RU2595019C1 - Process fluid for well killing based on alcohols - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil and gas industry and can be used during killing of oil-producing wells before overhaul, development, perforation. Process fluid for well killing based on alcohols containing oxal T-92 floatation agent, according to the invention additionally contains polyfluorinated trihydrooktafluoroamyl alcohol-telomere in the following proportions, wt%: polyfluorinated trihydrooktafluoroamyl alcohol-telomere 2-75, oxal T-92 floatation agent 25-98.

EFFECT: wider range of the fluid density change, preservation of filtration-capacitance parameters of productive reservoirs due to inhibition of clay minerals hydration.

1 cl, 2 tbl, 1 ex

Description

The invention relates to the oil and gas industry and can be used for killing oil wells before major repairs, development, perforation.

At present, oil, water, produced water, and aqueous and hydrocarbon-based drilling fluids are used as well killing fluids. The latter are most effective, however, they are relatively high cost, dangerous in terms of environmental pollution, fire, etc.

Known liquid for killing wells containing polyglycols, denatured alcohol and water in the following ratio of components, vol.%:

Polyglycols 40-45 Denatured alcohol 30-35 Water rest

(RF patent No. 2187532 from 08.20.2002).

A disadvantage of the known liquid is the presence in the composition of polyglycols, which when interacting with carbonate rocks form water-insoluble salts. The killing fluid is prone to foaming, causing swelling and dispersion of clay minerals. All this leads to a decrease in the permeability of the bottom-hole zone of wells and their productivity coefficient.

The closest composition of the same purpose to the claimed invention according to the totality of features is a well killing fluid, including polyglycols, aliphatic alcohol, flotation reagent - oxal and water in the following ratio of components, vol.%:

polyglycols 5-35 flotoreagent oxal 45-65 aliphatic alcohol 15-20 water rest

As an aliphatic alcohol, well killing liquid contains ethyl, or isopropyl, or butyl alcohol (RF patent No. 2260112 of 09/10/2005).

Signs of the prototype, coinciding with the features of the claimed invention is flotoreagent-oxal T-92.

The disadvantages of the known fluid adopted for the prototype are the low density range of the fluid and the presence of water in the composition, which can lead to swelling of clay minerals present in the reservoir.

The objective of the invention is to expand the range of changes in the density of the liquid, preserving the filtration-capacitive parameters of productive reservoirs by inhibiting the hydration of clay minerals.

The problem was solved due to the fact that the well-known technological fluid for killing wells based on alcohols containing flotation reagent Oxal T-92 additionally contains polyfluorinated trihydrooctafluoroamyl alcohol telomere H (CF2CF2) 2CH2OH) in the following ratio of ingredients, wt. %:

Polyfluorinated trihydrooctafluoroamyl alcohol telomere 2-75 flotation reagent oxal T-92 25-98

Distinctive features of the proposed solution from the solution of the prototype is the introduction of polyfluorinated trihydrooctafluoroamyl alcohol-telomere; different quantitative ratio of the used ingredients wt. %: polyfluorinated trihydrooctafluoroamyl alcohol telomere - 2-75; flotation reagent oxal T-92 - 25-98.

The developed composition of the killing liquid based on heavy alcohols when interacting with clay minerals contained in the reservoir rock does not cause their swelling. Due to this, the problem of preserving the filtration-capacitive properties of productive formations is solved.

The proposed liquid is not prone to foaming, hardy. The required fluid density is achieved by mixing the components in an appropriate amount.

To obtain the proposed fluid for killing wells in laboratory conditions, the following substances were used:

- polyfluorinated trihydrooctafluoroamyl alcohol telomere (chemical formula: H (CF2CF2) 2CH2OH) according to TU 6-09-4830-80, is a colorless heavy liquid.

- flotation reagent oxal T-92 according to TU 2452-029-05766801-94. The product is a yellow to brown liquid that does not exfoliate, has a slight aromatic odor, contains more than 50% dioxane esters and alcohols, and also close to 50% of a mixture of 1, 2 and 3 atomic alcohols.

The possibility of carrying out the claimed invention is confirmed by the following examples.

Example 1

To obtain the claimed fluid for killing wells in laboratory conditions, 22 g (98%) of flotation reagent of oxal T-92 with a density of ρ = 1.09 g / cm ³ were taken, 0.45 g (2%) of polyfluorinated trihydrooctafluoroamyl alcohol telomer H ( CF2CF2) 2CH2OH) with a density ρ = 1.65 g / cm ³ was mixed. The resulting kill fluid has a density ρ = 1.10 g / cm ³ .

Example 2

To 11 g (48%) of the flotation reagent of oxal T-92 with a density of ρ = 1.09 g / cm ³ , 12 g (52%) of polyfluorinated trihydrooctafluoramyl alcohol telomere H (CF2CF2) 2CH2OH) with a density of ρ = 1.65 g was added / cm ³ was mixed. The resulting kill fluid has a density ρ = 1.30 g / cm ³ .

Example 3

To 11 g (25%) of the flotation reagent of oxal T-92 with a density of ρ = 1.09 g / cm ³ , 33 g (75%) of polyfluorinated trihydrooctafluoramyl alcohol telomere H (CF2CF2) 2CH2OH) with a density of ρ = 1.65 g was added / cm ³ was mixed. The resulting kill fluid has a density ρ = 1.51 g / cm ³ .

In the process of testing the obtained fluid, we determined the values of the properties of the obtained fluid — density, conditional viscosity, pH, mineralization, restoration of the filtration-capacitive properties of the reservoir. Measurement of the main technological parameters of the obtained killing fluid was carried out on standard instruments.

Data on the properties of known and proposed liquids are given in table 1.

As can be seen from the table, the inventive fluid for killing wells has a wide range of density changes (1100 ... 1510 kg / m ³ ).

The developed composition of the killing liquid based on heavy alcohols will allow avoiding the swelling of clay minerals. The kill fluid does not have a water component and does not mix with water-based solutions; its use does not lead to accelerated corrosion of casing strings and downhole equipment; it can be reused. In addition, the inventive liquid has a wide range of application temperature (-37 ... + 85 ° C).

The claimed killing fluid was tested in laboratory conditions to establish its effect on the restoration of the permeability of core samples from productive formations in the Perm Territory. An estimate of the restoration of initial permeability was studied on samples of rocks from the Bobrikovsky deposit of the Unvinsky and Siberian deposits. For each sample, porosity, kerosene permeability, permeability after exposure to the sample with a kill fluid, and permeability recovery coefficient were determined. The test results are shown in table 2.

The average permeability recovery coefficient for all samples was 92%.

As can be seen from the table, the test results indicate the high efficiency of the developed process fluid. Using the proposed killing fluid in fields with hard-to-recover oil reserves will allow us to maintain the reservoir properties of the productive formations, improve the quality of casing strings, reduce the likelihood of cement stone destruction by using gentle methods of re-opening the productive formations and improve the quality and effectiveness of these measures.

Claims (1)

.
Technological liquid for killing wells based on alcohols containing flotation reagent oxal T-92, characterized in that it additionally contains polyfluorinated trihydrooctafluoroamyl alcohol telomere in the following ratio of ingredients, wt. %:
Polyfluorinated trihydrooctafluoroamyl alcohol telomere 2-75 flotation reagent oxal T-92 25-98