SU1694858A1 - Method of selective isolation intervals in well with high permeability - Google Patents

Abstract

The invention relates to an oil producing industry and is intended for the selective isolation of highly permeable intervals in heterogeneous formations, mainly in water injection wells. The purpose of the invention is to increase the efficiency of the method by increasing the selectivity of blocking highly permeable intervals while reducing the consumption of reagents. For this, an aqueous solution of the polymer and hydrochloric acid is sequentially pumped into the formation. Moreover, polymethyl methacrylate modified with monoethanolamine in the aqueous phase is used as the polymer. Solutions of the polymer and hydrochloric acid are used with equal concentrations from 0.1 to 0.4 wt.% And in equal volumes. Hydrochloric acid has a coagulating effect on the polymer to form a blocking precipitate. The use of low concentrated polymer solutions avoids a decrease in the permeability of unproductive intervals. The method is implemented using standard techniques and is recommended in formations with permeability heterogeneity of 8–10 reservoirs under conditions of pore and porous-fractured reservoirs. 1 tab. ABOUT

Description

The invention relates to the oil industry, in particular, to methods for selectively isolating highly permeable intervals in heterogeneous formations, mainly in water injection wells.

The purpose of the invention is to increase the efficiency of the method by increasing the selectivity of blocking highly permeable intervals when

while reducing the consumption of reagents.

The purpose of the invention is achieved by sequential injection of aqueous solutions of the polymer and hydrochloric acid, polymethyl methacrylate modified with monoethanolamine in the aqueous phase being used as the polymer, and solutions of the polymer and hydrochloric acid are used with equal concentrations from 0.1 to 0.4 wt.% And in equal amounts.

wore

Polymethyl methacrylate modified with monoethanolamine in the aqueous phase,

(Deman)) is a water soluble / polymer of formula;

SI,

produced by the domestic industry and is used to increase oil recovery, a positive effect is achieved due to the coagulating effect of hydrochloric acid on the polymer and the formation of particles capable of selectively isolating the highly permeable part of the formation without clogging up the low-permeability interlayers.

To experimentally verify the efficiency of the method under comparable conditions, a series of laboratory experiments on a water-saturated two-plate model was carried out. The permeability of the low permeable formation is 0.12 - 0.16 µm2, the high permeability 1.07 - 1.36 µm2. The dimensions of the models are - 500 mm (length) and 30 mm (diameter). The porous medium is represented by quartz sand of various fractional composition, due to which permeability heterogeneity was achieved. At the first stage of the experiments, water was supplied to the model and the distribution of the filtration flow (R) was established, according to the permeability of porous media through water. In the second stage, the chemical solutions were filtered. The total volume of reagent solutions (polymer and acid) does not exceed 0.3 of the total pore volume of the formation. Evaluation of the effectiveness of the effect of reducing the permeability of the reagent is produced to the dimensionless distribution parameter

R he

where QB is the fluid flow rate in the highly permeable layer;

It is the flow rate of a fluid through a low-permeable plate.

The results of the experiments are given in the table.

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As can be seen from the above data, the application of the method allows to significantly increase the flow of water into the low permeable formation. Comparison of the obtained data shows that the effectiveness of the proposed method exceeds the efficiency of the known method in the concentration range of 0.1 - 0.4%. At the same time, the consumption of reagents — polymer and acid — decreases by a factor of 10 with equal radii of action.

Example. The implementation of the well treatment.

A well conducting a set of geophysical and hydrodynamic studies, identifies highly permeable intervals and their relative pickup. The required degree of leveling of the inhomogeneity of filtration in the formation is justified and the concentration of reagents is selected. With the help of a pumping unit of type CA — 320 m, the prepared polymer solution and hydrochloric acid solution are sequentially pumped into the well in the same volume and with the same concentration. After that, the reagents are forced into the reservoir, which, when mixed, form a blocking tampon at high-permeable intervals.

The method is recommended for use in formations with permeable heterogeneity of interlayers 8-10 in pore and pore fractured conditions.

Claims (1)

Claims of the Invention A method for selectively isolating highly permeable intervals in a well, including sequential injection of aqueous solutions of polymer and hydrochloric acid, in order Polymethyl methacrylate modified with monoethanolamine in the aqueous phase is used as the polymer, and  In experiments 9-10, solutions of hypane and hydrochloric acid of equal concentrations were used; in experiment 11, a solution of hydrochloric acid of 10% concentration was used. polymer and hydrochloric acid solutions - solutions with equal concentrations from 0.1 to 0.4 wt.% and in equal volumes.