SU1742467A1 - Hydrophobic emulsion for reservoir treatment - Google Patents

Abstract

The essence of the invention: the emulsion contains, in wt.%: 20-30 dehydrated degassed oil with a density of 720-900 kg / m3, 0.01-1.0 ferrochrome lignosulfonate, the rest is fresh water or formation water or 22% hydrochloric acid. Oil viscosity should not exceed 30 MPa s at 20 ° C. It may contain, in wt.%: Up to 6 paraffins and up to 35 asphalt-resinous substances. The emulsion is prepared by dissolving the ferrochrome lignosulphonate in oil, after which, with vigorous stirring, water or hydrochloric acid are added in 3-4 portions into the solution and mixed again for 30 minutes. 2 tab.

Description

The invention relates to the oil and gas industry, in particular to process fluids, which are hydrophobic emulsions, used for hydraulic fracturing of oil and gas reservoirs, processing carbonate reservoirs, killing and preserving wells, and perforating works in wells, as well as for limiting water inflows .

Emulsions can be of two types: oil is dispersed in water (direct emulsion is hydrophilic) or vice versa, water is dispersed in oil (reverse type emulsion is hydrophobic),

The proposed emulsion refers to hydrophobic emulsions in which the oil is an external phase, and the internal phase can be a formation water or a solution of salts or acids.

Hydrophobic emulsion is most effective when processing formations. Firstly, no direct contact of the acid with the formation rock occurs, and secondly, the acid inside the emulsion can be pumped into the formation without losing its activity, and there under conditions of prolonged stay in the capillary channels - space will produce useful work with increasing permeability of the rock.

Hydrophilic refers to water-based working fluids, since the external environment in this type of emulsion is water and therefore does not have the properties described above.

The known hydrophobic oil acid emulsion for hydraulic fracturing, consisting of a hydrocarbon fluid, hydrochloric acid, and an emulsifier for non-iniogenic surfactant-neonol P12-16-3. The emulsion of this composition has a viscosity of 70-150 mPas

(L

WITH

Vj

Ј

Yu

4 o 4

c, which is destroyed only at temperatures above 120 ° C.

A hydrophobic emulsion is known, containing the following components,%:

Salt oil17-25

Water 74,8-82,6

Alkylolamide 0.2-0.4

This emulsion, depending on the amount of emulsifier and the ratio of hydrophobic and hydrophilic phases, has a viscosity of 30-200 spz and has insufficient thermostability. The closest to the technical essence and the achieved effect to the claimed is a hydrophobic emulsion for fracturing the reservoir containing a hydrocarbon phase, an emulsifier and an aqueous phase. Acid or water, or an aqueous solution of calcium chloride, sodium chloride, or potassium chloride salts can be used as the aqueous phase, and sodium sulfates of succinic acid diesters and Ci2-Cie alcohols and a hydroxyl salt of aliphatic amines with an alkyl residue can be used as an emulsifier. in the following ratio of components, vol.%:

Hydrocarbon liquid 13.3-19.4

Acid or water or

water solution of salts

CaCl2, NaCI, KCI80-85

Sodium salts of sulfo-amber diesters

acids and alcohols Ci2-Cie 0.5-1.5

Sol nokisla salt

aliphatic amines

with alkyl residue

Syu-S150,1-0,2

This emulsion at 120 ° C retains its properties and is destroyed only at 150 ° C.

The disadvantage of this composition is the impossibility of using it as a working fluid in formations with a temperature of 60-120 ° C, tj. within these limits, the emulsion is not destroyed, and hence its use is impossible. In addition, the specified emulsion contains scarce expensive chemical reagents: sodium salts of diesters of sulphate succinic acid and alcohols Ci2-Ci6, and also hydroxyl salt of aliphatic amines with an alkyl residue.

The aim of the invention is to create a hydrophobic emulsion that maintains thermal stability in the temperature range of 60-120 ° C for the time of its injection into the formation.

As a hydrocarbon liquid, an emulsion contains dehydrated degassed oil with a paraffin content of not more than 6% by weight, asphalt-resinous substances not more than 35% by weight with a density of 720,900 kg / m, viscosity at 20 ° C not more than 30 mPa s, and ferrochrome lignosulfonate is used as an emulsifier; fresh water or formation water or

hydrochloric acid of 22% concentration in the following ratio of ingredients, wt.%:

Dehydrated degassed oil with a density of 620-900 kg / m3, viscosity at

0-20 ° С not more than 30 MPa with and paraffin content not more than 6 wt.%, Asphalt-resinous substances not more than 35 wt.% 20.0-30 O Ferrochromo-lignosulfonate 0.01-1.0 Freshwater or formation water

5 or hydrochloric acid

22% concentration Else The positive properties of a hydrophobic emulsion include the simplicity and adaptability of its preparation; availability of initial reagents; ferrochrome lignosulfonate, which is part of the emulsion, belongs to the group of non-toxic compounds and does not have an allergenic effect. In the implementation of technological

5, the equipment does not corrode; the acid is in the internal phase of the emulsion and there is no direct contact of the acid with the oil-field equipment. Also developed

0 A hydrophobic emulsion can be used as a fracturing fluid with simultaneous chemical exposure to the formation rock.

Proposed Hydrophobic Emulsion

5 as an emulsifier Ferrochrome lignosulfonate (FHLS) is a product of the interaction of lignosulfonates with iron sulfate and sodium bichromate, in which chromium and iron are linked by macromolecules in the form of complex complexes. These complexes have the ability to reduce the surface tension at the water – oil interface and form strong structured protective films

5 counts an increase in emulsion stability. Depending on the concentration of FHLS (0.01-1.0 wt.%) In the emulsion, the temperature of its destruction is in the range of 60-120 ° C.

0 Introduced hydrophobic

emulsion as an emulsifier of ferro-chromo-lignosulfonate allows obtaining a system for treating a formation that is stable for the time required for injection into the formation and is capable of being destroyed in the temperature range of 60-120 ° C. The temperature of the destruction of emulsions depends on the concentration of the emulsifier, the more FHLS in the composition of the emulsion, the more durable structured films are formed on

phase boundary and, therefore, the emulsion will have greater heat resistance.

The hydrophobic emulsion developed is a reverse type emulsion, where the external phase is oil and the internal phase is water or an aqueous acid solution, and therefore no direct contact of the aqueous phase (acid solution) with the oilfield equipment takes place and its corrosion is significantly reduced.

The positive properties of the developed emulsion should also include the simple technology of its preparation, the availability and safety of the initial reagents and the long storage time, which is characterized by stability,

Chemicals needed to prepare a hydrophobic emulsion:

oil is commercially dehydrated, degassed with the following physicochemical characteristics: density from 720 to 900 kg / m3 with paraffin content up to b% and asphalt-resinous substances up to 35%, viscosity at 20 ° С to 30 mPa.c; water - fresh or reservoir; hydrochloric acid - content of hydrogen chloride 20-22% with the addition of a corrosion inhibitor TU 6-01-714- 77 (inhibited hydrochloric acid);

ferrochrome lignosulfonate (FHLS) —the product of the interaction of sulfite-alcohol bards of PRS or sulfite-yeast bast DMB with ferrous sulphate and sodium bichromat, in which chromium and iron are linked by macromolecules in the form of complex complexes; Dry powder belongs to the group of non-toxic compounds and does not have an allergenic effect. The reagent UkrGiproNIIneftU was developed 39-01-08-348-78, produces Karabulak chemical plant.

The proposed formulations are developed for the first time. To determine the optimal ratio of components, experiments were carried out according to examples 1-15, presented in table. 1. Compositions 1-15 are prepared as follows.

In the amount of oil calculated by the recipe, the required amount of emulsifier ferrochrome lignosulfonate (FHLS) is dissolved, and with vigorous stirring, the calculated amount of water or hydrochloric acid solution is introduced in 3-4 portions in portions. The mixing time of the emulsion composition is 30 minutes at a stirring speed on a mechanical stirrer I R-40-2500-4000 rpm,

In the study of compositions, stability, viscosity, temperature,

at which the emulsion is fully preserved, and the temperature at which the emulsion is destroyed. The viscosity of the hydrophobic emulsion was tested on a rotary

viscometer with internal rotating Rehotest-RV cylinder. Stability is estimated by the time during which the emulsion does not break down at 20 ° C.

0 The thermal stability of the emulsion was estimated by the temperature at which the emulsion was kept completely for 2-4 hours, i.e. the time required for carrying out the main and final works at the hydraulic fracturing and the temperature at which the emulsion was completely destroyed during the specified period. Visual observations of the separation of thermostatically controlled emulsion samples.

0 The results of laboratory studies are presented in Table. 1. The table shows that the most acceptable for fracturing by viscosity value (from 50 to 195 mPa.s) are the compositions with the following ratio of ingredients, wt.%: Hydrocarbon phase (dehydrated degassed oil) 20-30 Emulsifier ferrochromethylsulphonate ( FHLS) 0.01-1.0

Aqueous phase (fresh or reservoir water or

hydrochloric acid solution) 69.0-79.99 Comparative test results

5 compositions of the proposed hydrophobic emulsion and compositions of the prototype are presented in table. 2. From the table it can be seen that the proposed composition is the most suitable for a formation with a temperature of 60-120 ° C. The use of this hydrophobic emulsion will make it possible to effectively process formations and carbonate reservoirs in a large group of large oil fields in Western Siberia, Transcaucasia, etc., whose formation temperatures vary from 60-120 ° C. At the same time, hydraulic fracturing and processing of carbonate reservoirs will allow to transfer unprofitable low-yield

0 wells are profitable due to a multiple increase in their productivity.

Claims (1)

A hydrophobic emulsion for treating a formation containing a hydrocarbon fluid, an emulsifier and an aqueous phase, characterized in that, in order to maintain the thermal stability of the emulsion in the range of 60-120 ° C during its injection into the formation, the emulsion contains dehydrated hydrocarbon fluid degassed oil with a density of 720–900 kg / m with a viscosity of not more than 30 MPa-s at 20 ° C and a paraffin content of no more than bw wt.%, asphalt-resin substances not more than 35 wt.%, as an emulsifier ferrochromo lignosulfonate, and as a water film Ase - fresh or formation water or hydrochloric acid of 22% concentration with the following ratio of ingredients, wt.%: 0 Dehydrated degassed oil with a density of 720-900 mg / m, viscosity not more than 30 MPa-s at 20 ° C and paraffin content not more than 6 wt.%, Asphalt-resin substances not more than 35 wt.% 20.0-30.0 Ferrochrome lignosulfonate 0.01-1.0 Presna or Plastova water or hydrochloric acid 22% concentration Else Table 1 35 Tabl ia2