METHOD OF PREPARING REAGENT FOR TREATMENT OF DRILLING MUDS Russian patent published in 2000 - IPC

FIELD: oil and gas production. SUBSTANCE: efficient thermostabilizing reagent for optimization of filtration, rheological, and lubrication parameters of clayey drilling muds and for inhibition of swelling of clayey drilling muds and inhibition of swelling of clayey deposits, which consists of mixture of crude lignosulfonates (40-45% calculated for solid materials), sodium and potassium bichromates (5-10%), calcium chloride (2-3%) and water, is prepared by polycondensation of indicated mixture with no heating at pH 4.0-4.5 to achieve viscosity 40-60 Ps after preliminary conversion of lignosulfonates and calcium chloride into their 40-45% aqueous solutions. Reagent is additionally modified with addition of 3-7.5% of tallow acids from forestry enterprises, after which preparation of reagent can be completed by rapid thin-layer drying, preferably for 15-20 sec, on the surface of, partially inserted in reagent solution, rotating hollow drum heated from inside to temperature 80-100 C. It is also possible to complete preparation of reagent by loosening rubber-like material lost its flowability in the final polycondensation phase, drying material at 18-30 C, and powdering it. Reagent represents a high-molecular compound with molecular weight up to 3000, which dissolves in water after short-time swelling step. Reagent is added to drilling mud in quantity 1 to 2.5 vol % and is efficient within temperature range between 10 and 120 C at calcium ion level up to 400 mg/l. Its maximum efficiency manifests 8-12 hr after addition. EFFECT: improved working characteristics. 5 cl, 2 tbl, 5 ex