SU1629501A1 - Well killing method - Google Patents

Abstract

The invention relates to the killing of wells during capital and underground repairs, as well as during the commissioning of wells after drilling. The goal is to increase the efficiency of the subsequent development of the well by maintaining the reservoir-filtration characteristics of the reservoir. The method includes the sequential injection into the bottomhole zone of an aqueous solution of non-ionic surfactants with their concentration in the solution exceeding the critical concentration of micelle formation by the amount of sorption by their formation rock, blocking fluid and kill fluid. The phase-inversion temperature of the surfactant solution in a system with a formation fluid is not more than 10 ° C below the temperature of the bottom zone, while an invert emulsion with zero filtration and a conditional viscosity more than 400 s is used as a blocking fluid, and the jamming fluid has a density of below the density of the blocking fluid. Oxyethylated mono- and diisononylphenols or their mixtures are used as non-inogenic surfactants. The method allows to commission a well with a steady increase of 20–30% in production rate with a reduction in the development time of 16 times 1 Cp f-crystals. (Ls

Description

The invention relates to the oil and gas industry, in particular to killing wells during capital and underground repairs, as well as during the commissioning of wells after drilling.

The purpose of the invention is to increase the efficiency of the subsequent development of the well by maintaining the reservoir-filtration characteristics of the reservoir.

The use of solutions of non-ionic surfactants (SAS) with the specified characteristics provides low interfacial tension at the interface with the formation fluid and thus prevents the formation of coarse-dispersed water phase globules that clog the low-permeable part of the collector. In the area of phase inversion, the colloidal The structure of the surfactant solution system is formation fluid. The resulting invert micelle solution becomes related both to reservoir hydrocarbons and to the blocking fluid. At - Tp 10 10 ° С, the sorption of surfactants on a porous medium increases dramatically, which leads to a drop in the effective concentration of surfactants in the solution, an exponential jump in interfacial tension. As a result of the hydrophobization of the reservoir, its phase permeability with respect to hydrocarbon products

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which makes it difficult to master wells after repairs.

When the conditional viscosity of the blocking fluid is below 400 s, the structural-mechanical and blocking properties are sharply reduced, especially in highly permeable (more than 1 D) reservoirs, which subsequently leads to absorption and difficulty in developing wells.

The method is carried out as follows.

When a well is put into operation after drilling or when carrying out repair operations, a solution of non-ionic surfactants selected from the group of hydroxyethyl mono and / or diisononylphenols is pumped into the perforation interval of the productive formation through tubing. phases and interfacial on the platform so that the phase-inversion temperature of this solution in the system with a plug-in fluid is no more than 10 ° C below the bottom hole temperature.

The surfactant solution is prepared with a content of 1-0% non-ionic surfactants and is injected with a volume of 0.1-1.0 m3 per 1 m of the perforated formation thickness. With a high permeability of the reservoir (more than 1 D), a hydrophobic-emulsion solution is then injected, for example, on the basis of emultal, penazolin, ukramin, gas chemistry, dehydrated polyamides ES-2, so that its density is higher than that of the killing fluid. less than 30 kg / m, then balance the reservoir pressure with a killing fluid - with an aqueous solution of inorganic salts NaCI, CaCta, MgCte, KCI, KBr2, and others or their mixtures.

Having balanced the reservoir pressure, they start repair work. After the repair is completed, a well is pumped from the well by successively replacing the injecting fluid in the well with a fluid or gas-condensate mixture of lower density, lowering the column or lowering the fluid level in the well.

Example 1: The method was carried out in a well characterized by the following parameters:

The reservoir thickness is effective, m 94 Perforation interval, m1166-1185

Perforated power, m19

Plastova temperature, ° С32

Optimum flow rate, thousand m / day

610

As a buffer liquid, a 1% solution of Neonol AFE-12 was used according to the proposed method of extinguishing, which is carried to the group of oxazylated

monozonylphenols with a degree of oxyethylation of 12, in a 15% solution of CaCte. The interfacial tension of this solution at the interface with the stabilized gas condensate is 8-102 mN / m, and the phase-inversion region in the system with formation fluid is 30 ° С, i.e. 2 ° C below the temperature of the well bottom zone.

Invert emulsion (IZ) with a density of 1240 kg / m3, which has zero filtration and conditional viscosity for more than 30 minutes, was used as a blocking fluid. IE was prepared by dissolving in a cementing unit CA-320 105 l of zmultala

in 345 l of gas condensate with the gradual introduction into it of a suspension of chemically precipitated chalk (107 kg) in 225 m3 of CaCl2 solution with a density of 1150 kg / m3 and subsequent mixing to itself (about 2 hours)

through a dispersant to obtain an inverse emulsion with the specified parameters.

According to the proposed method, 14 m3 of a 20% CaCte solution (density 1177 kg / m3), 3

m buffer and 3 m blocking fluid. With the help of the TsA-320 unit, buffer fluid was sold to the reservoir and at the same time the wellbore was filled with a 20% calcium chloride solution.

The well was under repair for 32 days. During this period, absorption of the solution was not observed.

After well repair, it was mastered in the usual way - by replacing the plugging fluid with gas condensate and deblocking the formation with a solution of 20% hydrochloric acid in acetone in a volume ratio of 1: 1.

The well was put into operation after 0.125 days after the repair with a flow rate exceeding the pre-repair one by 130 thousand m3 / day.

PRI mme R 2. Well has the following options:

Power effective, formations m 95.5 Perforation interval, m 1149-1173 Perforated formation power, m24

Plastova temperature, ° С32

Optimum flow rate, thousand m / day 550

A 7% Neonol AFD-12 solution in a 15% CaCIa solution was used as a buffer liquid, and an IE density of 1250 5 kg / m with zero filtration and a viscosity of 1080 s was used as a blocking liquid. 4 m of IE was prepared analogously to example 1. For the preparation, 80 l of emulsalum, 720 l of gas condensate, 112 kg of chalk and 2.8 m of mineralized water with a density of 1400 kg / m3 were used.

The killing and development of the well were carried out analogously to example 1.

After repair (56 days) over the course of 0.125 days, the well entered a stable mode with a flow rate of 660 thousand m3 / day.

PRI me R 3. The well is characterized by an open perforation interval with a capacity of 45 m, a reservoir temperature of 34 ° C and a flow rate of 600 thousand m3 / day.

To suppress it, 6 m3 of buffer liquid (10% aqueous solution of Neonol AFD-12 in a 15% solution of CaCte) and 6 m3 of an IE blocking solution with a density of 1180 kg / m3, a conditional viscosity of 420 s and zero filtration were used.

For the preparation of 6 m, IE with the following parameters were used: 60 l of emulsalum, 1.44 m3 of gas condensate, 224 kg of chalk and 3.9 m of mineralized water with a density of 1110 kg / m.

The killing and development of the well were carried out analogously to example 1.

After repair, which lasted for 93 days, within 0.125 days of the well entered the stable mode with a flow rate of 800 thousand m3 / day.

The advantages of the proposed method as compared with the base case are to reduce the time required to complete the wells by 16 times, to increase the reliability of plugging (there was no absorption during the pilot tests at high-permeable gas wells (more than 0.8 D)).

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The reservoir filtration characteristics of the reservoir using the proposed method are not only preserved, but the well productivity in the post-repair period is increased by 20-30%.

Claims (2)

1. A well-killing method, including sequential injection of water into the well zone, blocking fluid and killing fluid with a density lower than that of the blocking fluid, which, in order to increase the efficiency of the subsequent development of the well characteristics of the reservoir, an additional non-ionic surfactant is introduced into the water in an amount that provides an excess of the critical concentration of micelle formation by the amount of sorption of their reservoir porosity In this case, the phase-inversion temperature of the solution in the system with formation fluid is more than 10 ° С lower than the temperature of the bottomhole zone, and an invert emulsion with zero filtration and conditional viscosity more than 400 s is used as a blocking fluid. 2. Method as claimed in claim 1, wherein oxoxylated mono- and diisononylphenols or mixtures thereof are used as nonionic surfactants.