RU2486224C2 - Light salt mud - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to oil and gas industry, particularly drilling mud used when drilling through salt-bearing and terrigenous-carbonate deposits of exploratory and producing wells in abnormally low formation pressure conditions. The salt mud contains, wt %: drilling mud powder 4-6, stabiliser - salt-resistant carboxymethyl cellulose 0.3-1, modified starch 0.8-1.2, sodium chloride 1-20, potassium chloride 3-7, alkali 0.01-0.02, lignosulphonate reagent 1-2, silicate microspheres 4.5-6, water - the balance.

EFFECT: low density.

5 ex, 2 tbl

Description

The invention relates to the oil and gas industry, in particular to drilling fluids used in drilling strata of saline, terrigenous-carbonate sediments of prospecting and exploratory and production wells, as well as for opening productive formations under conditions of abnormally low reservoir pressure (ANP).

Known drilling fluid containing bentonite, stabilizer - carboxymethyl cellulose CMC, hydrolyzed polyacrylonitrile "uniflock", xanthan biopolymer, water repellent, aluminosilicate microspheres, water. In another embodiment, instead of CMC, the solution contains carboxymethylated starch as a stabilizer.

A disadvantage of the known drilling fluids is the instability of the drilling fluid to salt aggression.

The closest technical solution is a drilling fluid containing salt-resistant clay, potassium chloride, barium hydroxide, starch, condensed sulphite alcohol bard - KSSB, hydroxyethyl cellulose - OEC and water. Increasing the strength and water resistance of clayey rocks, including saline intersalt moistened clays, preventing complications due to talus, landslides, flow of plastic clayey rocks, narrowing the well when drilling wells, is decided by the fact that the drilling fluid additionally contains barium hydroxide.

However, the known technical solution does not contribute to a decrease in the density of the drilling fluid, therefore, excludes the possibility of its use in ANPD. The introduction of inorganic salts, which are inhibitors of clay swelling and fluidity of salts, on the contrary leads to an increase in the density of the drilling fluid.

The proposed technical solution makes it easy to control the technological parameters and reduce the density of the mineralized drilling fluid.

This object is achieved in that a lightweight mineralized drilling fluid containing clay powder, a stabilizer — salt-resistant carboxymethyl cellulose, modified starch, mineral salt — sodium chloride, alkali, lignosulfonate reagent and water; additionally contains potassium chloride and silicate material to reduce the density of the drilling fluid — silicate microspheres in the following ratio of ingredients, wt.%: clay powder - 4-6; salt-resistant carboxymethyl cellulose - 0.3-1; modified starch - 0.8-1.2; mineral salt - sodium chloride NaCl - 1-20 and a hydration inhibitor - potassium chloride KCl - 3-7; alkali - 0.01-0.02; lignosulfonate reagent - 1.5-2; silicate microspheres - 4.5-6; water is the rest.

The claimed solution is prepared in the following order: the clay powder is shut with fresh water and mixed until completely dispersed. Then, a stabilizer reagent, salt-resistant carboxymethyl cellulose, is introduced into the clay suspension and mixed again, then modified starch is mixed, KCl is introduced, mixed, then NaCl, lignosulfonate reagent and alkali are added. All reagents are administered dry. They lighten the microspheres to the desired density, mix again, and the drilling fluid is considered ready.

Example 1. Prepare a clay suspension of 4 wt.%, Mix until the clay is fully dispersed. The stabilizer reagent CMC-TC 1 wt.%, MK-F 1.2 wt.% Are introduced into the resulting clay suspension. After thorough mixing, KCl 5 wt.% And NaCl 20 wt.% Are added. KSSB-2M 1.5 wt.% And NaOH 0.02 wt.% Are introduced into the salt-saturated solution. Then 5 wt.% Microspheres are introduced. After stirring for 30 minutes, the solution is considered ready.

Example 2. Prepare a clay suspension of 4 wt.%, Mix until the clay is fully dispersed. The stabilizer reagent KMTs-TS 0.3 wt.%, KMK-Bur1 0.8 wt.% Are introduced into the resulting clay suspension. After thorough mixing, KCl 5 wt.% And NaCl 20 wt.% Are added. KSSB-2M 2 wt.% And NaOH 0.02 wt.% Are added to the saline solution. Then 5 wt.% Microspheres are introduced. After stirring for 30 minutes, the solution is considered ready.

Example 3. Prepare a clay suspension of 5 wt.%, Mix until the clay is fully dispersed. In the resulting clay suspension, the stabilizer KMTs-TS is introduced - 1 wt.%, MK-F - 1.2 wt.%. After thorough mixing, KCl 5 wt.% And NaCl 20 wt.% Are added. In the saline solution, FHLS-M 1 wt.% And NaOH 0.02 wt.% Are added. Then 5 wt.% Microspheres are introduced. After stirring for 30 minutes, the solution is considered ready.

Example 4. Prepare a clay suspension of 5 wt.%, Mix until the clay is fully dispersed. The stabilizer reagent CMC-TS 0.5 wt.%, MK-F - 1 wt.% Are introduced into the resulting clay suspension. After thorough mixing, KCl 5 wt.% And NaCl 20 wt.% Are added. KSSB-2M 2 wt.% And NaOH 0.02 wt.% Are added to the saline solution. Then 4.9 wt.% Microspheres are introduced. After stirring for 30 minutes, the solution is considered ready.

Example 5. Prepare a clay suspension of 6 wt.%, Mix until the clay is fully dispersed. The stabilizer reagent CMC-TS 0.3 wt.%, MK-F - 0.8 wt.% Are introduced into the resulting clay suspension. After thorough mixing, KCl 5 wt.% And NaCl 20 wt.% Are added. KSSB-2M 2 wt.% And NaOH 0.02 wt.% Are added to the saline solution. Then enter 4.7 wt.% Microspheres. After stirring for 30 minutes, the solution is considered ready.

The composition and properties of these solutions are shown in table No. 1,2.

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

As the stabilizer of the drilling fluid, salt-resistant carboxymethyl cellulose with various degrees of polymerization is used, for example, KMTs-TS (TU 2231-034-97457491-2010). The reagent is a fine-grained white powder, readily soluble in water. Ecologically harmless, non-toxic. The use of CMC-TS less than 0.3 wt.% Leads to an increase in water loss, a decrease in the viscosity and stability of the solution. Increasing the value of more than 1 wt.% Leads to a significant increase in viscosity.

To reduce filtration, modified starch is used, for example, KMK-Bur, MK-F (TU 2262-016-32957739, TU 9187-002-00343094-2005), etc. Using modified starch less than 0.8 wt.% Leads to an increase in water loss . Increasing the value of more than 1.2 wt.% Leads to a significant increase in viscosity.

Clay powder (TU 2164-41219638-2005), as well as other GOST and TU are used as a structuring agent. Clay powder was used in the range of 4-6 wt.%. A decrease in the content of clay powder of less than 4 wt.% Leads to zero values of the SNA. An increase in the percentage of clay powder increases the viscosity of the solution, which leads to an increase in the crust, sticking, poor penetration.

Technical salt sodium chloride is produced according to TU 2152-067-002-09527-98 and others.

The potassium chloride hydration inhibitor is a fine crystalline white powder with ρ-1.98 g / cm ³ , in accordance with GOST 4568-95, TU 2152-018-00203944-95, etc.

The introduction of NaCl up to 20 wt.% And KCl from 3 to 5 wt.% When drilling the thickness of saline, as well as terrigenous-carbonate deposits will prevent the destruction of the wellbore. An increase in total mineralization above 25 wt.% Will lead to the precipitation of salt into the solution.

To maintain the pH of the drilling fluid, alkali is used - sodium hydroxide and (or) potassium hydroxide. Optimum concentrations of alkali metal hydroxides are in the range of 0.01-0.02 wt.%. A decrease or increase in alkali results in a decrease or increase in the pH of the solution, respectively.

As a regulator of rheological properties, a lignosulfonate reagent is used, for example, condensed sulfite-alcohol stillage for mineralized solutions KSSB-2M (TU 2454-325-05133190-2000), which is a condensation product of technical lignosulfonates in an acidic medium. In appearance, KSSB-2M is a brown powder. The solubility in water is not less than 90%, the amount of decrease in filtration is not less than 50%, the hydrogen index is 7-9. Adding KSSB-2M more than 2 wt.% Leads to foaming of the drilling fluid. Putting KSSB-2M below 1 wt.% Inefficiently reduces water loss and SNA. It is also possible to use FHLS and analogues of foreign manufacturers.

To reduce the density of the drilling fluid, silicate microspheres having a true density of 0.32-0.6 g / cm ³ , bulk density of 0.19-0.43 g / cm ³ , compressive strength 136-1224 atm, and stability up to 600 ° C, for example, HGS5000. HGS5000 microspheres are made from sodium borosilicate glass, which makes them chemically resistant, insoluble in water and hydrocarbons, and environmentally friendly. It is also possible to use other silicate microspheres with similar properties.

The input of silicate microspheres of 4.5-6 wt.% Provides the optimal density of the drilling fluid.

The use of the proposed lightweight mineralized drilling fluid in difficult geological conditions, for example, when drilling the thickness of saline sediments in the conditions of the API, allows you to adjust the density of the drilling fluid.

Table 1 Composition of Lightweight Mineralized Mud Composition number Component composition, wt.% Clay KMTS TS MK-F KMK-Bur1 NaOH KSSB-2M FHLS-M Kcl NaCl Microsphere HGS5000 Water one 3 1,2 1,2 - 0.02 2 - 5 twenty 5 61.58 2 four one 1,2 - 0.02 1,5 - 5 twenty 5 60.29 3 four 0.3 - 0.8 0.02 2 - 5 twenty 5 59.89 four 5 one 1,2 - 0.02 - one 5 twenty 5.5 57.78 5 4,5 one 1,2 - 0.02 2 - 5 twenty 4.9 56.38 6 5 0.7 1,2 - 0.02 - one 5 twenty 4,5 55.38 7 6 0.3 0.8 - 0.02 2 - 5 twenty 4.7 54.18 8 6.5 0.3 0.8 - 0.02 2 - 5 twenty 4,5 52.68 9 5 0.3 1,2 - 0.02 2 - 5 twenty 5 52,48 10 5 0.2 1,2 - 0.02 2 - 5 twenty 6 51.58 eleven 5 1,2 1,2 - 0.02 2 - 5 twenty 5 49.58 12 5 0.5 one - 0.02 2 - 5 twenty 4.9 49.98 13 5 0.5 1,5 - 0.02 2 - 5 twenty 6 47.98 fourteen 5 0.5 0.8 - 0.02 2 - 5 twenty 5 47.68 fifteen 5 0.5 one - 0.02 0.5 - 5 twenty 5 47.98 16 5 0.5 one - 0.02 1,5 - 5 twenty 5 45.98 17 5 0.5 one - 0.02 2,5 - 5 twenty 5 43.98 eighteen four 0.3 0.8 - 0.02 2 - 5 one 6 63.38

table 2 Parameters of Lightweight Highly Mineralized Mud Structure Density, g / cm ³ Conditional viscosity, s The rate of filtration, cm ³ SNA, dPa pH in 1 min in 10 min one 1.06 26 6.5 0 eleven 9 2 1.06 31 5 27 42 9 3 1.06 36 4.3 35 47 9 four 1.06 thirty 4,5 34 45 9 5 1.06 34 5 32 49 9 6 1.06 39 3 35 65 9 7 1.06 45 four 47 76 9 8 1.06 fifty four 53 82 9 9 1.06 29th 4,5 22 38 9 10 1.06 23 6 17 29th 9 eleven 1.06 72 3 51 79 9 12 1.06 36 8.5 33 62 9 13 1.06 55 2,5 38 69 9 fourteen 1.06 38 5 34 63 9 fifteen 1.06 47 8 fifty 73 9 16 1.06 43 5 41 69 9 17 1.06 31 2,5 23 49 9 eighteen 0.92 43 5 thirty 44 9

Claims (1)

Mineralized drilling fluid containing clay powder, salt-resistant carboxymethyl cellulose, modified starch, alkali, sodium chloride NaCL, lignosulfonate reagent and water, characterized in that it additionally contains silicate material to reduce the density of the drilling fluid - silicate microspheres and a hydration inhibitor with the following potassium chloride KCL with ingredients, wt.%:
Clay powder 4-6 Stabilizer - salt resistant carboxymethyl cellulose 0.3-1 Modified Starch 0.8-1.2 Sodium Chloride NaCL 1-20 Potassium Chloride KCL 3-7 Alkali 0.01-0.02 Lignosulfonate Reagent 1-2 Silicate Microspheres 4,5-6 Water Rest