RU2700132C1 - Weighted drilling fluid - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil and gas industry, in particular to water-based drilling fluids used in drilling in complex geological conditions, for example, drilling of exploratory and production wells in conditions of abnormally high pressures AHPR. Weighted drilling fluid contains, wt%: structure-forming agent – clay 3–6; reagent high molecular weight sodium-carboxymethyl cellulose stabilizer KMC-1100 0.3–0.8; potassium chloride KCl 3–7; potassium hydroxide KOH 0.2–0.3; lignosulphonate reagent – condensed sulphite-spirit syrup CSSS-2M 2–2.5; ferrochrome lignosulphonate FCLS-M 1–2.5; antifoaming agent Santi F 0.2–0.3; lubricating additive DSB-4TTP 1.5–2.0; barite weighting agent KB-3 30–50; water-soluble salt filler – sodium or potassium formate 12–15; ferriferous filler – haematite or iron-ore concentrate of FOC 10–25; water – balance.

EFFECT: improving drilling efficiency under conditions AHPR, improved quality of drilling mud of high density by reducing filtration, improving rheological and sedimentation properties.

1 cl, 2 tbl, 4 ex

Description

The invention relates to the oil and gas industry, in particular to water-based drilling fluids used when drilling in difficult geological conditions, for example, when drilling exploratory and production wells under conditions of abnormally high reservoir pressure, where mining and geological conditions require the use of high density drilling fluids ( up to 2500 kg / m ³ ).

The known composition of the drilling fluid containing flask, carboxymethyl cellulose KMC-900, calcium chloride, flotation reagent T-80, potassium hydroxide, lubricant additive SMAD, uniflock, KSSB-2M, barite and water [1].

A disadvantage of the known drilling fluid is the high loss due to the content of Ca ²⁺ , low values of lubricating properties and stability of the drilling fluid; high shear shear coefficient, which leads to the need for significant efforts to move the drill pipe, complications in the form of puffs and sticks, as well as insufficient density of the drilling fluid - not more than 1870 kg / m ³ .

Also known is a drilling fluid containing clay, a stabilizer reagent KMTS-900, a mineral salt - KCl, a flocculant, a lubricant additive DSB-4TTP, KSSB-2M, potassium hydroxide, barite and water [2].

However, the known technical solution does not contribute to the achievement of the required density of the drilling fluid, while maintaining the structural-mechanical and filtration properties of the drilling fluid at an optimal level.

Closest to the proposed technical solution is a drilling fluid containing sodium formate; xanthan type polysaccharide "StabVisco-F"; modified starch "MK-3"; GKZh-11 hydrophobizing liquid; Lubricant Extra-S; weighting additive - galena weighting agent and water [3].

The disadvantages of this drilling fluid is that due to the lack of a mineral structure-forming agent (clay, etc.), the optimization of the structural and rheological properties of the drilling fluid is achieved by the use of special additives, namely polysaccharide-type polymers. In this case, the weighting agent may precipitate during high-temperature or salt destruction of the polymer and, as a result, complications and emergency situations occur at the well. It is also inevitable to constantly maintain a sufficiently high concentration of polymers in the composition of the drilling fluid, which entails an increase in the cost of the drilling fluid.

In addition, galena (lead sulfide), a scarce and expensive material, used as a weighting additive. Harmful effects on the human body and lack of application experience inhibits its use for drilling operations.

The proposed solution improves the quality of the drilling fluid by improving the structural, mechanical and filtration properties and increasing the stability of the drilling fluid when it is weighted to a density of 2500 kg / m ³ .

The technical result of the invention is to increase drilling efficiency under conditions of abnormally high reservoir pressures, to improve the quality of the drilling fluid at high densities by improving the rheological and filtration properties, as well as stabilizing other parameters of the drilling fluid.

The technical result is achieved by the fact that a weighted drilling fluid containing a structuring agent — clay, mineral salt — potassium chloride KCl, a pH regulator — potassium hydroxide KOH, a lignosulfonate reagent — condensed sulphite-distillery vinasse KSSB-2M, a barite weighting agent KB-3, a lubricant additive ДСБ-4ТТП, antifoam Santi F and water, characterized in that the additional weighting of the drilling fluid is made by the complex input of dry (glandular - hematite or LFA) and water-soluble salt (sodium or potassium formate) weighting agents, and to stabilize the filtration and rheological properties, it additionally contains a stabilizing reagent - high molecular weight sodium-carboxymethyl cellulose KMTs-1100 and ferrochrome lignosulfonate FHLS-M in the following ratio of ingredients, wt. %:

Clay - bentonite clay powder according to TU 2164-41219638-2005, structure-forming agent.

Reagent stabilizer high molecular weight sodium-carboxymethyl cellulose KMC-1100 according to TU-2231-066-50664923-2005 - powdery material from white to cream color, is used as a stabilizer for drilling mud. The degree of polymerization is 1100, the degree of substitution is 90, and the solubility in water is 99.5%.

Potassium hydroxide KOH according to GOST 9285-78, is used as a regulator of alkalinity of the drilling fluid.

Condensed sulfite-alcohol stillage lignosulfate reagent KSSB-2M according to TU 2458-343-05133190-2012 is a powder of dark brown color, it is a product of the condensation of pulp and paper waste. Solubility in water of at least 90%, density 1.39 g / cm ³ , pH 7-9. Used to reduce fluid loss and reduce the viscosity of the solution.

Ferrochrome lignosulfonate FHLS-M according to TU 2458-344-05133190-2012 is a light brown powder and is a product of the processing of sulphite alcohol distillery stillage (PRS). It is well soluble in water, has a pH of 4-5. It is used as a reducer of the rheological properties of drilling fluids.

Antifoam Santi F according to TU 2257-022-18947160-2004.

The lubricant additive DSB-4TTP according to TU 2415-004-00151807-2006 is a dark brown liquid, based on monoethanolamine salt of tall oil and polyglycol, with a pour point of -45-48 ° С. Environmentally friendly.

Mineral salt - potassium chloride KCl according to GOST 4568-95 - small crystals of grayish-white color or small grains of various shades of red-brown color.

According to GOST 4682-84, the KB-3 barite weighting agent is supplied in the form of a concentrate with a BaSO ₄ content _of at least 90.0 wt. %, humidity not more than 2.0%, density not less than 4210 kg / m ³ .

The water-soluble salt weighting agent sodium or potassium formate according to TU 2432-011-00203803-98 is a free-flowing white powder, it is a sodium or potassium salt of formic acid and is a waste in the production of pentaerythritol.

Glandular weighting agent - hematite according to GOST 26475-85 - iron oxide, powder from iron-black to steel-gray, with a density of 4600 kg / m ³ or LRA according to TU 0708-029-00158754-97 - the weight of the weighting agent is 4600-5000 kg / m ³ , iron ore concentrate corresponds to the highest grades of weighting agents according to the standard of API and OSMA, provides weighting of drilling fluids due to its high dispersion and ensures sedimentation stability (stability) of fluids.

When preparing the inventive solution, the following order is used: the clay is closed in fresh water and mixed until completely dispersed. Then, the stabilizer reagent high molecular weight sodium carboxymethyl cellulose KMC-1100 is introduced into the clay suspension and mixed again, then the lignosulfonate reagent condensed sulfite-alcohol vinasse KSSB-2M, potassium hydroxide KOH, ferrochromium lignosulfonate Fhas additive FHAS is added sequentially in dry form. DSB-4TTP, mineral salt potassium chloride KCl. Then they are weighed with a KB-3 grade barite weighting agent, mixed, then additionally weighted with a water-soluble salt weighting agent, sodium or potassium formate and a glandular weighting agent (hematite or LFA).

Here are examples of the preparation of the inventive drilling fluid in laboratory conditions.

Example 1. Prepare a 3% clay suspension, mix until the clay is fully dispersed. 0.8% of CMC-1100 stabilizing reagent-stabilizer is introduced into the resulting clay suspension and mixed again. KSSB-2M - 2.5%, KOH - 0.2%, FHLS-M - 1.0%, antifoam Santi F - 0.2%, DSB-4TPP - 1.5% after mix thoroughly with 3% KCl. After stirring for 30 minutes, 30% of a barite weighting agent of the KB-3 grade and then 12% of sodium (or potassium) formate, 10% of a glandular weighting agent (hematite or LFA) are introduced. After thorough mixing, the solution is considered ready.

Example 2. Prepare a 4.0% clay suspension, mix until complete dispersion of the clay. 0.6% of CMC-1100 stabilizer reagent is introduced into the resulting clay suspension and mixed again. KSSB-2M - 2.3%, KOH - 0.2%, FHLS-M - 1.3%, antifoam Santi F - 0.2%, DSB-4TPP - 1.5% after mix thoroughly with 4% KCl. After stirring for 30 minutes, 30% of a barite weighting agent of the KB-3 grade and then 15% of sodium (or potassium) formate, 25% of a glandular weighting agent (hematite or LFA) are introduced. After thorough mixing, the solution is considered ready.

Example 3. Prepare a 5.0% clay suspension, mix until complete dispersion of the clay. 0.5% of CMC-1100 stabilizer reagent is introduced into the resulting clay suspension and mixed again. KSSB-2M - 2.2%, KOH - 0.3%, FHLS-M - 2.0%, antifoam Santi F - 0.3%, DSB-4TPP - 1.8% after mix thoroughly with 7% KCl. After stirring for 30 minutes, 40% of barite weighting agent of the KB-3 grade and then 13% of sodium formate (or potassium), 13% of glandular weighting agent (hematite or LFA) are introduced. After thorough mixing, the solution is considered ready.

Example 4. Prepare a 6.0% clay suspension, mix until the clay is fully dispersed. 0.3% of the CMC-1100 stabilizer reagent is introduced into the resulting clay suspension and mixed again. KSSB-2M - 2.0%, KOH - 0.3%, FHLS-M - 2.5%, antifoam Santi F - 0.3%, DSB-4TPP - 2.0% after mix thoroughly with 3% KCl. After stirring for 30 minutes, 50% of a barite weighting agent of the KB-3 grade and then 12% of sodium (or potassium) formate, 12% of a glandular weighting agent (hematite or LFA) are introduced. After thorough mixing, the solution is considered ready.

In accordance with the above examples, various versions of the solution are prepared, characterized by the quantitative content of the ingredients.

Bentonite clays in the range of 3-6% are used in said drilling fluid. A decrease in clay content of less than 3% subsequently leads to the loss of a dry weighting agent (barite or glandular). An increase in the percentage of clay of more than 6% leads to a deterioration in the structural and mechanical properties, the impossibility of pumping, an increase in the thickness of the filter cake, sticking, and a decrease in the rate of penetration.

As a stabilizing agent for the drilling fluid, high molecular weight sodium carboxymethyl cellulose KMTs-1100 is used. The use of CMC-1100 of less than 0.3% does not lead to a decrease in water loss and stabilization of the solution. An increase in the content of CMC-1100 of more than 0.8% leads to a significant increase in viscosity, while filtration does not decrease.

As a mineral salt that increases the inhibitory ability of the solution, potassium chloride KCl is used. A study of the interaction of clay rocks with solutions of potassium salts shows that the swelling process accelerates with increasing concentration in a solution of potassium chloride and ends in 2-4 hours at a 5-7% concentration of potassium chloride. Within this concentration, the degree of clay swelling also reaches its minimum values. A further increase in the concentration of potassium chloride does not lead to noticeable changes in the rates of swelling, and a decrease in the concentration of KCl of less than 3% does not lead to inhibition of the drilling fluid.

As a mineral salt that increases the density of the drilling fluid, sodium or potassium formate is used. Within the concentration range of 12-15%, the optimum value of the density of the drilling fluid is achieved, in combination with other dry weighting agents, with stable structural, mechanical and filtration indices. In addition, this component has an inhibitory effect. An increase in the concentration of sodium or potassium formate over 15% leads to an increase in structural and mechanical properties and filtration. A decrease in concentration of less than 12% does not lead to a significant increase in the density of the drilling fluid (in combination with other weighting agents), nor does it shorten the period of clay swelling.

The optimal value of potassium hydroxide KOH is in the range from 0.2-0.3%. A decrease or increase in KOH leads, respectively, to a decrease or increase in the pH of the solution, which negatively affects the performance of polymer reagents in the composition of the drilling fluid. With a decrease in pH of less than 7, the polymer reagents do not completely dissolve and the ability to lower viscosity and decrease the filtration of drilling fluids in lignosulfonate reagents decreases. The use of reagents at pH values above 10 leads to an increase in the consumption of lignosulfonate reagents, and the characteristics of polymers as thickeners and filter reducing agents deteriorate.

As a lubricant additive based on monoethanolamine salt of taly oil and polyglycol, DSB-4TTP is used. In this additive, expensive substances, residual products of the production of synthetic rubber T-66, T-80, tal oil, are replaced by polyglycol (polyhydric alcohols). Its optimal concentration in the composition of the drilling fluid is 1.5-2.0%. A decrease in the concentration of the lubricant additive of less than 1.5% in the solution does not lead to an improvement in the lubricity, as a result of which sticking and tightening of the drilling tool occur. An increase in the lubricant additive of more than 2.0% leads to an unreasonable increase in costs, with constant indicators of lubricating properties.

To regulate rheological parameters, lignosulfonate reagent FHLS-M is introduced in the range of 1.0-2.5%. Reagent injection of less than 1.0% does not have an effective effect on plasticization (liquefaction) of the drilling fluid. The use of concentrations of more than 2.5% reduces the structural and mechanical properties of the drilling fluid and creates the risk of weight loss, and the filtration does not improve.

Also, to control the filtration, KSSB-2M is introduced into the solution, the effectiveness of which is especially increased in solutions with a high degree of mineralization. As shown by experimental data, the optimal additives for its use are in the range of 2-2.5%. The use of a concentration of less than 2% does not have the necessary effect on the filtration and rheological parameters of the drilling fluid. Concentrations of more than 2.5% impair the structural and mechanical properties of the drilling fluid.

The introduction of lignosulfonate reagents into the solution promotes its foaming, therefore, Santi F antifoam is additionally introduced into the solution at an optimal concentration of 0.2-0.3%.

The use of the proposed weighted drilling fluid in difficult geological conditions, for example, when drilling deep and superdeep wells with abnormally high reservoir pressures, allows the drilling fluid density to be increased to 2500 kg / m ³ , ensuring stability in terms of rheology, filtration and cost parameters.

Information sources:

1. RF patent No. 2410405 of December 25, 2009, published in Bulletin No. 3, January 27, 2011, according to Cl. C09K 8/20;

2. RF patent No. 2235751 of 02/07/2003, publ. to the bulletin No. 25, 09/10/2004, according to class C09K 7/02;

3. RF patent No. 2665276 of March 29, 2017, publ. Bulletin No. 15, 05.24.2018, according to class C09K 8/20.

Claims (4)

A weighted drilling fluid containing a builder — clay, mineral salt — potassium chloride KCl, a pH adjuster — potassium hydroxide KOH, a lignosulfonate reagent — condensed sulphite-distillery stillage KSSB-2M, barite weighting agent KB-3, lubricant additive DSB-4TTPBi, antifoam F and water, characterized in that the additional weight of the drilling fluid is made by the complex input of dry (glandular - hematite or iron ore concentrate LFA) and water-soluble salt (sodium formate or potassium formate) weighting agents, and for stabilization of filtration and rheological properties additionally contains a stabilizer reagent - high molecular weight sodium-carboxymethyl cellulose KMTs-1100 and ferrochrome lignosulfonate FHLS-M in the following ratio of ingredients, wt.%: Clay 3-6 High molecular weight stabilizer reagent sodium carboxymethyl cellulose KMTs-1100 0.3-0.8 Mineral salt potassium chloride KCl 3-7 DSB-4TTPB lubricant additive 1.5-2.0 Potassium Hydroxide KOH 0.2-0.3 Condensed lignosulfonate reagent sulphite-alcohol barda KSSB-2M 2-2.5 Barite weighting agent KB-3 30-50 Ferrochromlignosulfonate FHLS-M 1-2,5 Antifoam Santi F 0.2-0.3 Water Soluble Salt Weighting Agent sodium or potassium formate 12-15 Glandular Weighting Agent - Hematite or ZhRK 10-25 Water Rest