RU2433260C1 - Method of sour well intervention in terriogenous reservoir - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: method of sour well intervention in a terriogenous reservoir involves injecting into a productive formation a first processing medium containing, wt %: hydrazine hydrochloride N₂H₄·2HCl 10.8, organic phosphonic acid derivative 0.5, surface-active substance 0.5, corrosion inhibitor 0.5, water the rest. Further, after curing of the processing medium, a buffer liquid containing the surface-active substance in the concentration 0.5-0.8 % is injected into the reaction mixture. It is followed with injection of a second processing medium containing, wt %: hydrazine hydrochloride N₂H₄·2HCl 10.8, ammonium bifluoride NH₄F·HF 4.3, organic phosphonic acid derivative 0.5, surface-active substance 0.5, corrosion inhibitor 0.5, water the rest. Further, after curing of the second processing medium, well completion is performed.

EFFECT: prevented sedimentation in processing of terriogenous reservoirs having carbonate impurities with providing a high degree of filter cake removal ensured by a higher degree of dissolution and dispersion of a clay matter.

2 cl, 3 tbl

Description

The invention relates to the field of oil production, in particular, to the technology of claying out the bottom of the formation, and can be used in the process of developing wells and their operation in order to intensify the flow of oil from the reservoir, composed mainly of terrigenous reservoirs.

A known method of acid treatment of wells (patent No. 2042802, CL EV 43/27). The main disadvantage of this method when claying down the borehole zone is that the solution is able to dissolve only impurities in clay, and, in addition, it disrupts coagulation contacts in clay aggregates without dissolving them.

Closest to the proposed technical solution is a method of treating the bottom of the formation with a solution, which includes 15% HCl, 8% ammonium bifluoride, a surfactant and a corrosion inhibitor (Sidorovsky V.A. Exploration and increase in productivity of wells. M., Nedra, 1978 , 256 pp.) However, in this method, even an insignificant presence of carbonate in the terrigenous reservoir leads to the formation of gel-like calcium fluoride, which significantly reduces the permeability of the bottom-hole zone.

The task of the invention is to improve the dissolution of clay minerals by eliminating the formation of clay-acid treatment of insoluble calcium fluoride. Calcium can be both in the composition of the granular collector, and in clay cobbing formations.

The achievement of the specified technical result is ensured through the use of effective, well-combined with each other ingredients, as well as effective technological methods.

The technical result is achieved by the fact that in the method of acid treatment of wells in a terrigenous reservoir, including pumping the technological solution into the reservoir, holding the technological solution for reaction and subsequent development of the well, the first technological solution is initially pumped into the reservoir containing the following components (wt.%) :

Hydrazine hydrochloric acid N ₂ H ₄ · 2HCl 10.8 organic phosphonic acid derivatives 0.5 surfactant surfactant 0.5 corrosion inhibitor 0.5 water rest,

then, after holding the technological solution for the reaction, a buffer liquid containing surfactant is injected within the concentration range of 0.5-0.8%, then a second technological solution is pumped containing the following components (wt.%):

Hydrazine hydrochloric acid N ₂ H ₄ · 2HCl 10.8 ammonium bifluoride NH ₄ F · HF 4.3 organic phosphonic acid derivatives 0.5 Surfactant 0.5 corrosion inhibitor 0.5 water rest,

and after holding the second technological solution to the reaction, the well is developed.

The width of the distribution zone of the filtration dispersion of the buffer solution should be less than the width of the distribution zone of the first technological solution in the reservoir.

The method is implemented as follows. First, the first technological solution containing the following components (wt.%) Is pumped into the reservoir;

Hydrazine hydrochloric acid N ₂ H ₄ · 2HCl 10.8 organic phosphonic acid derivatives 0.5 Surfactant 0.5 corrosion inhibitor 0.5 water rest.

Hydrazine hydrochloride according to the mechanism of interaction with kolmatiruyuschim education refers to the reagents of multifunctional action. The solvent capacity of the reagent is based both on the acid properties of the aqueous solution, determined by the concentration of H ⁺ hydrogen ions (in the aqueous medium of H ₃ O ⁺ ions), and on the reducing properties of the solution, the reactions of which are accompanied by a change in the oxidation state of the elements that make up the reactants. The process is accompanied by the movement of electrons from the reducing agent to the oxidizing agent, which is part of the clogging formations and dissolves as a result of this process.

As organic derivatives of phosphonic acid, the base base contains nitrilotrimethylphosphonic acid (NTP) or hydroxyethylidene diphosphonic acid (HEDP).

As surfactants, cationic or nonionic surfactants are used, or a mixture thereof, for example, cationic surfactants - Kama-03, nonionic surfactants - neonol AF.

As a corrosion inhibitor use:

SNPCH-6501 (produced according to TU 39-0576570-OP-216-95);

Nuting (produced according to TU 2499-037-53501222-2003);

KI-1 (produced according to TU 6-01-4689387-34-90.

The volume of the first solution is calculated based on the penetration distance into the reservoir, by 0.5 m. The exposure time of the solution to the reaction is 1-2 hours.

Next, a buffer liquid containing surfactant in the range of 0.5-0.8% is pumped. The volume of the buffer solution is calculated by the filtration dispersion.

When the technological solution is pumped into the treatment zone, piston displacement occurs, and this process is accompanied by filtration dispersion processes due to macro- and microinhomogeneity, which inevitably leads to the formation of mutual mixing of the technological solution with formation water and, as a consequence, the secondary formation and deposition of a solid phase from already dissolved components of the clogging formations. In the general case, the mixing zone is located on both sides of the piston displacement boundary. In accordance with the fundamentals of hydrodynamics, a number of formulas have been proposed for determining the width of the filtration dispersion zone L _d , which give similar results. Using the known dependencies and the results of experiments on injection of indicators into sand reservoirs for practical calculations, the following dependence was obtained:

L _d = · (λ · L) ^0.5

where λ is the hydrodispersion parameter, m; L is the piston displacement boundary, i.e. processing zones, m

So, for example, it was experimentally established that for sand reservoirs, the hydrodispersion parameter varies from 0.01 to 0.001, and the coefficient "a" is assumed to be 4.7. The width of the distribution zone of the filtration dispersion of the buffer solution should be less than the width of the distribution zone of the first technological solution in the reservoir. No time for holding the buffer solution is required.

A second process solution is pumped containing the following components:

Hydrazine hydrochloric acid N ₂ H ₄ · 2HCl 10.8 ammonium bifluoride NH ₄ F · HF 4.3 organic phosphonic acid derivatives 0.5 Surfactant 0.5 corrosion inhibitor 0.5 water rest.

The volume of the second clay acid solution must be not less than the volume of the first solution. The exposure time in the reservoir is 1-1.5 hours.

Spend well development.

Example. The specific implementation of the method is illustrated by the materials of pilot works carried out on a number of wells of the Yugansk group of fields. The geological and physical characteristics of the reservoirs and fluids where the reagent treatments of producing wells were given are characterized by the following values (Table 1).

Geological and physical characteristics of formations and fluids of deposits of the Yugansk group

Table 1 No. p / p Indicators Units Values one Average thickness of oil-saturated sandstones m 8.0-8.8 2 Average porosity Shares 0.18-0.24 3 Medium permeability MD 42-130 four Initial oil saturation coefficient Shares 0.51-0.65 5 Formation temperature ° C 90-99 6 Average Depth m 2400-2800 7 Initial reservoir pressure MPa 28.0-31.5 8 Gas factor m ³ / m ³ 56-85 9 Viscosity of oil in reservoir conditions cp 1.16 10 Density of oil in reservoir conditions kg / m ³ 8210-8240

Table 2 presents the results of reagent milling according to the prototype. Table 3 shows the effectiveness of reagent milling according to the claimed method. From the above data it is seen that the average increase in the flow rate of the wells according to the prototype is 49%, and by the present method 322%.

The results shown in tables 2 and 3 show that the proposed method of acid treatment has the following advantages over the prototype.

The effectiveness of the reagent claying wells Yugansk group prototype

table 2 No. Flow rate, t / day Increment p / p Before processing After processing flow rate, t / day one 5,0 7.5 2.5 2 5.3 6.8 1,5 3 6.2 10.5 4.3 four 4.0 9.6 5,6 5 3.9 5.2 1.3 6 4.3 6.3 2.0 7 6.8 8.1 1.3 8 5.8 6.2 0.4

Efficiency of reagent claying of wells of the Yugansk group upon request

Table 3 No. Debit t / day Increment p / p Before processing After processing flow rate, t / day one 6.3 17.1 10.8 2 6.3 18.8 12.5 3 3.2 18.8 15.6 four 4.0 18.8 14.8 5 5.9 22.4 16.5 6 8.3 27.7 19,4 7 5.8 22.8 17.0 8 5.8 20,0 14.2 9 8.3 23.6 15.3 10 3.3 28.5 25,2 eleven 5.2 21.6 16,4

- characterized by high dissolving ability in relation to clay materials, the absence of secondary precipitation even at high reservoir temperatures;

- provides a more significant compared with the prototype increase in the permeability of terrigenous reservoirs in oil, i.e. significantly increases the processing efficiency of the PPP.

Claims (2)

1. The method of acid treatment of wells in a terrigenous reservoir, including the injection of the technological solution into the reservoir, exposure of the technological solution to the reaction and subsequent development of the well, characterized in that the first technological solution is pumped into the reservoir containing the following components, wt.%:
Hydrazine hydrochloric acid N ₂ H ₄ · 2HCl 10.8 organic phosphonic acid derivatives 0.5 surfactant surfactant 0.5 corrosion inhibitor 0.5 water rest,
then, after exposure of the technological solution to the reaction, a buffer liquid containing surfactant is injected within the concentration range of 0.5-0.8%, then a second technological solution is pumped containing the following components, wt.%:
Hydrazine hydrochloric acid N ₂ H ₄ · 2HCl 10.8 ammonium bifluoride NH ₄ F · HF 4.3 organic phosphonic acid derivatives 0.5 Surfactant 0.5 corrosion inhibitor 0.5 water rest,
and after holding the second technological solution to the reaction, the well is developed. 2. The method according to claim 1, characterized in that the width of the distribution zone of the filtration dispersion of the buffer solution is less than the width of the distribution zone of the first technological solution in the reservoir.