RU2490444C1 - Method for near well-bore treatment with acid - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method for near well-bore treatment with acid involves at the first stage pumping into the well of 10-15% aqueous solution of hydrogen chloride in a volume calculated on the basis of 0.25-0.5 m³ per 1 running metre of penetrated stratum depth; at the second stage - pumping of 10-15% aqueous solution of hydrogen chloride with a retarder of the acid reaction with rock in the volume of 2-5% of acid solution volume in total volume of pumping calculated on the basis of 1-1.5 m³ per 1 running metre of penetrated stratum depth at initial pressure equal to the final pressure value during pumping at the previous stage; overflushing by oil in volume of 5-15 m³ at initial pressure equal to the final pressure value during pumping at the previous stage; soaking during 16-48 hours and input of the well into operation.

EFFECT: improvement in efficiency of near-wellbore treatment.

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Description

The invention relates to the oil industry and may find application in the acid treatment of the near-wellbore zone.

A known method of acid treatment of the bottom-hole zone of an oil reservoir, which includes the injection of a diverter - a hydrocarbon gel prepared using the Himeko-N gelling agent, the Himeko-N activator and diesel fuel and subsequent treatment of at least one low-permeability zone of the formation with hydrochloric acid with a concentration of from 12 to 24%, while in repeated processing operations, hydrochloric acid is used with a decreasing concentration and a decrease in its volume (RF Patent No. 2456444, publ. 20.07.2012).

Closest to the proposed invention in technical essence is a method of extracting oil by injecting into the formation an acid composition containing acid and a composition containing a surfactant and a liquid hydrocarbon, the acid composition additionally contains a moderator of the reaction with the formation rock - or Zeolite, or crumb of synthetic zeolites, or syenite alumina alkali concentrate, or industrial lignosulfonates, or carboxymethyl cellulose - KMTS, or Politsell KMTS KMTS-9N, KMTs-9S, or alumochlori or aluminum hydroxyl chloride, in the following ratio of components, wt.%: acid 97.5-99.9, said moderator 0.1-2.5, the acid composition is injected before or simultaneously with the composition containing surfactant and liquid hydrocarbon when they are the ratio of wt.%: surfactant 5-16, liquid hydrocarbon 84-95, with a ratio of its volume to the volume of the acid composition from 2 to 4. Moreover, the components are pumped simultaneously into production and injection wells (RF Patent No. 2295635, published. 03/20/2007 - prototype).

A common disadvantage of the known methods is the low processing efficiency, expressed in a slight increase in well productivity after treatment.

In the proposed invention solves the problem of increasing processing efficiency.

The problem is solved by the method of acid treatment of the near-wellbore zone, which includes, at the first stage, the injection of a 10-15% aqueous hydrochloric acid solution into the well at the rate of 0.25-0.5 m ³ per 1 m of perforated formation thickness, at the second stage, the injection of 10-15 % hydrochloric acid solution with a retarder in the amount of 2-5% of the volume of the acid solution at the rate of 1.0-1.5 m ³ per 1 m of perforated reservoir power at an initial pressure equal to the final injection pressure in the previous stage, oil selling in a volume of 5-15 m ³ with an initial pressure equal to the final d to the injection at the previous stage, technological exposure for 16-48 hours and putting the well into operation.

SUMMARY OF THE INVENTION

Carbonate formations are characterized by multidirectional fracturing, heterogeneity and low oil recovery.

In the case of high viscosity of the produced oil after drainage from the reservoir adjacent directly to the well perforation zone, a sharp drop in oil production is observed due to non-Newtonian properties of the formation fluid. Existing technologies are not effective enough in these conditions. The proposed complex treatment of the carbonate reservoir is aimed at involving low-permeability and isolated zones of the formation in the development. The consequence of this is an increase in well production and, ultimately, oil recovery.

During processing, they increase the permeability of the low-permeability part of the formation, improve the reservoir properties of the formation through the use of hydrochloric acid, increase the coverage of acid exposure to the formation by adding a moderator of the reaction of the acid with the rock.

An important point is the continuity of all work, i.e. component injection at a subsequent stage of work with an initial pressure equal to the final pressure at the previous stage.

An essential feature of the proposed invention is the ratio of injection volumes of a hydrochloric acid solution and a hydrochloric acid solution with a moderator as (0.25-0.5) :( 1.0-1.5). As practice has shown, it is precisely this ratio that makes it possible to achieve the greatest increase in well production as a result of processing.

The ratio of components in solutions and the volumes of injected components are determined from practice as the most optimal for solving the task. Exceeding the declared limits leads to a decrease in processing efficiency.

As a moderator of the reaction of hydrochloric acid with the rock, use is made of THP-1, manufactured according to TU 2481-002-72650092-2009, or SNPCH-8903 A (TU 2458-314-05765670-2006 with amendment No. 1). Can be used classic moderators specified in the description of the prototype.

Case Studies

Example 1. Develop the Yeryklinskoye field Bashkir stage. The collector is carbonate. The average well flow rate is 1.6 tons / day. The average water cut is 11.6%. The reservoir has a porosity of 13.2%, permeability of 81.3 μm ² _* 10 ^-3 , oil saturation of 82.4%, the initial reservoir pressure of 9 MPa, the depth of the bottom of the reservoir 1041.5 m, reservoir temperature 23 ° C, the viscosity of the oil in the reservoir 292.5 MPa * s, oil density 937 kg / m ³ .

At the first stage, a 10% aqueous hydrochloric acid solution is pumped into a reservoir with a carbonate reservoir through a stopped oil producing well No. 1 in a volume of 3.5 m ³ (0.25 m ³ per 1 m perforated capacity) at an initial pressure of 0.3 MPa and a final pressure of 0.3 MPa, at the second stage, 14 m ³ (1 m ³ per 1 p.m. of perforated reservoir thickness) is pumped with a 10% hydrochloric acid solution with a reaction inhibitor TXP-1 in a volume of 2% of the volume of the acid solution at an initial pressure of 0.3 MPa and a final pressure of 0.5 MPa, they sell oil in a volume of 5 m ³ at an initial pressure of 0.5 MPa and a final pressure of 1 MPa, carry out technological exposure for 16 hours and put the well into operation.

As a result, the flow rate of the well increased from 1.8 to 4.5 m ³ / day.

Example 2. Perform as example 1.

At the first stage, a 12% aqueous hydrochloric acid solution is pumped into a reservoir with a carbonate reservoir through a stopped oil producing well No. 2 in a volume of 10 m ³ (0.4 m ³ per linear meter of perforated reservoir power) at an initial pressure of 0.25 MPa and the final pressure of 0.25 MPa, at the second stage, 30 m ³ (1.2 m ³ per linear meter of perforated reservoir power) is pumped with 12% hydrochloric acid solution with a reaction inhibitor SNPCH-8903 A in an amount of 3.5% by volume acid solution at an initial pressure of 0.25 MPa and a final pressure of 0.5 MPa; eftyu in a volume of 10 m ³ at an initial pressure of 0.5 MPa and a final pressure of 1.1 MPa, exposure process is performed for 24 hours and injected into the wellbore operation.

As a result, the flow rate of the well increased from 1.8 to 4.8 m ³ / day.

Example 3. Perform as example 1.

At the first stage, a 15% aqueous hydrochloric acid solution is pumped into a reservoir with a carbonate reservoir through a stopped oil producing well No. 3 in a volume of 12 m ³ (0.5 m ³ per linear meter of perforated reservoir power) at an initial pressure of 0.2 MPa and the final pressure of 0.2 MPa, at the second stage, 36 m ³ (1.5 m ³ per linear meter of perforated formation capacity) is pumped with a 15% hydrochloric acid solution with a reaction retardant TXP-1 in an amount of 5% of the volume of the acid solution at the initial pressure of 0.2 MPa and the final pressure of 1.6 MPa, produce a sale of oil volume of 15 m ³ at an initial pressure of 1.6 MPa and a final pressure of 1.9 MPa, exposure process is performed for 48 hours and injected into the wellbore operation.

As a result, the flow rate of the well increased from 1.5 to 4.4 m ³ / day.

The application of the proposed method will improve the processing efficiency of the near-wellbore zone.

Claims (1)

The method of acid treatment of the near-wellbore zone, which includes, at the first stage, pumping a 10-15% aqueous solution of hydrochloric acid into the well in a volume of 0.25-0.5 m ³ per 1 linear m perforated formation thickness, at the second stage, pumping 10- 15% aqueous hydrochloric acid solution with an inhibitor of the reaction of acid with rock in the amount of 2-5% of the volume of the acid solution in the injection volume at the rate of 1-1.5 m ³ per 1 running m of perforated formation thickness at an initial pressure equal to the final pressure injection at the previous stage, oil sales in volume 5-15 m ³ at an initial pressure equal to the final injection pressure at the previous stage, technological exposure for 16-48 hours and putting the well into operation.