RU2804068C1 - Hydrogel drilling fluid - Google Patents

Abstract

FIELD: construction of oil and gas wells.

SUBSTANCE: invention relates namely to drilling fluids that are suitable both for drilling a transport trunk represented by terrigenous rocks, and for opening productive formations of directional and horizontal wells with ultra-long waste. The drilling mud contains, wt.%: bentonite clay 1.00-2.00; filtration regulator STARFLOK 2.00-3.00; lubricant additive - LUBRICANT BL 2.00-3.00; for peptization of bentonite clay - sodium hydroxide 0.10-0.30; clay modifying additive REGVIZ 0.07-0.15; clay-modifying additive REAGENT "NV" grade K 0.15-0.25; as a carbonate weighting agent - multi-fraction marble ground to 29.00; to prevent swelling and shedding of clay-containing rocks - sodium chloride 0.00-20.00; water the rest.

EFFECT: preservation of holding capacity when drilling inclined and horizontal shafts, efficient removal of cuttings from the well, and expansion of the arsenal of tools.

1 cl, 2 tbl, 2 ex

Description

The invention relates to the construction of oil and gas wells, namely to drilling fluids that are suitable both for drilling a transport trunk represented by terrigenous rocks, and for opening productive formations of directional and horizontal wells with ultra-long waste.

A clay-free drilling fluid is known, which is used to penetrate productive formations of horizontal wells and directional wells with a vertical distance of more than 1000 m, containing wt.%:

biopolymer ASG-1 or Ritizan-M 0.30-0.80 modified starch 1.00-2.50 organic inhibitor additive FC-2000 Plus M 8.00-12.00

potassium chloride 1.50-3.00 marble chips 1.50-3.00

Water rest

The disadvantage of this solution is that clay-free solutions are expensive due to the presence of biopolymers (RF patent No. 2318855, IPC C09K 8/08, op. 03/10/2008).

The closest analogue to the claimed invention, which we take as a prototype, is a low-clay drilling fluid used for drilling productive formations and geophysical studies of oil and gas wells, which contains, wt.%:

bentonite clay 2.00-3.00 carboxymethylcellulose 0.10-0.15 starch 1.00-2.00 regulation reagent electrical resistivity propylene pentamers 1.00-5.00 carbonate weighting material 5.00-8.00 Lubriol W lubricant additive 0.10-0.50 water rest

The disadvantages of this solution are the increased clay content, which significantly reduces the quality of opening the productive formation, as well as the absence of a clay swelling inhibitor in the composition, which limits its use when drilling wells in the occurrence of clay-containing rocks (clays, mudstones, shales, siltstones), prone to swelling, scree and collapse (RF patent No. 2327726, IPC C09K 8/24, op. 06.27.2008).

The technical problem solved by the present invention is to reduce the cost of drilling fluid in the absence of expensive biopolymers through the use of inexpensive domestically produced reagents, thanks to which the holding capacity is maintained when drilling inclined and horizontal shafts and effective removal of cuttings from the well is carried out. Namely, the creation of a clayey drilling fluid with a low content of clay phase and maintaining the necessary filtration and structural-rheological properties.

This technical problem is solved by the fact that a drilling fluid containing bentonite clay, a filtration regulator, a carbonate weighting agent, a lubricant additive and water, according to the invention, contains the STARFLOK reagent as a filtration regulator, ground marble of different fractions as a carbonate weighting agent, and ground marble as a lubricant additive - LUBRIKANT BL, for peptization of bentonite clay - sodium hydroxide, clay-modifying additives REGVIZ and REAGENT "NV" brand K, to prevent premature enzymatic destruction of the reagent STARFLOK - a bactericide and to prevent swelling and crumbling of clay-containing rocks may contain sodium chloride in the following ratio of components, wt .%:

Bentonite clay 1.00-2.00 Filtration regulator STARFLOK 2.00-3.00 Lubricant additive LUBRICANT BL 2.00-3.00 Sodium hydroxide 0.10-0.30 Bactericide 0.03-0.05 Clay modifying additive REGVIZ 0.07-0.15 Clay-modifying additive REAGENT “NV” grade K 0.15-0.25 Multi-fraction ground marble until 29.00 Sodium chloride 0.00-20.00 Water rest

The solution to the stated technical problem of the invention is achieved thanks to the following. Sodium hydroxide promotes additional peptization of bentonite clay, resulting in an increase in the content of colloidal particles. When adding additives based on polyvalent metal salts REGVIZ and REAGENT NV brand K, bentonite particles are modified, resulting in the formation of oligomeric and polymer particles that contribute to the creation of a gel due to a combination of coordination and crystallization-coagulation structuring mechanisms. These modifying additives make it possible to create a solution with such a minimum content of bentonite clay without losing the necessary filtration and structural-rheological properties. Thanks to this structuring mechanism, the system has increased values of dynamic shear stress (DSS), viscosity at low shear rates (LSRS) and a rapidly forming structure at a low concentration of the clay phase. The bactericide prevents premature enzymatic destruction of the STARFLOK reagent. To prevent swelling and crumbling of clay-containing rocks (clays, mudstones, shales, siltstones), NaCl is introduced into the drilling fluid, but there is no coagulating effect on the modified bentonite clay.

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

Example #1

Add 1 g of sodium hydroxide to 855.5 g of tap water while stirring on a laboratory stirrer. After complete dissolution of the reagent, 10 g of bentonite clay is added and dispersed for 15 minutes on a high-speed mixer (11,000 rpm). Without stopping stirring, at intervals of 15 minutes, sequentially introduce 1.5 g of the REGVIZ modifying additive, 1.5 g of the “NV” REAGENT, grade K, 30.0 g of the STARFLOK reagent together with 0.5 g of the bactericide, 80.0 g of marble ground and 20.0 g of lubricant additive LUBRICANT BL. After adding all components, the solution is stirred for 10 minutes on a high-speed mixer and 10 minutes on a laboratory stirrer.

Example No. 2

Add 1 g of sodium hydroxide to 811.5 g of tap water while stirring on a laboratory stirrer. After the reagent is completely dissolved, 15 g of bentonite clay is added and dispersed for 15 minutes on a high-speed mixer (11,000 rpm). Without stopping stirring, with an interval of 15 minutes, 0.7 g of the REGVIZ modifying additive, 1.5 g of the “NV” REAGENT grade K, 20.0 g of the STARFLOK reagent together with 0.3 g of bactericide, 80.0 g of marble are sequentially introduced ground, 50.0 g of sodium chloride and 20.0 g of lubricant additive LUBRICANT BL. After adding all components, the solution is stirred for 10 minutes on a high-speed mixer (11,000 rpm) and 10 minutes on a laboratory stirrer.

Other compositions of the HYDROGEL drilling fluid and the prototype with different ratios of ingredients are prepared in a similar way.

Table 1 shows data on the component compositions of the proposed and known (prototype) drilling fluids.

Determination of the technological parameters of the proposed drilling fluid "HYDROGEL" and the prototype was carried out after keeping the prepared solution at a temperature of 25°C for 16 hours.

Table 1 - Compositions of the HYDROGEL drilling fluid and the prototype

Component name Compositions of drilling fluids, wt.% Claimed Prototype No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 7 No. 8 No. 9 Process water 85.55 81.15 76.75 72.6 80.05 68.75 50.69 43.69 81.85 Bentonite clay 1.0 1.5 1.5 2.0 1.5 2.0 1.7 1.7 2.5 Carboxymethylcellulose -- -- -- -- -- -- -- 0.15 STARFLOCK 3.0 2.0 2.0 2.0 3.0 2.0 3.0 3.0 2.0 Propylene pentamers -- -- -- -- -- -- -- -- 5.0 Lubricant additive "Lubricant BL" 2.0 2.0 3.0 2.0 2.0 3.0 2.0 2.0 0.5 Sodium chloride -- 5.0 -- 5.0 5.0 7.5 13.0 20.0 -- Sodium hydroxide 0.1 0.1 0.3 0.15 0.1 0.3 0.3 0.3 -- Bactericide 0.05 0.03 0.05 0.03 0.05 0.05 0.05 0.05 -- Clay modifying additive REGVIZ 0.15 0.07 0.15 0.07 0.15 0.15 0.07 0.07 -- Clay-modifying additive REAGENT “NV” grade K 0.15 0.15 0.25 0.15 0.15 0.25 0.19 0.19 -- Ground marble (multi-fraction) 8.0 8.0 16.0 16.0 8.0 16.0 29.0 29.0 8.0

Technological parameters of drilling fluids were determined in accordance with GOST 33213-2014 (ISO 10414-1:2008):

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

– plastic viscosity (PV, mPa∙s) was determined on an OFITE rotational viscometer at 49°C;

– dynamic shear stress (DSS, lb/100ft ² ) was determined on an OFITE rotational viscometer at 49°C;

– static shear stress for 10 s and 10 min of rest (SNS10/10, lb/100ft ² ) was determined on an OFITE rotational viscometer at 49°C;

– pH was determined with a pH meter;

– viscosity at low shear rates (VNSS, mPa∙s) was determined on a Brookfield rotational viscometer.

The increase in the height of a clay sample, %, in a drilling fluid environment for 72 hours at a temperature of 50°C was assessed using the OFITE Dinamic Linear Swellmeter.

Table 2 shows the technological indicators of the HYDROGEL drilling fluid and the prototype.

Table 2 - technological indicators of the HYDROGEL drilling fluid and the prototype

Options Solutions according to table 1 Drilling fluid "HYDROGEL" Prototype No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 7 No. 8 No. 9 after aging at 25°C for 16 hours Rheology measurement temperature, °C 49 49 49 49 49 49 49 49 49 PV, mPa∙s 17 8 19 13 8 15 14 17 9.2 DNS,
lb/100 ft ² 27 17 31 22 19 25 thirty 33 6.8 SNS _10/10 ,
lb/100 ft ² 10/13 7/9 12/14 11/14 9/10 12/14 13/16 15/17 2.4/13.9 PF, cm ³ /30min 4.5 4.2 4.9 3.8 3.2 3.1 3.2 3.6 2.3 pH 10.23 9.11 10.15 9.30 9.0 10.2 10.0 10.1 9.7 VNSS, mPa s 38200 24600 41000 35400 27500 39000 74100 40000 13100 Increase in clay sample height, % 31.3 25.1 32.8 24.8 21.4 21.2 18.5 15.3 33.3

The obtained data on technological indicators show that the inventive drilling fluid “HYDROGEL” has the necessary filtration properties (filtration rate less than 5 cm ³ /30 min) and a sufficient increase in the height of the clay sample, which ensures the stability of the well walls. Due to the presence of unique modifying additives in the composition, the inventive drilling fluid has high values of DNS and VNSS with a minimum amount of clay and reduced values of plastic viscosity, due to which hole cleaning in inclined and horizontal sections is improved; The solution also has a rapidly forming structure, which indicates its high-quality holding capacity. With all this, the composition of the solution is financially accessible in the absence of expensive biopolymers.

Claims (2)

A drilling fluid containing bentonite clay, a filtration regulator, a carbonate weighting agent, a lubricant additive and water, characterized in that it contains the STARFLOK reagent as a filtration regulator, ground marble of different fractions as a carbonate weighting agent, LUBRIKANT BL as a lubricating additive, clay-modifying additives REGVIZ and REAGENT "NV" brand K, for peptization of bentonite clay - sodium hydroxide, to prevent premature enzymatic destruction of the reagent STARFLOK - a bactericide and to prevent swelling and crumbling of clay-containing rocks may contain sodium chloride in the following ratio of components, wt.%: Bentonite clay 1.00-2.00 Filtration regulator STARFLOK 2.00-3.00 Lubricant additive LUBRICANT BL 2.00-3.00 Sodium hydroxide 0.10-0.30 Bactericide 0.03-0.05 Clay modifying additive REGVIZ 0.07-0.15 Clay modifying additive REAGENT "NV" grade K 0.15-0.25 Multi-fraction ground marble until 29.00 Sodium chloride 0.00-20.00 Water rest