RU2307241C1 - Method for oil field development - Google Patents

Abstract

FIELD: oil production, particularly to develop watered non-uniform oil reservoir with flooding thereof from porous fissured reservoirs having non-uniform compositions and formed by terrigenous and carbonate deposits.

SUBSTANCE: method involves performing simultaneous injection of reagents, namely aqueous biological surfactant solution and filler, in reservoir via injection well; forcing the reagents in reservoir with water and performing technological time delay for 24 hours. Reagent mass ratio is 90:10. The filler is wood flour.

EFFECT: increased efficiency due to possibility of active weakly drainable reservoir zones development, which provides oil recovery increase.

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Description

The invention relates to the oil industry, and in particular to methods for developing an irrigated heterogeneous oil reservoir by flooding of terrigenous and carbonate deposits that are heterogeneous in the geological structure of fractured-pore formations.

A known method in which for the displacement of oil using bio-surfactants and hydrocarbon solvent (patent No. 2041345, ЕВВ 43/22).

This method is not effective enough in fractured-pore reservoirs due to the high consumption of reagents for creating a water-insulating screen and its rapid erosion by pumped water.

A known method of isolating absorption zones in an injection well, including pumping through an injection well an aqueous suspension of wood flour 0.15-0.35% concentration during the swelling time of wood flour in water under reservoir conditions (RF patent No. 2089716, MKI E21B 38/138, 1997).

The disadvantage of this method is the low efficiency due to the impossibility of completely blocking water-washed cracks and super-permeable zones of the formation and due to the focus only on the isolation of water-washed zones of the formation.

The closest analogue is a method of developing an oil field, including the injection of an aqueous solution of a biological surfactant bio-surfactant KSHAS-M and filler bentonite clay (RF patent No. 2154160, ЕВВ 43/22, 1999).

However, this technical solution is not effective enough in fractured-pore-cavernous reservoirs due to erosion of the resulting insulating material by injected water.

The technical result of the invention is to increase the efficiency of a method for developing an irrigated heterogeneous oil reservoir, which allows, through overlapping fractures and high-permeability zones of the reservoir, to include in the active development low-draining low-permeability zones of the reservoir, which contributes to an increase in the extraction of oil reserves from the reservoir.

In the method of developing an oil field, including the joint injection of reagents through an injection well, an aqueous solution of the biological surfactant bio-surfactant KSHAS-M and filler, and technological exposure, the reactants are injected in a mass ratio of 90:10, respectively; wood flour and reagents are used as filler pressed into the reservoir with fresh water, and technological exposure is carried out within 24 hours.

KSHAS-M bio-surfactant according to TU 9296-015-00479770-2000 is a natural aqueous bio-surfactant composition of glycolipid nature produced by the microorganism culture Pseudomonas aeruginosa S-7. KSHAS-M bio-surfactant solutions have the ability to reduce the surface tension of water to 30 mN / m, as well as high emulsifying activity (liquid paraffins, oil, oils) E ₂₄ to 60-80% (E ₂₄ - emulsion stability for 24 hours). Their main advantage is biodegradability or the ability to completely decompose under natural reservoir conditions, i.e. bio-surfactant technologies are environmentally friendly.

Wood flour - a product of dry wood chopping according to GOST 16381-87, is a polydisperse material of a fibrous structure.

When a composition of an aqueous solution of a biological surfactant bio-surfactant KSHAS-M and wood flour is injected into the formation through injection wells, it enters into cracks and, moving along it, particles of wood flour form friable flocculent aggregates (flocs) due to the fibrous structure of wood flour particles. As a result of this, due to the swelling of wood flour particles and an increase in volume, an insulating system that is more resistant to erosion is formed, which provides gradual overlapping of cracks and highly permeable zones of the formation. Technological exposure (pause) should be at least 16 hours, preferably 24 hours.

The effectiveness of the proposed method for the development of an irrigated heterogeneous oil reservoir was determined by the residual resistance factor and an increase in the oil recovery coefficient. For this, a heterogeneous reservoir model was used. In physical modeling, the model consists of two hydrodynamically unbound interlayers, which are metal columns filled with a porous medium. Interlayers have a common entrance for pumping liquids. The length of the interlayers is 0.6 m, diameter 3.0 · 10 ^-2 m. Ground quartz sand served as a porous medium.

The experimental technique was as follows.

To create bound water in a porous medium and initial oil saturation, the models of the layer after preliminary evacuation were saturated with formation water followed by its displacement with oil. The amount of bound water and oil in a porous medium was determined by the volume-weight method. The experiments were carried out in a constant flow rate of injected fluid (~ 20 cm ³ / h) at a temperature of 25 ° C.

Then, primary flooding was carried out to a certain oil saturation and stabilization of the filtration characteristics, which occurs after reaching 100% water cut in the production of a highly permeable layer. The degree of water cut of the product extracted from the reservoir model as a whole was achieved by selecting the ratio of the permeability of the layers. After injection of the reagents, the waterflooding process resumed. The results of the study of the process of oil displacement using the method are shown in the table.

Example 1 (prototype).

0.3 pore volumes (bp) of a mixture of an aqueous solution of a biological surfactant bio-surfactant KSHAS-M, a hydrocarbon solvent and bentonite clay are pumped into the reservoir model at a ratio of 1: 1: 0.2. Technological exposure 48 hours. Then the displacement is pumped water. The oil recovery factor is 10.5%. The residual resistance factor is 18.

Example 2 (the proposed method).

In the reservoir model, they are pumped simultaneously in a mixture of bio-surfactant KSHAS-M and wood flour (90:10 ratio) - 0.2 bp The reagents are pushed with fresh water - 0.05 bp Stop filtering for technological exposure for 24 hours. Then resume the experience. The residual resistance factor is 35.1. Oil recovery growth - 17.4%.

An example of a specific implementation of the method in the field.

The field is characterized by layer-by-layer heterogeneity, high injectivity of injection wells (more than 100 m ³ / day).

Water cut of extracted products - 90%. The average permeability is 0.13 μm ² . Porosity - 0.2-0.25. Formation oil has a viscosity of 1.8 MPa · s. Produced water of chloride-calcium type with low salinity (18.6 kg / m ³ ). The reservoir was opened by one injection and one producing well. The density of the well mesh is 25 ha / well.

To implement the method, the injection of wastewater into the injection well is stopped. Injected an aqueous solution of bio-surfactant KSHAS-M and wood flour (with a ratio of components in wt.% - 90:10) in an amount of 15 m ³ . Reagents push 15 m of fresh water. The well is stopped for 24 hours "for reaction" (technological exposure). After treatment, the reservoir is further exploited by conventional waterflooding.

The working volumes of injected reagents are determined depending on the specific injectivity of the wells and the thickness of the formation.

Processing of the injection well is carried out by the installation of TsA-320 M.

Three months after well treatment, a decrease in water cut in well production from 92.5% to 80% was observed, and the specific technological effect was 70-80 tons per 1 ton of reagents.

The proposed method is highly effective for increasing oil recovery at a late stage of development, where it is necessary to align injection profiles of injection wells, isolating water-washed zones, limiting water inflow, followed by intensification of oil production from undrained zones of the formation.

Claims (1)

A method of developing an oil field, including the joint injection of reagents through an injection well - an aqueous solution of a biological surfactant bio-surfactant KSHAS-M and a filler and technological exposure, characterized in that the reagents are injected in a mass ratio of 90:10, respectively, using wood as a filler flour, reagents are pressed into the reservoir with fresh water, and technological exposure is carried out for 24 hours