METHOD FOR DISASTROUS DRILLING MUD LOSS ZONES ISOLATION DURING OIL AND GAS HOLE DRILLING Russian patent published in 2006 - IPC E21B33/13 

FIELD: oil and gas well drilling, particularly methods or devices for cementing, for plugging holes, crevices, or the like.

SUBSTANCE: method involves determining interval of mud loss formation to be isolated; lowering drilling string up to loss zone reaching; injecting hardening plugging mix of grouting mortar with fibrous filler into the well with the use of cementing unit, wherein the fibrous filler is supplied into grouting mortar during injection operation via funnel installed at upper end of drilling string. Before carrier mortar preparation connection pipe attached to mixer receptacle of cement mixing machine and adapted to supply pressurized mixing water with the use of jet pump of cementing unit is substituted for connection pipe having lesser diameter, namely 8-9 mm diameter. The connection pipe with lesser diameter provides carrier mortar preparation and injection into well at rate of 7-8 m³ per hour, wherein the carrier mortar is based on cement, bentonite cement or mud solution. The filler, namely cord fiber or cotton waste is supplied in amount of 25-50 kg per 1 m³ of the carrier mortar. After plugging mortar feeding termination the funnel is separated from the drilling string and replaced for sealing head. The plugging mortar is forced under pressure in the loss formation.

EFFECT: increased isolation efficiency, reduced time and decreased material consumption.