SALT-RESISTANT BENTONITE COMPOSITION FOR PREPARING WATER-BASED DRILLING FLUIDS Russian patent published in 2024 - IPC C09K8/03 C09K8/22 

FIELD: construction of oil and gas wells.

SUBSTANCE: invention relates to structure-forming compositions based on bentonite for preparing flushing fluids. Salt-resistant bentonite composition for preparing water-based drilling fluids contains, wt.%: bentonite clay powder 86.0–98.5; soda ash 0.5–6.0; synthetic polysaccharide 0.5–4.0; xanthan or guar gum 0.5–4.0. Used bentonite clay powder contains not less than 65 wt.% montmorillonite. Synthetic polysaccharide is selected from a group comprising hydroxyethyl cellulose, hydroxypropyl cellulose. First, said bentonite powder with moisture content of not more than 12 wt.% is mixed with soda ash ground to a powder state, mixture is sent for aging at a temperature of at least 5 °C for 24 hours, after which it is mixed with finely dispersed said synthetic polysaccharide, lastly finely dispersed said gum is added.

EFFECT: possibility of preparing stable clay suspensions based on sea, mineralized and salt-saturated water, concentration of sodium chloride in which can vary from 1,000 to 300,000 mg/l.

1 cl, 1 tbl, 6 ex