RU2440399C1 - Drilling fluid for drilling of controlled directional wells (versions) - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: as per the first version the drilling fluid contains the following, wt %: PBMA bentonite 6.0-7.0; sodium carbonate 0.1÷2.0; sodium hydroxide 0.1-0.5; Givpan 0.2-0.3; Kamtsel polyanionic cellulose PATs-VV 0.1-0.3; Lubriol lubricant 1.0; acrylate lignosulphonate reagent ALS 0.2-0.3; antifoaming agent - 10% suspension of polyethylene in solar oil or kerosene PES 0.1-0.2. As per the second version the drilling fluid contains the following, wt %: PBMA bentonite 5.0-6.0; sodium carbonate 0.1÷2.0; sodium hydroxide 0.1-0.5; Givpan 0.2-0.3; Kamtsel polyanionic cellulose PATs-VV 0.1-0.3; Kamtsel polyanionic cellulose PATs-SV 0.1-0.3; Lubriol 1.0; ALS 0.2-0.3; polyethyl siloxane fluid (PSF) 0.1-0.2. As per the third version the drilling fluid contains the following, wt %: PBMA bentonite 2.0; sodium carbonate 0.1÷0.5; sodium hydroxide 0.1÷0.5; Kamtsel polyanionic cellulose PATs-VV 2.0; Kamtsel polyanionic cellulose PATs-SV 2.0; ALS 0.2÷0.3; xanthan gum 0.1.

EFFECT: possibility of failure-free drilling of controlled directional wells in complicated mining and geological conditions.

3 cl, 6 tbl, 3 ex

Description

The invention relates to the drilling of wells, in particular to drilling fluids for drilling directional wells.

Known formulations of solutions have been mainly developed for many years for drilling vertical wells, for example, a drilling fluid containing, wt.%: Bentonite - 1 ÷ 2; stabilizer - carboxymethyl cellulose CMC - 0.6 ÷ 0.8; hydrolyzed polyacrylonitrile "uniflock" - 0.1 ÷ 0.2; xanthan biopolymer - 0.08 ÷ 0.10; water repellent - 0.05 ÷ 0.10; aluminosilicate microspheres - 5 ÷ 20; water - the rest. In another embodiment, instead of CMC, the solution contains 1.0 ÷ 1.4 wt.% Carboxymethylated starch instead of CMC (RU 2309970, 2007).

A disadvantage of the known solution is the impossibility of its use when drilling directional wells. Using this solution can lead to complications when drilling such wells.

Known formulation of the drilling fluid containing, kg / m ³ : bentonite clay - 30 ÷ 72; soda ash - 1 ÷ 2.5; caustic soda - 0.2 ÷ 0.7; CMC of low viscosity - 0 ÷ 3.5; ICLUB - 3 ÷ 8; ICD - 0.5 ÷ 3; IKSTAB or GRINDRIL - 2.6 ÷ 4.5; IKPAN-SL - 2.5 ÷ 4.5; IKPAN-RL - 1.2 ÷ 2.5; water - the rest (RU 2231534, 2004). Although this solution takes into account the possibility of drilling directional wells, due to its rheological properties it cannot guarantee trouble-free drilling of such wells in difficult geological conditions.

Known drilling mud containing, wt.%: Bentonite clay - 2.0 ÷ 3.0; carboxymethyl cellulose - 0.1 ÷ 0.15; starch - 1.0 ÷ 2.0; reagent for regulating electrical resistivity - propylene pentamers - 1.0 ÷ 5.0; carbonate weighting agent - 5.0 ÷ 8.0; Lubriol W lubricant additive - 0.1 ÷ 0.5; water - the rest (RU 2327726, 2006).

A disadvantage of the known drilling fluid is its low viscosity, which can lead to various complications when drilling directional wells and, as a consequence, to accidents.

The technical result of the proposed group of technical solutions, united by a single inventive concept, is the emergence of trouble-free drilling of directional wells in complicated mining and geological conditions.

In the first embodiment, the proposed drilling fluid contains PBMA bentonite (TU 2164-002-00136716-01) - clay powder from bentonite clay, activated by calcined salt; soda ash; caustic soda; Givpan - alkaline hydrolyzed polyacrylonitrile feed; Kamcel PAC-VV - high viscosity polyanionic cellulose; Lubriol is a lubricant additive based on modified fatty acids and oleins; acrylate lignosulfonate reagent (ALS); antifoam - a ten percent suspension of polyethylene in solar oil or kerosene (PES) and water, in the following ratio, wt.%:

PBMA bentonite 6.0 ÷ 7.0 soda ash 0.1 ÷ 2.0 caustic soda 0.1 ÷ 0.5 Givpan 0.2 ÷ 0.3 Camcel PAC-VV 0.1 ÷ 0.3 Lubriol 1,0 ALS 0.2 ÷ 0.3 PES 0.1 ÷ 0.2 water rest

the solution has parameters (table 1).

Table 1 Drilling fluid parameters (option 1) Raft-
nost
g / cm ³ Conditional viscosity, s Plastic viscosity, MPa · s Dynamic shear stress (CSN), dPa Static shear stress (CHC _1/10 ), dPa 1.12 60-100 not regulated not regulated not regulated

In a second embodiment, the proposed drilling fluid contains PBMA bentonite; soda ash; caustic soda; Givpan; Kamcel PAC-VV and Kamcel PAC-SV - medium viscosity polyanionic cellulose; Lubriol; ALS; antifoam - a ten percent suspension of polyethylene in solar oil or kerosene (PES) and water, in the following ratio, wt.%:

PBMA bentonite 5.0 ÷ 6.0 soda ash 0.1 ÷ 2.0 caustic soda 0.1 ÷ 0.5 Givpan 0.2 ÷ 0.3 Camcel PAC-VV 0.1 ÷ 0.3 Camels PATs-SV 0.1 ÷ 0.3 Lubriol 1,0 ALS 0.2 ÷ 0.3 PES 0.1 ÷ 0.2 water rest

while the solution has parameters (table 2).

table 2 Drilling fluid parameters (option 2) Raft-
nost
g / cm ³ Conditional viscosity, s Filtration, cm ^3/30 min Plastic viscosity, MPa · s Dynamic shear stress, dPa Static shear stress (SNA _1/10 ), dPa 1.08-1.12 40-50 <12 <15 50-60 20-40 / 50-100

In the third embodiment, the proposed drilling fluid contains PBMA bentonite, soda ash, caustic soda, Kamcel PAC-BB and Kamcel PAC-SV, ALS, xanthan gum and water, with the following ratio, wt.%:

bentonite 2.0 caustic soda 0.1 ÷ 0.5 soda ash 0.1 ÷ 0.5 Camcel PAC-VV 2.0 Camels PATs-SV 2.0 ALS 0.2 ÷ 0.3 xanthan gum 0.1 water rest

the solution has parameters (table 3).

Table 3 Drilling fluid parameters (option 3) Raft-
nost
g / cm ³ Conditional viscosity, s Filtration, cm ^3/30 min Plastic viscosity, MPa · s Dynamic shear stress, dPa Static shear stress (SNA _1/10 ), dPa 1.06-1.08 30-45 <6 fifteen 70-100 20-40 / 30-60

The method of preparing 1 m ^{3 of} drilling fluid according to the first embodiment (density ρ = 1.12 kg / m ³ ) is as follows. To prepare 1 m ^{3 of} drilling fluid, 60–70 kg of PBMA bentonite is taken and dissolved in water, then 1–20 kg of soda ash and 1–5 kg of caustic soda are added to remove polyvalent ions and adjust the pH, respectively. With vigorous stirring, Kamcel PAC-BB 1 ÷ 3 kg and Givpan are added 2 ÷ 3 kg. In order to prevent foaming, a PES antifoam of 1 ÷ 2 kg is added. Then, to reduce viscosity and filtration, add ALS 2 ÷ 3 kg, at the end of the cooking process add a lubricant additive Lubriol 10 kg.

The method of preparing 1 m ^{3 of} drilling fluid according to the second option (ρ = 1.08 ÷ 1.12 kg / m ³ ) is reduced to the following. To prepare 1 m ^{3 of} drilling fluid, 50–60 kg of PBMA bentonite is taken and dissolved in water, then 1–20 kg of soda ash and 1–5 kg of caustic soda are added to remove polyvalent ions and adjust the pH, respectively. With vigorous stirring, Kamcel PAC-BB 1 ÷ 3 kg, Kamcel PAC-SV 1 ÷ 3 kg and Givpan 2 ÷ 3 kg are added. In order to prevent foaming, a PES antifoam of 1 ÷ 2 kg is added. Then, to reduce viscosity and filtration, add ALS 2 ÷ 3 kg, at the end add a lubricant additive Lubriol 10 kg.

The method of preparing 1 m ^{3 of} drilling fluid according to the third embodiment (ρ = 1.06 ÷ 1.08 kg / m ³ ) can be carried out as follows. To prepare 1 m ^{3 of} drilling fluid, 20 kg of PBMA bentonite is taken and dissolved in water, then 1-5 kg of soda ash and 1-5 kg of caustic soda are added to remove polyvalent ions and adjust the pH, respectively. With vigorous stirring, Kamcel PAC-BB 1 ÷ 3 kg, Kamcel PAC-SV 1 ÷ 3 kg are added. Without stopping mixing, add 1 kg of xanthan gum. Then, to reduce viscosity and filtration, 2–3 kg is added to the ALS solution.

The density of the above drilling fluid options can mainly be adjusted by the amount of PBMA bentonite. To ensure the stability of the walls of the well and create back pressure on them, the density of the solution, as a rule, should not be less than 1.06, but also should not exceed 1.12 g / cm ³ . When using a solution with a density of less than 1.06 g / cm ³ , screeches and collapses can occur, and when using a solution with a density of more than 1.12 g / cm ³ , absorption can occur, therefore, the concentration of PBMA bentonite and other components of the solution should be in specified ranges.

No less important indicators are the viscosity of the drilling fluid and the static shear stress. These two parameters can be adjusted by selecting the concentration of the polymers (Givpan, Kamcel PAC-VV, Kamcel PAC-SV), the higher the viscosity and static shear stress, the greater the concentration of polymers. Insufficient viscosity will lead to a deterioration in the carrying capacity, and excessive viscosity will lead to an increase in the hydraulic resistance in the circulation system and, as a consequence, to the destruction of the wellbore. A low value of the static shear stress will lead to a significant subsidence of the sludge along the wellbore when the circulation ceases, and a high value of it will create large hydraulic resistance at the moment of the resumption of circulation, which can lead to equipment breakdown. From the foregoing, it follows that the concentration of polymers in the proposed options for the drilling fluid should be within strictly specified reduced limits.

The concentration of caustic soda depends on the need to bind Ca ^{2+ ions} , the excessive concentration of which can lead to a deterioration in the properties of the drilling fluid or its coagulation.

Example 1. The drilled rocks are represented by loose, weakly cemented unstable sands, gravel, pebbles, sandy loam, loams, sandstones, clays and mudstones, siltstones, Quaternary and Ordovician deposits. Complications during drilling (passing) of these unstable deposits can be associated with possible scree and collapse of the walls of the well. Mud absorption is likely. To prevent complications, it is recommended to use a drilling fluid (clay) with a high viscosity, which is achieved by treating the solution with Givpan polymer. High viscosity is required to improve the cleaning of wells from sand, gravel and to prevent the possible subsidence of sand in containers.

In this regard, for drilling on these rocks, it is advisable to use the drilling fluid according to option 1, which in this particular case contains the following ingredients, wt.%:

PBMA bentonite 6.5 soda ash 0.3 caustic soda 0.3 Givpan 0.3 Camcel PAC-VV 0.2 Lubriol 1,0 ALS 0.2 PES 0.1 water rest

while the solution has the parameters shown in table 4.

Table 4 Drilling fluid parameters (example 1) Raft-
nost
g / cm ³ Conditional viscosity, s Filtration, cm ^3/30 min Plastic viscosity, MPa · s Dynamic shear stress (CSN), dPa Static shear stress (SNA _1/10 ), dPa 1.10-1.12 80-100 <12 not regulated not regulated not regulated

The presence of Givpan and Kamcel PAC-BB polymers in the solution allows to increase the viscosity of the drilling fluid, thereby reducing its absorption and increasing the carrying capacity, which, ultimately, allows you to reliably fix the walls of the wells. The introduction of additional polymer into the solution allows to reduce the likelihood of accidents when drilling these rocks.

Example 2. When drilling the above rocks and a significant influx of Ca ^{2+ ions} into the solution, as well as the need to adjust the pH, it is possible to use the drilling fluid according to option 2, according to which the solution contains the following components, wt.%:

PBMA bentonite 5.5 soda ash 1,5 caustic soda 0.4 Givpan 0.3 Camcel PAC-VV 0.2 Camels PATs-SV 0.2 Lubriol 1,0 ALS 0.25 PES 0.15 water rest

the solution has the parameters shown in table 5.

Table 5 Drilling fluid parameters (example 2) Raft-
nost
g / cm ³ Conditional viscosity, s Filtration, cm ^3/30 min Plastic viscosity, MPa · s Dynamic shear stress, dPa Static shear stress (CHC _1/10 ), dPa 1.10-1.12 45-50 <12 <15 50-60 20-40 / 50-100

Using a solution of this composition (containing a significant amount of caustic soda) will allow Ca ²⁺ ions to be bound, this will lead to stabilization of the solution and will ensure failure-free drilling of carbonate rocks.

Example 3. Drillable rocks are represented by the alternation of sandstones, siltstones, coal seams. In this case, it is possible to use the drilling fluid according to option 3, in accordance with which the mud contains the following components, wt.%:

PBMA bentonite 2.0 caustic soda 0.2 soda ash 0.2 Camcel PAC-VV 2.0 Camels PATs-SV 2.0 ALS 0.2 xanthan gum 0.1 water rest

while the solution has the parameters shown in table 6.

Table 6 Drilling fluid parameters (example 3) Raft-
nost
g / cm ³ Conditional viscosity, s Filtration, cm ^3/30 min Plastic viscosity, MPa · s Dynamic shear stress, dPa Static shear stress (CHC _1/10 ), dPa 1.07-1.08 35-45 <6 fifteen 70-100 20-40 / 30-60

When drilling this interval, a biopolymer — a high-purity xanthan gum — is introduced into the composition of the drilling fluid. Experience in drilling horizontal and directional wellbores has shown the feasibility of using biopolymer reagents, the solutions of which have high pseudoplastic and thixotropic characteristics. When the circulation is stopped, such solutions form a strong structure that does not allow sludge particles to precipitate, and have a low viscosity at high shear rates, which ensures easy pumping of the solution to the bottom and its additional cleaning. This composition allows for trouble-free drilling of wells with a complex profile.

Claims (3)

1. Drilling fluid for drilling directional wells, containing bentonite, soda ash, caustic soda, Givpan, carboxymethylcellulose, viscosity reducer and stabilizer, lubricant Lubriol, antifoam and water, using PBMAil bentonite as carboxyme bentonite; The PAC-BB camcel, as a viscosity reducer and stabilizer, is ALS acrylate lignosulfonate reagent, and as a defoamer, a 10% suspension of polyethylene in solar oil or kerosene P . C, with the following ratio of ingredients, wt%:
Bentonite PBMA 6.0-7.0 Soda ash 0.1-2.0 Caustic soda 0.1-0.5 Givpan 0.2-0.3 Camcel PAC-VV 0.1-0.3 Lubriol 1,0 ALS 0.2-0.3 PES 0.1-0.2 Water Rest 2. Drilling fluid for directional wells, containing bentonite, soda ash, caustic soda, Givpan, carboxymethyl cellulose, viscosity reducer and stabilizer, lubricant Lubriol, antifoam and water, while PBMA bentonite is used as bentonite, and PBMA bentonite is used as carboxymethyl cellulose PAC-BB and Kamcel PAC-SV, as a viscosity reducer and stabilizer - ALS, and as a defoamer - PES in the following ratio of ingredients, wt.%:
Bentonite PBMA 5.0-6.0 Soda ash 0.1-2.0 Caustic soda 0.1-0.5 Givpan 0.2-0.3 Camcel PAC-VV 0.1-0.3 Camels PATs-SV 0.1-0.3 Lubriol 1,0 ALS 0.2-0.3 PES 0.1-0.2 Water Rest 3. Drilling fluid for directional wells, containing PBMA bentonite, caustic soda, soda ash, carboxymethyl cellulose, viscosity reducer and stabilizer, biopolymer and water, while Kamts PAC-BB and Kamts PAC-SV are used as carboxymethyl cellulose as a reducing agent viscosity and stabilizer - ALS, and as a biopolymer - xanthan gum in the following ratio of ingredients, wt.%:
Bentonite PBMA 2.0 Caustic soda 0.1-0.5 Soda ash 0.1-0.5 Camcel PAC-VV 2.0 Camels PATs-SV 2.0 ALS 0.2-0.3 Xanthan gum 0.1 Water Rest