RU2525399C1 - Acid emulsion for bottomhole formation zone - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: acid emulsion for processing bottomhole formation zone comprises the following components wt %: solvent - reagent "ИТПС-010К" - 13.0-27.7, emulsifier - reagent "ИТПС-804Э" - 4.5-10.0, hydrochloric acid making the rest. Acid emulsion can comprises extra hydrofluoric acid in amount of 4.0-10.0 wt % and viscosity regulator in amount of 0.1-5.0 wt %.

EFFECT: high efficiency and compatibility with formation water and oil.

3 cl, 4 tbl, 28 ex

Description

The invention relates to the oil industry and can be used for acid treatment of the bottomhole formation zone, represented by heterogeneous permeability carbonate or terrigenous reservoirs.

There is a method of treating a bottomhole formation zone, composed of carbonate rocks with hard-to-recover oil reserves, pumping an emulsion containing hydrochloric acid with a hydrocarbon solvent with a solvent-hydrochloric acid ratio of 25-35% and 65-75%, respectively, and an emulsifier (see RF Patent No. 2288358, MKI E21B 43/27, publ. 2006).

This composition is not effective enough due to the inconstancy of the rheological properties of the resulting emulsions.

A known method of processing the bottom-hole zone of the formation using a reverse oil emulsion, containing in vol.%: Hydrocarbon fluid - 26,0-40,0, oil-soluble nitrogen-containing emulsifier Sonkor-9601 or Sonkor-9701 - 0,4-5,0, an aqueous solution inhibited 10% hydrochloric acid or clay acid or an aqueous solution of 1-10% calcium chloride or sodium chloride - the rest (see RF Patent No. 2252515, MKI E21B 43/27, publ. 2005).

The known method involves the use of inverse oil emulsion of increased density, which reduces its penetration into the reservoir and prevents the processing of the intervals of the formation remote from the well.

Closest to the proposed invention in technical essence and the achieved result is a method of treating the bottom-hole zone of the well by injecting a reverse oil-emulsion emulsion containing in vol.%: 40-42 oil paraffin solvent (distillate), 5-8 of the YALAN-E-1 emulsifier, the rest is a 22-24% aqueous solution of inhibited hydrochloric acid (see RF Patent No. 2304710, MKI E21B 43/27, publ. 2007).

The disadvantage of the composition is the small depth of penetration of the composition into the reservoir due to the high rate of dissolution of the rock of the reservoir, the occurrence of mudding sediments, incompatibility with oil in the presence of iron (III) ions and unregulated viscosity.

The aim of the invention is the development of an acidic emulsion for treating the bottom-hole zone of an oil reservoir, which is highly effective by slowing down the rate of reaction of the acid with the rock of the reservoir, increasing the degree of coverage by treatment of the reservoir, preventing and removing clogging deposits, and also being compatible with formation water and oil.

This goal is achieved by creating an acidic emulsion for treating the bottom-hole zone of an oil reservoir, including a solvent, emulsifier and hydrochloric acid, moreover, it contains ITPS-010K reagent as a solvent, ITPS-804E reagent as an emulsifier, with the following ratio of components, wt.% :

Reagent ITPS-010K  13.0-27.7 Reagent ITPS-804E  4,5-10,0 Hydrochloric acid  rest.

In embodiments of the preparation of the emulsion, it may contain hydrofluoric acid in an amount of 4.0-10.0 wt.% And a viscosity regulator in an amount of 0.1-5.0 wt.%.

The reagent ITPS-010K is a composite mixture of surfactants in an aromatic solvent, a liquid from light yellow to dark brown in color with a density at 20 ° C of 750 kg / m ³ , TU-2458-014-27913102-2010.

Reagent ITPS-804E - is a composite mixture of amino compounds with carbohydrate aldehydes in an aqueous aromatic solvent, a light yellow to dark brown liquid with a density at 20 ° C of 900 kg / m ³ , TU 2458-018-27913102-2010. It is an emulsifier and has the properties of an iron stabilizer.

To prepare an acidic emulsion, the following are used as hydrochloric acid:

- inhibited hydrochloric acid according to TU 2458-264-05765670-99 with amendment 1, TU 2112-131-05807960-97 of 10.0-25% concentration, GOST 857-95;

- hydrofluoric acid according to GOST 10484-78, TU 6-09-2622-88.

As a viscosity regulator, use the reagent ITPS-8043K according to TU 2458-01827913102-2010.

The proposed acid composition can be prepared both in industrial production and immediately before use by sequentially dissolving the components of the emulsion in hydrochloric acid in the claimed amounts.

The proposed acidic emulsion is a water-in-oil emulsion.

We give examples of the preparation of acidic emulsions, the results are presented in table 1.

Example 1 (claimed emulsion)

While stirring with a mechanical stirrer, 6.0 g of ITPS-804E reagent is added to 75.0 g of hydrochloric acid, then 19.0 g of ITPS-010K reagent is added, stirring is continued until a homogeneous emulsion is formed (see table 1, example 1).

Examples 2, 4, 9, 13, 18, 26 are prepared analogously to example 1 without the addition of a viscosity regulator.

Example 3. When stirring with a mechanical stirrer, 6.0 g of ITPS-804E reagent is added to 75.0 g of hydrochloric acid, then 19.0 g of ITPS-010K reagent and a viscosity regulator ITPS-804 ZK in an amount of 0.1 g are added, stirring is continued until formation homogeneous emulsion (see table 1, example 3).

Examples 5-8, 10-12, 14-17, 19-25, 27 are prepared in a similar manner, changing the types of components and their content in the emulsion in the claimed amounts.

Example 28 (prototype).

7.0 g of Yalan-E-1 emulsifier is dissolved in 51.0 g of hydrochloric acid (23% aqueous solution), a solvent of petroleum paraffins is added - distillate in an amount of 42.0 g and stirred for 5 minutes (see table 1, example 28).

The inventive acid emulsion is intended to intensify the flow and injectivity of wells during operations when processing the bottom-hole formation zone. The chemical components contained in the emulsion are capable of providing a washout of the formation from asphaltene-tar-paraffin deposits, and to prevent precipitation of iron compounds.

The rate of interaction of the acidic emulsion with the formation rock is reduced due to the content of surfactants and polymer additives in the emulsion. Also, the reverse type, i.e. the inorganic phase inside the organic phase, which slows down the release of acid for reaction with the formation rock. A significant decrease in the rate of reaction with the formation rock is also provided by an increase in the viscosity of the emulsion. The combined effect of the selected components of an acid emulsion of complex action will lead to an increase in the coverage of the formation with acid exposure.

Table 1 №№ p.p The content of the components of the emulsion, wt.% Viscosity, MPa * s The dissolution rate of marble, kg / m ² * h Washing paraffin effectiveness,% Reagent ITPS-010K Reagent ITPS-804E Acid Viscosity regulator one 2 3 four 5 6 7 8 one 19.0 6.0 75.0 HCl - thirty 9.965 84.5 2 13.0 4.5 82.5 HCl - 25 10.034 91.0 3 19.0 6.0 75.0 HCl 0.1 53 7.416 77.1 four 13.0 6.0 81.0 HCl - 34 9.501 85.8 5 27.7 10.0 62.3 HCl 1.0 90 4.565 65.9 6 * 19.0 6.0 71.0 HCl + 4.0 HF 0.2 58 7.238 70.3 7 19.0 6.0 75.0 HCl 0.3 64 6.614 66.0 8 19.0 6.0 75.0 HCl 0.4 71 6.572 61.4 9 15.0 10.0 75.0 HCl - 36 9.820 82.6 10 19.0 6.0 75.0 HCl 0.5 77 6.503 55.7 eleven* 19.0 6.0 70.0 HCl + 5.0 HF 0.6 82 6.147 76.1 12 19.0 6.0 75.0 HCl 0.7 85 6.090 73.0

13 15.0 5.0 80.0 HCl - 28 10.088 91.1 fourteen* 19.0 6.0 75.0 HCl 0.8 88 6.044 75.5 fifteen* 19.0 6.0 75.0 HCl 0.9 90 6.002 63.9 16* 19.0 6.0 75.0 HCl 1.0 95 5.985 51.7 17 19.0 6.0 75.0 HCl 1.5 101 5.988 50.4 eighteen 25.0 9.0 66.0 HCl - 39 9.467 96.2 19* 19.0 6.0 65.0 HCl + 10.0 HF 2.0 150 3.771 54.4 twenty* 19.0 6.0 67.0 HCl + 8.0 HF 2.5 179 3.120 48.6 21 * 19.0 6.0 71.0 HCl + 4.0 HF 3 210 3.019 49.0 22 * 19.0 6.0 65.0 HCl + 10.0 HF 3.5 263 2.900 50.2 23 * 19.0 6.0 70.0 HCl + 5.0 HF 4.0 290 2.546 45.1 24 * 19.0 6.0 65.0 HCl + 10.0 HF 4.5 334 2.402 40.3 25 13.0 4.5 82.5 HCl 5.0 380 2.359 45.3 26 20.0 4.5 75.5 HCl - 35 9.989 88.9 27 * 18.0 4.5 73.5 HCl + 4.0HF 5.0 340 2.347 54.7 28 prototype 42.0 paraffin solvent 7.0 emulsifier, "Yalan-E-1" 51.0 HCl 22 10.117 23.6 * - compositions used for the treatment of terrigenous rocks.

Emulsion viscosity is determined on a Lamy Rheomat RM200 rotational viscometer. Measurements are carried out at a shear rate of 511 s ^-1 .

The dissolution rate of carbonates (marble) is evaluated by the following method. A marble cube is weighed to the second sign, and the cube volume and density are calculated from the linear dimensions. The average density of marble used is 2.5 kg / m ³ . A marble cube suspended on a thread is lowered into the test emulsion and after 1 minute it is removed, washed with water, dried and weighed. Determine the mass loss and calculate the reaction rate of the compounds in kg / m ² h. According to the data presented in table 1, the reaction speed with marble of the claimed emulsions is inversely proportional to their viscosity and lower than the reaction speed of the prototype.

Determination of washing efficiency is carried out in dynamic conditions, for which samples of asphalt-resin-paraffin deposits (ASPO) weighing 2 g are placed in stainless steel baskets and suspended in a layer of 100 ml of a prepared emulsion in a 250 ml plastic bottle on a wire. Mix the contents of the bottles on the device PE-6410M for 4 hours at room temperature. Then the samples are removed, rinsed with water, dried in air and weighed. Washing efficiency is defined as the ratio of the loss of mass of the sample to its initial weight in percent. For the study, a paraffin test sample was used from well 15265 of the Novo-Elkhovsky field of the Republic of Tatarstan.

According to the results shown in table 1, it is seen that the inventive acid emulsion has an effective detergent activity against asphalt-resin-paraffin deposits. When comparing the results obtained, it is seen that the proposed acid emulsion has a higher detergent efficiency of ARPD compared to the prototype by 16.7-72.6%.

To determine the effectiveness of using the composition in heterogeneous permeability formations, experiments are conducted to change the viscosity and dissolution rate of marble when mixing the inventive acidic emulsion with formation fluids such as formation water and oil.

The research results are shown in table 2.

table 2 Initial viscosity, cPz The reaction rate, kg / (m ² h) Viscosity, MPa * s The reaction rate, kg / (m ² h) Viscosity, MPa * s The reaction rate, kg / (m ² h) Viscosity,
MPa * s The reaction rate, kg / (m ² h) 30% water 50% water 100% water thirty 9.965 45 8.440 52 7.052 70 6.981 45 8.353 63 6.992 72 6.807 85 5.605 125 3.944 - - 130 3.704 162 6.116 30% oil 50% oil 100% oil thirty 9.965 6 13.571 7 14.169 10 10.674 45 8.353 6 12.660 5 15.772 5 12.211 125 3.944 - - 8 9.912 eleven 11.106

The results show that when the acid emulsion is diluted with water, the viscosity increases significantly, which allows you to temporarily reduce the permeability of water-saturated layers. At the same time, the response rate with marble is reduced. When the injected emulsion enters low-permeable oil-saturated interlayers, the viscosity of the acid emulsion decreases, and the reaction rate with marble increases. Thus, the inventive acid emulsion is a highly selective reagent for the treatment of heterogeneous permeability formations. After redistribution of the filtration flows and holding to the reaction, the emulsion decomposes due to the loss of acid concentration and emulsion viscosity, with the formation of mobile inorganic and hydrocarbon phases, which are easily washed out of the formation, which is most effective when processing bottom-hole zones of production wells.

Testing for oil compatibility with the claimed emulsion is carried out in order to record the formation or absence of tarry precipitates according to the method described in the document “Joint TNK-BP standards for compliance with quality control during hydraulic fracturing and acid treatments”. 50 ml of an emulsion with dissolved ferric chloride in an amount of 0.78 g are poured into a glass graduated test tube with a screw cap in the amount of 3000 ppm of iron (III) ions. Then, 50 ml of the test oil is poured into the test tube, the stopper is screwed and mixed with vigorous shaking for 30 seconds. After keeping for 0.5 h, the contents of the tube are poured through a filter with a mesh size of 0.200 mm and the presence of sediment on the filter is recorded. Testing is considered satisfactory in the absence of tar on the filter. When testing use oil 5 NGDU Republic of Tatarstan. The test results are shown in table 3.

Table 3 №№ p.p The emulsion from table 1 The presence of tar Oil samples Lenino-Gorskneft Yamash Neft Elkhov-Neft Bavly-Neft Nurlat-oil one one No draft No draft No draft No draft No draft 2 3 No draft No draft No draft No draft No draft 3 12 No draft No draft No draft No draft No draft four 16 No draft No draft No draft No draft No draft 5 25 No draft No draft No draft No draft No draft 6 prototype 28 Sediment Sediment Sediment Sediment Sediment

According to table 3 it is seen that the inventive emulsion is fully compatible with various samples of oil, the prototype forms resinous sediments with each oil presented.

To prove the criterion of "industrial applicability" we give examples of the effects of the proposed emulsion on samples of carbonate and terrigenous cores. Experiments on the effects of the inventive emulsion on a core sample are carried out on the installation UIPK-1M. Permeability measurements of core samples are carried out before and after treatment with emulsions. First, core samples are saturated with formation water, then with oil, and then again with formation water to the residual oil content in the sample. Then, three pore volumes of the test emulsion are pumped through the core and the change in permeability is measured by passing formation water until a constant flow rate is established. In experiments, oil and produced water are used by NGDU Elkhovneft (Republic of Tatarstan).

The change in permeability is calculated by the formula:

E = 100-K ¹ / K ² * 100%,

where: K ¹ - permeability before processing, μm ² ;

K ² - permeability after processing, μm ² .

The experimental results are shown in table 4.

Table 4 No. Core The emulsion from table 1 Permeability to processing, microns ² Permeability after processing, μm ² The increase in permeability,% one Carbonate one 0.000068 0.00334 98.0 2 Terrigenous 6 0.0050 0.0064 21.9 3 Carbonate 28 0.000076 0.00017 55.3

The data in table 4 show that the inventive emulsion increases the permeability of carbonate rock is higher by 42.7% compared with the prototype.

Acidic emulsion has complex properties due to the multifunctional chemical orientation of its constituent components. When using the inventive emulsion, directed deep processing of the bottom-hole zone of the formation, represented by heterogeneous permeability carbonate or terrigenous rocks, prevents precipitation and removes asphalt-tar-paraffin deposits, and the proposed emulsion is compatible with formation fluids.

Claims (3)

1. An acidic emulsion for treating the bottom-hole zone of an oil reservoir, including a solvent, emulsifier and hydrochloric acid, characterized in that it contains ITPS-010K reagent as a solvent, and ITPS-804E reagent as an emulsifier in the following ratio of components, wt.% :
reagent ITPS-010K 13.0-27.7 reagent ITPS-804E 4,5-10,0 hydrochloric acid rest 2. The acid emulsion according to claim 1, characterized in that it further comprises hydrofluoric acid in an amount of 4.0-10.0 wt.%. 3. The acid emulsion according to claim 1, 2, characterized in that it further comprises a viscosity regulator in an amount of 0.1-5.0 wt.%.