METHOD OF DRILLING OF WELLS COMPLICATED BY ABSORBING HORIZONS Russian patent published in 2015 - IPC E21B21/14 C09K8/38 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to drilling of oil and gas wells, namely to methods of prevention and elimination of absorption of drilling mud during well construction. The method of drilling of wells complicated by absorbing horizons includes circulation of fresh or mineralized water based drilling muds in a wellbore, injection of the additive containing high-colloid clay and cellulose ester, and the subsequent generation of aphrons by means of adding to drilling mud of aphron-forming surfactant. As an additive use in number of not less than 1.2 wt % of the mass of drilling mud the aphron-stabilizing complex providing ten-second static shear stress of the formed drilling mud, at least 25.5 dPa, and containing the named cellulose ester, an the alkaline additive Sintal BT - a product of modification of fatty acids by potassium alkali and nonionic surfactant, and high-colloid clay - palygorskit dry mud, at their following mass ratio as (1÷2):(1÷2):(7.5÷20) respectively. The aphron-stabilizing surfactant is used for the surfactant fresh drilling mud based on esters of fatty acids of vegetable oils, or sodium alpha olefin sulphate, or protein frother, and for the mineralized drilling mud - oxyethylated monoalkyl phenols or oxi-ethylated higher fatty alcohols amounting 0.05-0.6 wt % of the drilling mud weight.

EFFECT: improvement of efficiency of the method of drilling of the wells complicated by absorbing horizons at simultaneous decrease of material and time costs and providing a continuity of process.

4 cl, 3 tbl, 2 ex