RU2806639C1 - Method for intensifying oil production from domanic deposits - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: in the method of intensifying oil production from Domanic deposits after perforation of the formation, the thickness of the perforated formation is determined, proppant with a concentration of 15.5-15.9 kg/m³ is pumped with a technical fluid - process water with a volume of 30-35 m³ per 1 m of the thickness of the perforated formation. Next, a liner filled with magnesium granules is lowered into the well opposite the perforation interval, then acid treatment is performed. Surfactant acid composition of “ПАКС” containing, wt.%: 22-25% solution of hydrochloric acid 90; surfactant 2, bottoms of butyl alcohols or isopropyl alcohol 3; water-soluble demulsifier 2; acetic acid of at least 80% concentration 3, in a volume of 1-1.1 m³ per 1 m of thickness of the perforated layer used as an acid composition. “ПАКС” is pressed into the formation with a hydrocarbon solvent with a volume of 0.5 m³ per 1 m of the thickness of the perforated formation, then the liner is raised to the wellhead. Next, proppant with a concentration of 16.7-16.9 kg/m³ is pumped with a technical fluid - technical water with a volume of 41-43 m³ per 1 m of perforated formation thickness. Next, a liner filled with magnesium granules is lowered into the well opposite the perforation interval. Then acid treatment is carried out, “ПАКС” is used as an acid composition in a volume of 1.4-1.7 m³ per 1 m of perforated formation thickness, “ПАКС” is pressed into the formation with a hydrocarbon solvent in a volume of 1 m³ per 1 m of perforated formation thickness. Then a technological holding period of 10-12 hours is carried out.

EFFECT: increase in the production rate of Domanic deposits by changing the molecular-surface properties of the Domanic deposit rock and reservoir fluids, the absence of a rapid drop in reservoir pressure, an increase in the formation coverage of the impact, uniformity of oil reserves production, and an increase in the oil displacement coefficient.

1 cl, 2 tbl, 5 ex

Description

The invention relates to the oil industry and can be used for the development and restoration of the flow rate of production wells, in particular the intensification of the influx of formation fluids in the low-permeability Domanikov reservoir, which has a permeability varying from several units to several hundred mD (10-6 μm ² ).

There is a known method for treating the bottomhole zone of an oil-bearing formation with a vapor-gas mixture of hydrogen and water, formed by the interaction of metal magnesium with 15-20% hydrochloric acid (I.T. Mishchenko. Borehole oil production. “Oil and Gas. 2007” UDC 622.276.5 page 253-256).

There is a known method for hydraulic fracturing of a productive formation (patent SU No. 1334806, IPC E21B 43/26, published on May 10, 1999), which includes creating a depression in the formation overlying or underlying the productive formation, which causes elastic compressive deformation, the subsequent creation of depression in the productive formation, causing its elastic deformation, and injection of fracturing fluid after pressure recovery. After the pressure is restored, the formation is re-drained, and the fracturing fluid begins to be injected at a bottomhole pressure that is at least 5 MPa below the formation pressure.

There is a known method for intensifying well operation (patent RU No. 2541974, IPC E21B 43/267, published on February 20, 2015 in Bulletin No. 5), including test injection of fracturing fluid and a pack of fracturing fluid with proppant, adjusting the fracturing design and carrying out the main fracturing process. In low-permeability reservoirs with an absolute permeability of no more than 1 mD, the main hydraulic fracturing process is carried out with the injection of a buffer fluid at the rate of 1.0-3.0 m ³ per 1 ton of proppant, using proppant fractions that include only a fine fraction with a dimension no larger than 30/60 mesh with a final proppant concentration of no more than 300 kg/m ³ , during pumping the liquid flow rate is maintained at 3.5 m ³ /min or more, and the concentration of the gelling agent is set to no more than 2 kg/m ³ , with a final under-distribution of the mixture in a volume of 0 .1-0.5 ^m3 .

The disadvantage of the above known methods is their low efficiency when used to intensify the work of a well that has opened a formation with a low-permeable Domanikov reservoir, since an insufficient fracture length is created due to the lack of an integrated approach, there is no acid treatment that reduces the viscosity of formation fluids, which is a limiting factor in increasing well productivity, thereby not producing the full potential of the low-permeability formation.

The closest is the method of intensifying the work of a well that has penetrated a low-permeability formation (patent RU No. 2603986, IPC E21B 43/267, published on December 10, 2016 in Bulletin No. 34), including test injection of fracturing fluid and a pack of fracturing fluid with proppant, adjusting the fracturing design and carrying out the main hydraulic fracturing process using proppant fractions, including only a small fraction with a dimension no larger than 30/60 mesh, with a final proppant concentration of no more than 250 kg/m ³ , with a final under-sale of the mixture in a volume of 0.1-0.5 m ³ . In low-permeability Domanikov reservoirs, which have an absolute permeability of no more than 1 mD, the formations are perforated with a perforation system that creates holes with a diameter of at least 20 mm, equipment designed for surface pressures during processing of up to 100 MPa is used, and preliminary acid treatment is carried out to initiate and etch out cracks from calculating at least 2 m ³ of thickened acid per 1 linear m of formation; when carrying out the main hydraulic fracturing process, proppant concentrations are created in the range from 100 to 250 kg/m ³ with an initial concentration value of no more than 100 kg/m ³ ; when pumping, the proppant concentration is increased from in increments of no more than 30 kg/m ³ , not exceeding the value at the final stage of 250 kg/m ³ with adjustment of concentration values depending on the increase in wellhead pressure by adjusting the fluid flow, but not exceeding wellhead pressure values of 100 MPa.

The disadvantage of the known methods is their low efficiency when used to intensify the work of a well that has opened a formation with a low-permeability Domanik reservoir, since the acid treatment used does not sufficiently reduce the high viscosity of formation fluids, which is a limiting factor in increasing the productivity of wells, thereby not producing the full potential of the low-permeability formation . It should also be noted that the coverage of the impact of acid treatment is not high enough, due to the lack of creation of deep penetration cracks.

The technical result of implementing the method is to increase the production rate of the Domanikov deposits by changing the molecular-surface properties of the Domanikov deposits rock and reservoir fluids in the absence of a rapid drop in reservoir pressure, increasing the formation coverage of the impact, uniformity of oil reserves production, and increasing the oil displacement coefficient.

The technical result is achieved by a method of intensifying oil production from Domanik deposits, including perforation of the formation with a perforation system, acid treatment, and proppant injection.

What is new is that after perforation of the formation, the thickness of the perforated formation is determined, before acid treatment, proppant with a concentration of 15.5-15.9 kg/m ³ is pumped with a technical fluid - process water with a volume of 30-35 m ³ per 1 m of the thickness of the perforated formation, then A liner filled with magnesium granules is lowered into the well opposite the perforation interval, then an acid treatment is performed, the surfactant acid composition PAX is used as an acid composition, containing, wt.%: 22-25% hydrochloric acid solution - 90, surfactant substance - 2, bottoms of butyl alcohol or isopropyl alcohol - 3, water-soluble demulsifier - 2, acetic acid of at least 80% concentration - 3, in a volume of 1-1.1 m ³ per 1 m of thickness of the perforated formation, pressed into the formation surfactant acid composition PAX with a hydrocarbon solvent with a volume of 0.5 m ³ per 1 m of thickness of the perforated formation, then the liner is raised to the wellhead, then proppant with a concentration of 16.7-16.9 kg/m ³ is pumped with technical fluid - industrial water with a volume of 41-43 m ³ per 1 m of thickness of the perforated formation, then a liner filled with magnesium granules is lowered into the well opposite the perforation interval, then acid treatment is performed, the surfactant acid composition PAX is used as an acid composition in a volume of 1.4-1, 7 ^m3 per 1 m thickness of the perforated formation, the surface-active acid composition of PAX is forced into the formation with a hydrocarbon solvent with a volume of 1 ^m3 per 1 m thickness of the perforated formation, then a technological holding period is carried out for 10-12 hours.

The method is implemented using the following reagents:

- proppant - obtained in the form of granules with a cyclometric density of 1.1-2.5 g/cm ³ and dimensions of 0.2-4.0 mm, from a mixture of powdered aluminosilicate raw materials, silicate microspheres and a binder - a mixture of 3% aqueous solution carboxymethylcellulose or methylcellulose, or technical lignosulfonates, silicate microspheres and nanoparticles of alkaline earth metal oxides; produced under patent RU No. 2472837, IPC C09K 8/80, C04B 35/22, publ. 01/20/2013, in the bulletin. No. 2;

- process liquid - - process water;

- magnesium granules - grade MG-90 in ingots of 100-150 grams, average ingot size: 70x40x30 mm, produced in accordance with GOST 804-93;

- surface-active acid composition of PAX includes (wt.%) 22-25% solution of hydrochloric acid - 90, surfactant type ML-81B, FLEC-2, bottoms of butyl alcohols or isopropyl alcohol - 3, water-soluble demulsifier - 2, acetic acid of at least 80% concentration - 3. PAX is produced in accordance with TU 2458-156-00147588-2007 and is a transparent liquid from light brown to dark brown, mass fraction of hydrogen chloride - 20- 22%, interfacial tension at the boundary with oil no more than 0.15 mN/m, pour point - minus 25°C;

- various reagents, which are a mixture of hydrocarbons of the saturated aliphatic and aromatic series, can be used as a hydrocarbon solvent. For example, hydrocarbon solvent produced by Elkhovskaya NPU in accordance with TU 19.20.23-030-60320171-2019, industrial solvent in accordance with TU 0258-007-60320171-2016, distillate 30/125 in accordance with TU 2411-139-05766801-2007 or toluene according to GOST 14710- 78 or its equivalents. The use of any hydrocarbon solvent leads to the same technical result.

The essence of the method is as follows.

The formation is perforated using a perforation system.

The thickness of the perforated layer is determined.

Before acid treatment, proppant with a concentration of 15.5-15.9 kg/m ³ is pumped with a technical fluid - technical water with a volume of 30-35 m ³ per 1 m of perforated formation thickness. Cracks are created in the near-well zone, the first stage of development of the crack in length occurs.

Next, a liner filled with magnesium granules is lowered into the well opposite the perforation interval.

Then an acid treatment is performed, the surfactant acid composition PAX is used as an acid composition, containing, wt.%: 22-25% solution of hydrochloric acid - 90, surfactant - 2, bottoms of butyl alcohols or isopropyl alcohol - 3, water-soluble demulsifier - 2, acetic acid of at least 80% concentration - 3, in a volume of 1-1.1 m ³ per 1 m of perforated layer thickness.

The surface-active acid composition PAX is forced into the formation with a hydrocarbon solvent in a volume of 0.5 m ³ per 1 m of the thickness of the perforated formation.

When a surfactant acid composition passes through magnesium granules, an exothermic process occurs that heats the acid composition, which enhances the effect of acid treatment, the molecular surface properties of the Domanikov deposits rock, and formation fluids change, while a rapid drop in formation pressure does not occur, since the necessary viscosity of the acid composition, reaching 86.4 mPa*s. The viscosity of formation fluids decreases and the intensification of the influx of formation fluids in the low-permeability Domanikov reservoir increases.

The liner is then lifted to the wellhead.

Next, proppant with a concentration of 16.7-16.9 kg/m ³ is pumped with a technical fluid - technical water with a volume of 41-43 m ³ per 1 m of perforated formation thickness. The penetration depth increases and thereby creates a network of cracks with maximum development in length.

Next, a liner filled with magnesium granules is lowered into the well opposite the perforation interval.

Then acid treatment is carried out; the surface-active acid composition PAX is used as an acid composition in a volume of 1.4-1.7 m ³ per 1 m of perforated formation thickness.

The surface-active acid composition of PAX is forced into the formation with a hydrocarbon solvent with a volume of 1 m ³ per 1 m of the thickness of the perforated formation.

Repeating the acid treatment allows the treatment to cover a larger area by penetrating deeper channels created by secondary hydraulic fracturing.

Then a technological holding period is carried out for 10-12 hours.

Examples of method implementation.

The formation was perforated using a perforation system. The thickness of the perforated formation was determined to be 15 m. Before acid treatment, proppant with a concentration of 15.5 kg/m ³ was pumped with process water with a volume of 450 m ³ . Next, a liner filled with magnesium granules was lowered into the well opposite the perforation interval. Then the surfactant acid composition PAX was pumped in a volume of 15 m ³ . The surface-active acid composition of PAX was forced into the formation with a hydrocarbon solvent, which used toluene, with a volume of 7.5 m ³ . The liner was then raised to the wellhead. Next, proppant with a concentration of 16.7 kg/m ³ was pumped with process water with a volume of 615 m ³ . Next, a liner filled with magnesium granules was lowered into the well opposite the perforation interval. Then the surfactant acid composition PAX was pumped in a volume of 21 m ³ . The surfactant acid composition PAX was forced into the formation with a hydrocarbon solvent with a volume of 15 m ³ . Then a technological holding period of 10 hours is carried out.

Afterwards, research was carried out to determine the oil flow rate. The research results showed that the oil production rate was 17 tons/day, the increase in oil production rate was 4 tons/day (example 1, tables 1, 2).

Other examples of the method are performed similarly; their conditions are given in table. 1 (examples 2-5), the results are in table. 2 (examples 2-5).

Table 1 - Conditions for implementing the method for intensifying oil production from Domanik deposits No. Thickness of perforated layer, m Proppant concentration, kg/ ^m3 Volume of technical fluid, m ³ Volume of acid composition PAX, m ³ Volume of hydrocarbon solvent, ^m3 Proppant concentration, kg/ ^m3 Volume of technical fluid, m ³ Volume of acid composition PAX, m ³ Volume of hydrocarbon solvent, ^m3 Hydrocarbon solvent
TU 19.20.23-030-60320171-2019 Industrial solvent TU 0258-007-60320171-2016 Distillate 30/125 Toluene Hydrocarbon solvent Industrial solvent Distillate 30/125 Toluene 1 15 15.5 450 15 7.5 16.7 615 21 15 2 16 15.9 560 17.6 8 16.9 688 27.2 16 3 12 15.8 396 12 6 16.8 504 19.2 12 4 21 15.9 714 23.1 10.5 16.9 882 33.6 21 5 18 15.8 594 18 9 16.7 756 30.6 18

Table 2 - Results of implementing the method for intensifying oil production from Domanik deposits. Average oil flow rate, t/day No. Up to the method After the method Growth 1 13 17 4 2 16 21.1 5.1 3 eleven 15.4 4.4 4 17 23.8 6.8 5 18 22.9 4.9

When the concentration of the proppant pumped before the first injection of the surfactant acid composition PAX is less than 15.5 kg/m ³ , and also when the concentration of the proppant pumped after the first injection with a hydrocarbon solvent is less than 16.7 kg/m ³ , rapid closure of cracks is observed, as a result, the effectiveness of PAX is reduced.

When the concentration of the proppant pumped before the first injection of the surfactant acid composition PAX is more than 15.9 kg/m ³ , as well as when the concentration of the proppant pumped after the first injection with a hydrocarbon solvent is more than 16.9 kg/m ³ , there is a possibility of water breakthrough from water-oil contact.

When the volume of proppant injected before the first injection of the surfactant acid composition PAX, with technical fluid is less than 30 m ³ per 1 m of thickness of the perforated formation, as well as when the volume of proppant injected after the first injection with a hydrocarbon solvent, with technical fluid is less than 41 m ³ per 1 m thickness of the perforated layer reduces the likelihood of obtaining cracks of the required length.

When the volume of proppant injected before the first injection of the surfactant acid composition PAX, with technical fluid, is more than 35 m ³ per 1 m of thickness of the perforated formation, as well as when the volume of proppant injected after the first injection with a hydrocarbon solvent, with technical fluid is more than 43 m ³ per 1 m in thickness of the perforated formation, the critical pressure may be exceeded, upon reaching which the clay screens, which act as separators of oil-saturated formations from water-saturated ones, may rupture, or the rate of change in the size of the crack may be exceeded, which may lead to hydrodynamic contact of the formations with production or injection wells. With such contact, the water cut in well production sharply increases and the current fluid production decreases.

When the volume of surface-active acid composition PAX during the first injection is less than 1 m ³ , as well as during the second injection less than 1.4 m ³ per 1 m of thickness of the perforated formation, the effectiveness of the interaction between the rock and the acid composition decreases.

When the volume of surface-active acid composition PAX during the first injection is more than 1.1 m ³ , as well as during the second injection more than 1.7 m ³ per 1 m of thickness of the perforated formation, the quality of the acid treatment is reduced, because the acid composition continues to react instantly in the same place. The acid treatment process becomes uncontrollable and does not achieve its goal.

Thus, the proposed method increases the production rate of the Domanikov deposits by changing the molecular-surface properties of the Domanikov deposits rock and formation fluids in the absence of a rapid drop in reservoir pressure, increasing the formation coverage of the impact, uniformity of oil reserves production, and increasing the oil displacement coefficient.

Claims (1)

A method for intensifying oil production from Domanik deposits, including perforation of the formation with a perforation system, acid treatment, injection of proppant, characterized in that after perforation of the formation the thickness of the perforated formation is determined, before acid treatment, proppant is pumped in with a concentration of 15.5-15.9 kg/m ³ with technical liquid - technical water with a volume of 30-35 m ³ per 1 m of thickness of the perforated formation, then a liner filled with magnesium granules is lowered into the well opposite the perforation interval, then acid treatment is carried out, the surfactant acid composition PAX is used as an acid composition, containing, wt. .%: 22-25% solution of hydrochloric acid 90; surfactant 2, bottoms of butyl alcohols or isopropyl alcohol 3; water-soluble demulsifier 2; acetic acid of at least 80% concentration 3, in a volume of 1-1.1 m ³ per 1 m thickness of the perforated formation, the surface-active acid composition of PAX is forced into the formation with a hydrocarbon solvent in a volume of 0.5 m ³ per 1 m thickness of the perforated formation , then the liner is raised to the wellhead, then proppant with a concentration of 16.7-16.9 kg/m ³ is pumped with technical fluid - technical water with a volume of 41-43 m ³ per 1 m of the thickness of the perforated formation, then it is lowered into the well opposite the perforation interval liner filled with magnesium granules, then acid treatment is carried out, the surface-active acid composition PAX is used as an acid composition in a volume of 1.4-1.7 m ³ per 1 m of thickness of the perforated formation, the surface-active acid composition PAX is forced into the formation with a hydrocarbon solvent with a volume of 1 m ³ per 1 m of thickness of the perforated layer, then a technological holding period is carried out for 10-12 hours.