The way to develop heterogeneous permeability oil reservoirs

 

The invention relates to the field of the oil industry, and in particular to methods of development of oil fields with heterogeneous permeability layers using physico-chemical methods of enhanced oil recovery. Improves the efficiency of the development of layered heterogeneous permeability oil reservoirs with the use of aqueous polymer solutions. The inventive method includes dual injection through injection wells rims of the polymer solution, followed by displacement of water. The interlayer is less permeability is taken for the base. The polymer is not obtained. The volume and viscosity of polymer solutions injected into the other layers, select from the clearing conditions fluid flow resistance so that the moment of their approach to the production wells coincided with the moment of the approach of the displacement front in the underlying interlayer. Volumes rims and viscosity of polymer solutions injected into the other layers, determine the rate of change of speed of movement of the displacement fronts in each of the layers so that their fronts are suited to the production wells simultaneously with the displacement front in the base group relates to the field of oil industry, namely, the way of the development of oil fields with heterogeneous permeability layers using physico-chemical methods of enhanced oil recovery.

There is a method of designing heterogeneous permeability oil reservoirs, which consists in injecting into the reservoir an aqueous solution of polymer with high viscosity [M. L. Surguchev Secondary and tertiary methods of enhanced oil recovery". M.: Nedra, 1985, pp. 165-175].

At the displacement front is reduced viscous instability, and when pumping through a single filter, the volume of the rim is distributed in layers in proportion to their pickup. Larger volume enters the high permeability layers and largely increases the filtration resistance that ultimately, it is believed, leads to the alignment of the displacement front and expanding reservoir flooding. On the basis of experimental data optimal amount rims considered to be in the range of 0.2-0.3 of the pore volume of the reservoir when the weight of the polymer concentration of 0.05%.

The disadvantage of this method is often premature water breakthrough through highly permeable interlayer, when the viscosity of the solution and resistance factor becomes plastome high permeability, which consists in injecting into the reservoir an aqueous solution of the polymer with the addition of the thickener [A. S. USSR 1837104, IPC6E 21 IN 43/20]. This way you can prevent premature breakthrough of injected water in highly permeable interlayers.

The disadvantage of these methods is that viscous solutions of polymers substantially block the low permeability layers.

The prototype is the way to develop heterogeneous permeability oil reservoirs, which is dual injection through injection wells rims of polymer solutions followed by pushing them with water. In high-permeability layers inject solutions of polymers of high molecular weight and low-permeability layers - solutions of polymers of low molecular weight with respect to the conditions that the average size of the macromolecules of the polymer injected into the interlayers, was less than the average diameter of the pore channels [RF patent 2095555, IPC6E 21 IN 43/22].

The disadvantage of the prototype is that the injection of the polymer solution even low molecular weight in the low permeability layers reduces the rate of oil production from the formation, thereby reducing the overall rate of production.

NEA for high-permeability layers. This leads to increased consumption of reagents, and the overall pace of development is reduced.

The present invention aims at improving the efficiency of the development of layered heterogeneous permeability oil reservoirs with the use of aqueous polymer solutions.

The result is achieved that the way to develop heterogeneous permeability oil reservoirs, including dual injection through injection wells rims of the polymer solution, followed by displacement of water, the formation of lower permeability are taking over the base, in which the polymer is not obtained, and the volume and viscosity of polymer solutions injected into the other layers, select from the clearing conditions fluid flow resistance so that the moment of their approach to the production wells coincided with the time coincided with the moment of the approach of the displacement front in the underlying interlayer, with the amounts of rims and viscosity of polymer solutions injected into the other layers, determine the rate of change of speed of movement of the displacement fronts in each of the layers so that their fronts are suited to the production wells simultaneously with the displacement front in the underlying interlayer in a particular GE the thieves type and concentration of the polymer is determined on the basis of the data on its rheological and filtration characteristics, obtained on core samples extracted from the interlayers.

The method is as follows. For the selected area oil fields, presents a layered-inhomogeneous layer on the core samples previously examined their filtration characteristics. In accordance with the reserves and profitability generation choose the seams with low permeability, which take over the base. Then estimated by taking into account the state of development at specific geo-physical conditions determine the necessary changes in fluid flow resistance of the high-permeability layers of the conditions concurrent with the deposition of the interlayer approach fronts displacement to the production wells. From the obtained characteristics of the movement as a first approximation to determine the minimum volume of the rims so that between the front and rear edges of the rims of similar interlayers do not have any gap. Having volumes rims, choose the types of polymers on their rheological characteristics so that the flow of polymer from the high permeability of the formation in the less permeable was the most difficult due to the abrupt change of the resistance factor. Having volumes of fringes in the second approximation, the s method were tested in a model of layered heterogeneous reservoir. The model is made of transparent material, its length 1.6 m, height of 0.36 m, width 0,035 m Porous medium - ground quartz sand. The reservoir was modeled three hydrodynamically linked layers with a thickness of 0.12 m, the Permeability of the low permeability of the formation of 0.4-0.5 μm2and high permeability is from 1.2 to 2 μm2. The deposition of the interlayer was sandwiched between highly permeable. Used polymer Accutrol-623 (M=5106). As a solvent for polymers and for eviction was used tap water. As the oil used oil horizon D1Romashkinskoye field. The displacement of the primary. Displacing water and polymer solutions were pumped into the reservoir from separate containers in each interlayer, the selection of fluid produced from each of the interlayer. The movement of the fronts of the displacement was controlled visually by the introduction of the color indicator. The results of the experiments are shown in the table.

The experiments showed that injection of a solution Accutrol-623 volume of 0.3 of the total pore volume of the reservoir in the deposition of the interlayer pumped smaller part of the whole solution mainly injected into the high permeability layers. However, even a small about what byte 2 in the deposition of the interlayer polymer is pumped. In high-permeability layers it took to upload rims from 0.1 pore volume of the reservoir, the rate of production in comparison with experiment 1 increased 1.6 times and was obtained self-similar mode of movement of the displacement fronts. Due to the increase in coverage has increased anhydrous development and ultimate oil recovery.

Claims

1. The way to develop heterogeneous permeability oil reservoirs, including dual injection through injection wells rims of the polymer solution, followed by displacement of water, characterized in that the interlayer is less permeability is taken for the base, in which the polymer is not obtained, and the volume and viscosity of polymer solutions injected into the other layers, select from the clearing conditions fluid flow resistance so that the moment of their approach to the production wells coincided with the moment of the approach of the displacement front in the underlying interlayer, with the amounts of rims and viscosity of polymer solutions injected into the other layers, determine the rate of change of speed of movement of the displacement fronts in each of the layers so that their fronts are suited to the production wells at the same time sychosis fact, to provide the desired viscosity of the solution, the type and concentration of polymer is determined on the basis of the data on its rheological and filtration characteristics obtained on core samples extracted from the interlayers.

 

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