RU2804720C1 - Biopolymer drilling fluid - Google Patents

Abstract

FIELD: drilling fluids.

SUBSTANCE: water-based biopolymer drilling fluids used for primary opening of formations, as well as for drilling directional intervals and horizontal sections of oil and gas wells. Biopolymer drilling fluid for the initial opening of formations contains, wt.%: xanthan type “ХС ОНК” biopolymer 0.41-0.45; Reatrol modified starch 1.0-1.5; potassium chloride 8-9; soda ash 0.05-0.18; caustic soda 0.05-0.9; hydrophobic carbonate colmatant D20 5.5-6.5; Lubroil lubricant additive 1.2-3; Penta-480V defoamer 0.03-0.06; bactericide 0.05-0.1; water the rest.

EFFECT: increase in the factor of recovery of the initial permeability of the formation up to 35.6-37.1%.

1 cl, 3 tbl, 4 ex

Description

The invention relates to water-based biopolymer drilling fluids and can be used for the initial opening of productive formations, as well as when drilling directional intervals and horizontal sections of oil and gas wells.

A biopolymer drilling fluid is known [RU 2289603 C1, IPC C09K 8/10 (2006.01), publ.: 12/20/2006], containing a xanthan-type biopolymer, a surfactant and a lubricant additive - ethylene diamides of fatty acids - a condensation product of ethylenediamine and phosphatide concentrate, polymer filtration reducer - polyanionic cellulose, or carboxymethylcellulose, or carboxymethyloxy-ethylcellulose, or hydroxyethylcellulose, or hydrolyzed polyacrylonitrile and additionally - alkali metal humates - carbon-alkali reagent UShR or humate-potassium reagent GKR and salts of alkali and/or alkaline earth metals - KCl, NaCl, CaCl2, MgCl2, bischofite and water at the following ratio of components, wt.%:

specified filtration reducer 0.1-1.0 xanthan type biopolymer 0.2-0.5 indicated fatty acid ethylene diamides 0.05-3.0 UShR or GKR 3.0-6.0 specified salts 3.0-40.0 water rest

This biopolymer drilling fluid provides insufficient efficiency of the initial opening of the productive formation,because has high filtration properties. This contributes to excessive penetration of the dispersion medium of this solution into the productive formation with the formation of a water blockade in the bottomhole zone of the formation, which significantly reduces the true potential of the well.

A biopolymer drilling fluid is known [RU 2561630 C2, IPC C09K 8/10 (2006.01), publ.: 08/27/2015], containing polyanionic cellulose, a xanthan-type biopolymer, as a lubricant additive - a product of fatty acids of triglycerides with the number of carbon atoms from 14 to 24, salts of alkali and/or alkaline earth metals KCl, NaCl, CaCl ₂ , MgCl ₂ , bischofite, inhibitor reagent glycoil, multi-fraction weighting agent - barium sulfate, sodium hydroxide, water in the following ratio of components, wt.%:

polyanionic cellulose low degree of viscosity (degree of substitution 0.9, dynamic viscosity <100 mPa s - according to the Brookfield method) 0.2-1.5 polyanionic cellulose high degree of viscosity (degree of substitution 0.9, dynamic viscosity >1000 mPa s - according to the Brookfield method) 0.2-1.5 xanthan type biopolymer 0.1-0.6 lubricant additive 0.07-3.5 salts of alkali and/or alkaline earth metals KCl, NaCl, CaCl2, MgCl2, bischofite 3.0-40.0 sodium hydroxide 0.1-0.6 inhibitor reagent glycoil 0.5-1.0 bactericide 0.01-0.2 multi-fraction weighting agent - barium sulfate up to 80 water rest

The xanthan-type biopolymer can be any xanthan-based polysaccharide. Contains reagent glycoil PG-40 as an inhibitor.

The disadvantage of this composition is the combined use of polyanionic cellulose and xanthan biopolymer, which results in unsatisfactory structural and rheological properties of the drilling fluid. The multicomponent nature complicates the method of preparing this drilling fluid, increases the time spent on preparation, as well as on additional processing during the drilling process to maintain the required parameters.

A known biopolymer drilling fluid [RU 2186819 C1, IPC C09K 7/02 (2000.01), publ.: 08/10/2002] for opening productive formations of horizontal wells and wells with a large deviation angle, containing a biopolymer, polyanionic cellulose, alkali metal hydroxide, lubricant additive - surfactant MIG, modified starch, water-soluble silicic acid salt and water in the following ratio of ingredients, wt.%:

biopolymer 0.05-0.2 modified starch 1.15-2.0 polyanionic cellulose 0.1-0.25 alkali metal hydroxide 0.045-0.16 water-soluble silicic acid salt 0.23-1.2 surfactant MIG surfactant 0.3-1.0 water rest

in this case, the mass ratio of alkali metal hydroxide and water-soluble silicic acid salt is 1:2.5-15.0, respectively.

The specified drilling fluid may additionally contain a weighting agent, taken in the amount necessary to obtain a drilling fluid of calculated density, and selected from the group of the following substances: inorganic salts - sodium, calcium, potassium chlorides, or carbonate weighting agent, or bentonite.

The disadvantage of this solution is the presence in its composition of biodegradable polyanionic cellulose, which can irreversibly reduce the permeability of reservoir rocks.

Famous biopolymer drilling fluid [RU 2711222 C1, IPCC09K 8/10 (2006.01), publ.: 01/15/2020], selected as a prototype, containing components in the following ratio, wt.%:

xanthan gum BIOPOL 0.15-0.25 modified starch MULTISTAR 0.75-1.25 polyanionic cellulose ANIPOL NV 0.12-0.20 sodium hydroxide 0.04-0.40 water-soluble silicic acid salt 0.37-0.60 lubricant additive BL-SALT 0.95-1.55 potassium chloride 4.00-6.00 carbonate weighting material 1.50-3.20 heat-stabilizing additive 0.55-0.90 soda ash 0.05-0.10 bactericide 0.05-0.10 sulfonated bitumen SULFOBIT 0.07-1.10 defoamer Penta-480V 0.05-0.10 organic inhibitory additive BIO XX 0.70-1.10 polyglycols with temperature cloudiness 70-130°С with mineralization 100-150 g/l, 1.35-2.20 barite weighting material up to 45.0 water rest

A significant disadvantage of the prototype is the excessive clogging capacity of the reservoir pore space during the initial opening of the productive formation, as a result of which the permeability recovery coefficient decreases. This effect is determined by the use of heat-resistant polyglycols and a high content of acid-insoluble barite weighting agent. The use of sulfonated bitumen enhances the colmatation effects. Due to its hydrophobic nature, this reagent should provide high recovery rates for oil permeability during well development. However, in practice this effect is absent. In addition, the multicomponent nature of this biopolymer drilling fluid complicates the preparation of the solution and makes it difficult to quickly regulate its technological properties.

The technical result of the proposed invention is the creation of a biopolymer drilling fluid that provides an increase in the recovery rate of the initial permeability of the productive formation.

The proposed biopolymer drilling rig, as in the prototype, contains a xanthan-type biopolymer, modified starch, potassium chloride, soda ash, caustic soda, lubricant additive, antifoam Penta-480B, bactericide and water.

According to the invention, the biopolymer drilling fluid additionally contains a hydrophobic carbonate bridging agent D20, as a biopolymer it contains a biopolymer of xanthan type XC ONK, as a modified starch - modified Reatrol starch, and as a lubricant additive - Lubroil lubricant additive in the following ratio of components, wt. %:

xanthan type biopolymer XC ONK 0.41-0.45 Reatrol modified starch 1.0-1.5 potassium chloride 8-9 soda ash 0.05-0.18 caustic soda 0.05-0.9 hydrophobic carbonate sealant D20 5.5-6.5 Lubroil lubricant additive 1.2-3 defoamer Penta-480V 0.03-0.06 bactericide 0.05-0.1 water rest

The use of caustic and soda ash ensures the pH of the water at a level of 8.5-10.5, due to which the xanthan type biopolymer XC ONK is more effectively dispersed in the dispersion medium of the drilling fluid.

Modified starch Reatol, as a biodegradable component, is designed to reduce the filtration rate of drilling fluid.

Xanthan-type biopolymer XC ONK is a water-soluble powder polysaccharide obtained as a result of the vital activity of Xanthomonas bacteria and is intended to provide the necessary structural and rheological properties of the drilling fluid.

Potassium chloride is intended to regulate the density of the drilling fluid and give it inhibitory properties to reduce the swelling of formation clays.

The introduction of the antifoam Penta-480V prevents foaming and thereby ensures the stability of the technological characteristics of the drilling fluid.

The introduction of the lubricant additive Lubroil, which is resistant to foaming, improves structural, rheological, filtration and lubrication properties, and increases corrosion resistance. At the same time, the active components of the lubricant additive (surfactant) help reduce the surface tension at the boundary of the drilling fluid filtrate - reservoir oil and contribute to high-quality initial penetration.

The bactericide provides suppression of sulfate-reducing bacteria, solubility in water eliminates oil contamination and ensures effective disinfection of adhesive forms of bacteria in stagnant zones.

The introduction of hydrophobic carbonate plugging agent D20 into the drilling fluid formulation ensures the creation of a thin filter cake, low-permeable to the water phase, on the well walls, limiting the penetration of the drilling fluid filtrate deep into the productive formation. At the same time, during well development, the resulting filter cake has an increased value of phase permeability for oil, which makes it possible to obtain high permeability recovery coefficients

Under the influence of a pressure drop, a filtration cake is formed on the well wall, which does not allow the aqueous phase of the drilling fluid filtrate to pass through during the initial opening of the productive formation. During well development, the hydrophobic shell of the D20 carbonate plug is dissolved by the formation oil, thereby increasing the distance between the solid particles of the hydrophobic carbonate plug in the filter cake. As dissolution proceeds, the hydraulic resistance to formation fluids decreases, the phase permeability of the cake to oil increases, thereby increasing the value of the initial penetration recovery coefficient. The result is a simplification of the development technology, a reduction in the cost and time of processing the bottomhole formation zone and an increase in the quality of the initial opening of productive formations through the use of accessible and non-scarce materials.

The proposed biopolymer drilling fluid ensures an increase in the recovery rate of the initial permeability of the productive formation to 35.6-37.1%.

The use of the proposed drilling fluid reduces clogging of the bottom-hole zone of the well with the solid phase of the drilling fluid, due to the use of hydrophobic carbonate plug D20, which is partially soluble for hydrocarbons in the drilling fluid, which leads to an increase in well productivity.

The composition and concentration of the components of the biopolymer drilling fluid provide the necessary structural and rheological properties for drilling directional and horizontal sections of wells.

Table 1 shows the compositions of drilling fluids.

Table 2 shows the general technological parameters of the drilling fluids of the invention and the prototype.

Table 3 shows the recovery coefficient values of the invention and prototype.

The essence of the proposed invention is illustrated by the following examples of preparing drilling fluid in laboratory conditions .

Example 1. To obtain 500 g of the claimed drilling fluid, 0.25 g of caustic soda and 0.25 g of soda ash, 40 g of potassium chloride are added to 416 g of tap water while stirring on an overhead laboratory mixer. After the reagents are completely dissolved, 2.05 g of xanthan type biopolymer XC ONK is introduced and stirring continues for another 30 minutes. After 30 minutes, 5 g of modified Reatrol starch is added to the resulting solution with stirring and stirred for 20 minutes. After complete dissolution of the polymer agents on a high-speed mixer (11,000 rpm), 30 g of hydrophobic carbonate sealant D20, 6 g of Lubroil lubricant additive together with 0.15 g of Penta-480B defoamer and 0.25 g of bactericide are sequentially introduced at intervals of 1 minute. After adding all components, the solution is stirred for 3 minutes on a high-speed mixer.

As a result, a drilling fluid was obtained with the following content of components, wt.%: xanthan type biopolymer XC ONK 0.41; modified starch Reatrol 1; clay inhibitor based on potassium chloride 8; soda ash 0.05; caustic soda 0.05; hydrophobic carbonate bridging agent D20 6; lubricant additive Lubroil 1.2; defoamer Penta-480V 0.03; bactericide 0.05; water 83.2 (Table 1, sample No. 1).

Example 2. To obtain 500 g of the claimed drilling fluid, 0.35 g of caustic soda and 0.45 g of soda ash, 42.5 g of potassium chloride are added to 412 g of tap water while stirring on an overhead laboratory mixer. After the reagents are completely dissolved, 2.1 g of xanthan type biopolymer XC ONK is introduced and stirring continues for another 30 minutes. After 30 minutes, 6 g of modified Reatrol starch is added to the resulting solution with stirring and stirred for 20 minutes. After complete dissolution of the polymer agents on a high-speed mixer (11,000 rpm), 27.5 g of hydrophobic carbonate bridging agent D20, 9 g of Lubroil lubricant additive together with 0.2 g of Penta-480B defoamer and 0.35 g are sequentially introduced at intervals of 1 min. bactericide. After adding all components, the solution is stirred for 3 minutes on a high-speed mixer.

As a result, a drilling fluid was obtained with the following content of components, wt.%: xanthan type biopolymer XC ONK 0.42; modified starch Reatrol 1.20; clay inhibitor based on potassium chloride 8.50; soda ash 0.07; caustic soda 0.09; hydrophobic carbonate bridging agent D20 5.50; lubricant additive Lubroil 1.80; defoamer Penta - 480V 0.04; bactericide 0.07; water 82.30 (Table 1, sample No. 2).

Example 3. To obtain 500 g of the claimed drilling fluid, 0.4 g of caustic soda and 0.6 g of soda ash, 45 g of potassium chloride are added to 405 g of tap water while stirring on an overhead laboratory mixer. After the reagents are completely dissolved, 2.15 g of xanthan type biopolymer XC ONK is introduced and stirring continues for another 30 minutes. After 30 minutes, 6.75 g of modified Reatrol starch is added to the resulting solution with stirring and stirred for 20 minutes. After the polymer agents are completely dissolved on a high-speed mixer (11,000 rpm), 27.5 g of hydrophobic carbonate bridging agent D20, 11.5 g of the Lubroil lubricant additive together with 0.3 g of the antifoam Penta - 480B and 0 are sequentially introduced at intervals of 1 min. 4 g bactericide. After adding all components, the solution is stirred for 3 minutes on a high-speed mixer.

As a result, a drilling fluid was obtained with the following content of components, wt.%: xanthan type biopolymer XC ONK 0.43; modified starch Reatrol 1.35; clay inhibitor based on potassium chloride 9; soda ash 0.12; caustic soda 0.08; hydrophobic carbonate bridging agent D20 5.5; lubricant additive Lubroil 2.3; defoamer Penta - 480V 0.06; bactericide 0.08; water 81.1 (Table 1, sample No. 3).

Example 4. To obtain 500 g of the claimed drilling fluid, 0.45 g of caustic soda and 0.9 g of soda ash, 45 g of potassium chloride are added to 396 g of tap water while stirring on an overhead laboratory mixer. After the reagents are completely dissolved, 2.25 g of xanthan type biopolymer XC ONK is introduced and stirring continues for another 30 minutes. After 30 minutes, 7.5 g of modified Reatrol starch is added to the resulting solution with stirring and stirred for 20 minutes. After the polymer agents are completely dissolved on a high-speed mixer (11,000 rpm), 32.5 g of hydrophobic carbonate bridging agent D20, 15 g of Lubroil lubricant additive together with 0.3 g of Penta-480B defoamer and 0.5 g are sequentially introduced at intervals of 1 min. bactericide. After adding all components, the solution is stirred for 3 minutes on a high-speed mixer.

As a result, a drilling fluid was obtained with the following content of components, wt.%: xanthan type biopolymer XC ONK 0.45; modified starch Reatrol 1.5; clay inhibitor based on potassium chloride 9; soda ash 0.18; caustic soda 0.09; hydrophobic carbonate bridging agent D20 6.5; Lubroil 3 lubricant additive; defoamer Penta - 480V 0.06; bactericide 0.1; water 79.1 (Table 1, sample No. 4).

Table 1 shows data on the component compositions of drilling fluids according to the invention and the prototype (samples No. 5 and No. 6).

The main parameters of drilling fluids, according to the invention and the prototype, were determined in accordance with GOST 33213-2015 at room and reservoir temperatures:

- density (ρ, g/cm ³ ) was determined using OFITE lever scales;

- filtration index (PF, cm ³ /30 min) was determined at a pressure drop of 0.7 MPa on the OFITE filter press;

- high-temperature filtration index (HTPF, cm ³ /30 min) was determined at 90°C and a pressure drop of 0.7 MPa on the OFITE HTHP filter press;

- plastic viscosity (PV, mPa⋅s) was determined on an OFITE rotational viscometer at 25 and 90°C;

- dynamic shear stress (DSS, dPa) was determined on an OFITE rotational viscometer at 25 and 90°C;

- static shear stress for 10 s and 10 min of rest (SNS 10 s/10 min, dPa) was determined on an OFITE rotational viscometer at 25 and 90°C;

- the pH value was determined with a pH meter;

- the inhibitory ability was assessed on the OFITE Dinamic Linear Swellmeter device as an increase in the height of the compressed sample from the disintegrated core (%) exposed to the drilling fluid for 24 hours at 90°C;

- interfacial tension at the phase boundary between the formation oil and the drilling fluid filtrate was determined using a KRUSS GmbH tensiometer.

The data in Table 2 shows that the proposed biopolymer drilling fluid and the prototype have stable filtration, structural-rheological and inhibitory properties both at room and elevated temperatures. However, the stability of the properties of the invention is achieved with a much smaller amount of chemical reagents, which is an undeniable advantage over the prototype.

The prototype is characterized by low values of interfacial tension at reservoir temperature, which is a consequence of low recovery coefficients. Filtration tests on core were carried out under thermobaric conditions simulating reservoir conditions of exposure in time and parameters similar to the process of initial opening in a UIPC-type filtration installation. The test results show that the claimed drilling fluid has high values of the coefficient of recovery of the initial permeability of the productive formation compared to the prototype (Table 3).

Claims (2)

Biopolymer drilling fluid for the initial opening of productive formations, containing a xanthan-type biopolymer, modified starch, potassium chloride, soda ash, caustic soda, carbonate bridging agent, lubricant additive, defoamer, bactericide and water, characterized in that it contains xanthan gum CS as a xanthan-type biopolymer ONK contains the hydrophobic carbonate bridging agent D20 as a carbonate bridging agent, modified Reatrol starch as a modified starch, Penta-480V defoaming agent as a defoaming agent, and Lubroil lubricating additive as a lubricating additive in the following ratio of components, wt.%: xanthan gum HS ONK 0.41-0.45 Reatrol modified starch 1.0-1.5 potassium chloride 8-9 soda ash 0.05-0.18 caustic soda 0.05-0.9 hydrophobic carbonate sealant D20 5.5-6.5 lubricant additive Lubroil 1.2-3 defoamer Penta-480V 0.03-0.06 bactericide 0.05-0.1 water rest