RU2593154C1 - Sand-carrying fluid for implementation of slot hydraulic sand jet perforation - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil and gas industry. Sand-carrying fluid for implementation of slot hydraulic sand jet perforation contains, wt. %: xanthan gum 0.2-0.25; soda ash 0.1-0.2; sodium formate 5-20; surfactant HP-1 of K brand 0.1-0.25; water is rest.

EFFECT: technical result is reducing filtrate return, reduction of plastic and conventional viscosities.

1 cl, 1 tbl, 3 ex

Description

The invention relates to the oil and gas industry and can be used with slotted sandblasting perforation.

The sand carrier fluid should be formulated to provide minimal filtration and a viscosity that would make it possible to hold the sand in suspension and preserve the filtration-capacitive properties of the reservoir. The high holding capacity of the sand carrier fluid should prevent the possibility of sand settling along the path of the sand carrier to the bottom.

The closest composition of the same purpose to the claimed invention in terms of features is a sand-carrier fluid for hydraulic fracturing, which can be used during hydro sandblasting perforation, including PBMA bentonite clay powder, carboxymethyl cellulose, GKZh-10 silicone fluid, celloton-F, aluminum sulfate and water in the following ratio of components, wt. %:

PBMA Bentonite Clay Powder 3.00-5.00 Carboxymethyl cellulose 0.60-1.50 Silicone fluid GKZH-10 0.50-1.00 Cellon-f 1.00-1.10 Aluminum sulphate 0.15-0.80 Water Rest

(RF patent No. 2483094 dated 05/27/2013). This composition is taken as a prototype.

The features of the prototype, which coincides with the features of the claimed invention, are water, a structurant and a filtration reducer, a surfactant.

The disadvantages of the known composition adopted for the prototype are high plastic and conditional viscosities and filtrate recovery, due to the fact that the known liquid contains a solid phase - PBMA bentonite clay powder and a high concentration of polymers such as celloton-F and carboxymethyl cellulose. In addition, bentonite clay powder is a hard-to-remove colmatant, which reduces the natural permeability of the formation.

The objective of the invention is the creation of a sand-based water-based fluid for implementing sandblasting perforation with low filtrate recovery, reduced plastic and conditional viscosities using biodegradable polymers.

The problem was solved due to the fact that the well-known sand carrier for the implementation of slit hydro-sandblasting perforation containing a structure former and a filter reducing agent, a surfactant and water, according to the invention, contains xanthan gum as a surface forming agent and a filter reducing agent, as a surfactant - GF-1 grade K and additionally contains sodium formate and soda ash in the following ratio of ingredients, wt. %:

Xanthan gum 0.2-0.25 Soda ash 0.1-0.2 Formate Na 5-20 GF-1 brand K 0.1-0.25 Water Rest

Distinctive features of the proposed solution from the solution of the prototype - as a structure-forming agent and a filter reducing agent, contains xanthan gum; contains GF-1 grade K as a surfactant; the introduction of sodium formate and soda ash; different quantitative ratio of the used ingredients wt. %: xanthan gum - 0.2-0.25; soda ash - 0.1-0.2; formate Na - 5-20; GF-1 grade K - 0.1-0.25; water is the rest.

The achievement of the specified technical result is achieved through the use of xanthan gum as a structure-forming agent and a filter reducing agent. Xanthan molecules adsorb water with the formation of a three-dimensional network of xanthan double helix, similar in structure to the gel, but differing in lower viscosity, which allows to reduce filtration into the reservoir and to provide high solution endurance. The branched spatial structure of the xanthan polymer chain provides a reduction in the filtration of fluid into the reservoir. Xanthan forms toxitropic, thick non-Newtonian solutions. Its solutions exhibit the following properties: high viscosity at low concentration and shear rate; resistance to the influence of enzymes, salts, acids, bases; resistance to changes in ionic strength, temperature; constant high viscosity in a wide pH range from 2 to 12; high modulus of elasticity.

Xanthan gum is a natural biopolymer, decomposes due to biodegradation in the reservoir and does not lead to its clogging. Its high pseudo-plasticity (with an increase in shear force, the viscosity sharply decreases, after removing the force, the initial viscosity is restored almost instantly) helps to reduce the plastic and conditional viscosity of the proposed sand carrier fluid.

The introduction of sodium formate into the composition of the sand-carrier fluid can significantly reduce the hydration of clay minerals, and therefore, preserve the filtration-capacitive parameters of productive reservoirs.

The use of the water-repellent agent GF-1 of brand K in the claimed composition prevents the formation of water-oil emulsions and water films on the rock, which will provide a high recovery rate of the permeability of the formation rocks and reduce the corrosion of oilfield equipment.

The introduction of soda ash into the composition makes it possible to reduce the hardness of water and create an alkaline environment, which will provide fast hydration and a high rate of polymer “dissolution”.

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

- Xanthan gum - a natural polysaccharide biopolymer.

- Soda ash - is a white crystalline powder.

- Sodium formate (sodium formate) according to TU 2432-011-00203803-98 - crystalline powder of white or gray color without impurities.

- GF-1 grade K according to TU 2482-054-53501222-2006 - a liquid from colorless to light brown in color, is a surfactant solution.

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

Example 1

1.85 g of xanthan gum (0.22%) was gradually added to 750 g of water (89.38%). Then, 1.68 g of soda ash (0.2%) was added; 83.91 g of Na formate (10%); 1.68 g of GF-1 grade K (0.2%) was mixed.

Example 2

In 750 g of water (94.4%), 1.99 g of xanthan gum (0.25%) was gradually added. Then, 0.79 g of soda ash (0.1%) was added; 39.72 g of Na formate (5.0%); 1.99 g of HF-1 grade K (0.25%) was mixed.

Example 3

1.89 g of xanthan gum (0.2%) was gradually added to 750 g of water (79.45%). Then, 1.89 g of soda ash (0.2%) was added; 188.8 g of Na formate (20.0%); 1.42 g of GF-1 grade K (0.15%) was mixed.

In the process of testing the obtained liquids, the values of their properties were determined - plastic viscosity, dynamic shear stress, conditional viscosity, filtration and density. Measurement of the main technological parameters of the sand carrier was carried out using standard instruments.

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

As can be seen from the table, the claimed liquid has several advantages:

- lower plastic viscosity;

- reduced conditional viscosity;

- reduced filtration into the reservoir.

Thus, due to the improvement of technological parameters, the efficiency of the inventive liquid is increased during hydro sandblasting.

The developed fluid is explosion and fireproof, non-toxic, environmentally friendly. The composition of the sand carrier fluid ensures minimal contamination of the reservoir, which positively affects its permeability.

Claims (1)

Sand-carrier fluid for implementing slotted hydro-sandblasting perforation containing a structure-forming agent and a filtration reducer, a surfactant and water, characterized in that it contains xanthan gum as a structure-forming agent and a filtration reducer, and grade KF-1 as a surfactant additionally contains sodium formate and soda ash in the following ratio of ingredients, wt. %:
Xanthan gum 0.2-0.25 Soda ash 0.1-0.2 Formate Na 5-20 GF-1 brand K 0.1-0.25 Water Rest