RU2322476C1 - Liquid for hydraulic seam rupture - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: invention relates to technological compositions used for increasing permeability of productive seams by carrying out hydrorupture of seam and can be used in extraction of gas and oil. Proposed liquid for hydraulic rupture of seam comprises the following components, wt.-%: potassium chloride, 6.00-7.00; sulfacell of sort 800, 1.30-2.00; aluminum sulfate, 0.15-0.80; disolvan, 0.03-0.05, and water, 90.15-92.52. Invention provides deceasing filtration, enhancing sand-retaining capacity, retention of filtration indices of critical zone of seam, availability of chemical reagents.

EFFECT: improved and valuable technical properties of liquid.

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Description

The invention relates to the field of oil and gas production, in particular to technological compositions used to increase the permeability of productive formations by means of hydraulic fracturing, and can be used in oil and gas companies.

Known fluid for hydraulic fracturing (hydraulic fracturing) containing components, wt.%: Sulfite-alcohol yeast vinasse 31,72-39,76; potassium chloride 3.37-6.92; polyacrylamide 0.05-0.12; ML surfactant 0.3-0.15 and produced water the rest (RF patent No. 1710710).

The disadvantage of this composition is the low sand holding capacity. With high rheological properties, this fluid retains 10% of the sand. This fluid does not have a destructive ability and is not completely removed from the reservoir, which leads to a decrease in the permeability of the reservoir after hydraulic fracturing.

Closest to the claimed composition of the fluid is a hydraulic fracturing fluid (RF patent No. 2138633). The liquid consists of technical lignosulfonate modified with hexamethylenetetramine and carbamide, potassium chloride, and as an additive it contains a trivalent metal salt - aluminum sulfate - and produced water.

However, this fluid has the following disadvantages: the fluid reduces the permeability of the bottom-hole zone of the formation after hydraulic fracturing, since technical lignosulfonates penetrate into the pore space of reservoir rocks and the permeability recovery coefficient reaches 37.5%, the sand-holding ability was not determined, although the data on static shear stress measurements (SNA) indicate low sand holding capacity. In addition, the multicomponent nature of this fluid makes it difficult to prepare and limits its use in hydraulic fracturing.

The task consisting in the creation of the invention is to increase the productivity of wells after hydraulic fracturing.

The technical result achieved by this invention is the creation of a water-based solution for hydraulic fracturing with low filtration and high sand retention ability, preserving the filtration characteristics of the bottom-hole formation zone, a small component, from available chemical reagents.

The task and technical result are achieved in that the fluid for hydraulic fracturing, including potassium chloride, aluminum sulfate and water, in contrast to the prototype additionally contains sulfacell (grade 800), surfactant is disolvan, in the following ratio, wt. %:

potassium chloride 6.00-7.00 sulfacell (grade 800) 1.30-2.00 aluminum sulfate 0.15-0.80 disolvan 0.03-0.05 water 92.52-90.15

The inventive hydraulic fracturing fluid differs from the prototype in that it contains sulfacellum, which acts as a gel-forming base, and a surfactant, disolvan, which acts as a hydrophobizing agent and prevents the penetration of the aqueous phase of the hydraulic fracturing fluid into reservoir rocks. A crosslinking agent is aluminum sulfate. When aluminum sulfate is dissolved in water, it decomposes into ions and cross-link the sulfacell. As a result, a strong gel is formed.

The following components were used to prepare the inventive hydraulic fracturing fluid.

Potassium Chloride (KCl) according to GOST 4239-77, crystalline white powder (you can use technical potassium chloride - a waste product of potash fertilizers).

Sulfacell according to TU 2231-013-32957-01, white powder is used to stabilize and reduce the filtration rate and as a gelling agent. CJSC “Polycell” is produced in Vladimir.

Aluminum sulfate according to GOST 12966-86, white powder, highly soluble in water. Manufacturer of Aluminum of Kazakhstan OJSC Kazakhstan.

Disolvan 4490 is a surfactant. It is a bright liquid with a density of 950 to 970 kg / m ³ . The manufacturer is Akorgan Germany.

The technology for preparing fluid for hydraulic fracturing under laboratory conditions is as follows: the calculated amount of potassium chloride is introduced into the water, mixed until complete dissolution, and then sulfacell, the estimated amount of aluminum sulfate and disolvan are introduced. Next, the liquid is mixed on a mixer for 30 minutes at a speed of 500-1000 rpm and left alone for 2-3 hours in order to form a gel.

The gel parameters were determined using standard instruments, the static shear stress was determined by the SNS-2 instrument, the plastic viscosity and dynamic shear stress were determined by the FANN-35A rotational viscometer.

Sand holding capacity was determined by introducing 100 g of proppant into 100 ml of liquid. With stirring, the proppant was evenly distributed in the liquid, and sedimentation stability was determined in the measuring cylinder (table 1). The high sand-holding ability of the fluid ensures the success of hydraulic fracturing, as there is no premature proppant loss before the hydraulic fracturing process. The recovery coefficient of permeability after the penetration of hydraulic fracturing fluid into a rock sample with a permeability of 31.8 · 10 ^-3 was 73.1% (Table 2).

Due to the improvement of technological parameters, the efficiency of the inventive fluid during hydraulic fracturing is increased and the filtration characteristics of the bottomhole formation zone are maintained, which ensures an increase in the current production of production wells.

Table 1 Composition and properties of hydraulic fracturing fluids Gel performance Composition, wt.% Plastic viscosity, μ, MPa · s Static shear stress Θ, 1/10, dPa Filtration, cm ^3/30 min Sand holding capacity, h Conditional viscosity, s The hydraulic fracturing fluid of the claimed 34.0 77.0 / 86.0 4.0 12.0 25.0 Potassium chloride 6.00-7.00 Sulfacell (grade 800) 1.30-2.00 Aluminum sulphate 0.15-0.80 Disolvan 0.03-0.05 Water 92.52-90.15 Hydraulic fracturing fluid (prototype) Technical lignosulfonates modified with hexamethylenetetramine and carbamide 40.98-43.31 - 5.1 / 5.7 0.5 - 21.0 Potassium chloride 3.70-4.32 Aluminum sulphate 0.52-1.03 Formation water 54.80-48.66

table 2 Assessment of the influence of hydraulic fracturing fluid permeability on the filtration characteristics of rocks Field, well Liquids Permeability, K, 1 · 10 ^-3 μm ² Porosity,% Residual water saturation,% Kerosene permeability
K, 1 · 10 ^-3 μm ² Permeability recovery coefficient,% to experience after experience Yamburgskoye, well 413 claimed 73.1 19.1 33.5 31.8 23,2 73.1 Yamburgskoye, well 413 prototype 28,2 14,4 35,4 18.9 4.6 37.5

Claims (1)

Fluid for hydraulic fracturing, including potassium chloride, aluminum sulfate and water, characterized in that the fluid additionally contains sulfacellum grade 800, the surfactant is disolvan in the following ratio, wt.%: potassium chloride 6.00-7.00 sulfacell brand 800 1.30-2.00 aluminum sulfate 0.15-0.80 disolvan 0.03-0.05 water 92.52-90.15