increase the productivity of the wells. Hydraulic fracturing or acid fracturing will allow the acid to penetrate into the low-permeability zones 3 and clean the pores of the collector 4 of insoluble mechanical particles, which will combine the productive layers 4 and reservoir 5 into a single system and will lead to the drainage of the entire volume of the reservoir 5.

Hydraulic fracturing or acid fracturing is carried out in all horizontal trunks 2 of the producing well 1 simultaneously or sequentially, from top to bottom or from bottom to top, depending on the type of reservoir. Moreover, in terrigenous reservoirs, hydraulic fracturing is performed, and in carbonate reservoirs, hydraulic acid fracturing is performed.

In terrigenous reservoirs, hydraulic fracturing is carried out starting from the upper horizontal trunk 2 to the lower horizontal trunk 2, due to the instability of the rocks of terrigenous reservoirs and the exclusion of their shedding under the influence of overlying rocks.

In carbonate reservoirs, hydraulic fracturing or hydroacid fracturing is carried out from the bottom up, as a result of which the permeability of the non-massive formations increases.

In all massive type reservoirs, hydraulic fracturing or acid fracturing is carried out simultaneously through each horizontal wellbore 2 of a branched production well 1.

Then the well 1 is mastered and put into operation. Produce oil from a branched horizontal production well 1.

Concrete example

They are developing a section of the oil deposit 5 of the Verey horizon. The site was drilled with producing and injection wells on a sparse grid, equipped.

On the oil deposits 5 allocated a plot with three productive layers 4, which are in close proximity to each other. Effective oil-saturated thicknesses of the interlayers 4 are on average (top to bottom) 4.5 m, 3.5 m, 2.8 m. They are separated by clay interlayers 3, the average thickness (top to bottom) is 3.8 m and 3.4 m The permeability of the lower productive layer is 0.121 μm ² , the average layer is 0.42 μm ² , the upper layer is 0.82 μm ² . Next, they drill one branched horizontal production well 1 with a length of 300 m for the simultaneous development of several productive layers 4. In this case, the main horizontal trunk 1 is carried out in the middle of the productive formation 4, and the horizontal branches 2 are above and below the main shaft 1 along the corresponding productive layers 4. Length each horizontal trunk is 150 m and 200 m, respectively. Clay-impermeable interlayers 3 between productive interlayers 4 are overlapped by profile overlaps.

Next, before commissioning the production wells 1 in each of the horizontal shafts 2, hydraulic fracturing or hydro-acid fracturing is performed. Hydraulic fracturing or acid fracturing will allow the acid to penetrate into the low-permeability zones 3 and clean the pores of the collector 4 from insoluble mechanical particles.

Then the well 1 is mastered and put into operation. Produce oil from a branched horizontal production well 1.

During the development of the entire interval, the coverage of the formation with respect to the closest analogue increases, oil recovery increased by 30%, the actual oil production rate increased by 1.5 times, additional oil production increased by 70% due to the simultaneous operation of several layers.

The application of the proposed method will increase the coverage of formations by developing oil reserves horizontally and vertically by drilling a branched horizontal well and conducting hydraulic fracturing, increase oil recovery, increase the efficiency of development of oil deposits in layered reservoirs, increase the flow rates of wells, reduce the cost of constructing additional wells due to the simultaneous development of reserves from several interlayers, increase the coverage of interlayers by exposure due to hydraulic fracturing or hydroxy acid rupture.

Claims (1)

A method of developing an oil deposit in layered reservoirs, comprising isolating productive formations separated by impermeable clay interlayers, conducting main horizontal trunks in the middle of the productive stratum, and horizontal and lateral branches along productive interlayers are carried out above and below it, characterized in that the impermeable clay interlayers are covered by profile overlapping, moreover, in each horizontal well of production wells before putting them into operation, hydraulic fracturing or acid fracturing is carried out, this, in terrigenous reservoirs, hydraulic fracturing is carried out sequentially from top to bottom, and in carbonate reservoirs, hydraulic fracturing is sequentially from bottom to top.

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