TECHNOLOGY TO ELIMINATE ABSORBING OF DRILLING SOLUTION WHEN DRILLING WITHIN THE RANGE OF TRAPPEAN INTRUSIONS

The purpose of the study is to develop a technology and technical means for the elimination of drilling mud losses of various intensity in faulted and cavernous rocks in the sinking zones of a drilling tool and open fractures while ensuring complete and efficient cut-off of water horizon intervals as well as borehole wall consolidation against weakening. The study uses the methods of the analysis of mining and geological conditions of oil and gas well drilling on the territory of Nepa-Botuoba anteclise featuring the drilling mud absorption of various intensity and drops of reservoir and bottomhole pressures, as well as a comparative estimation of the insulation quality of drilling mud loss zones, of time and material consumption for their elimination, prevention of ramble, caving, drilling tool sticking resulting from its jamming by the fragments of fractured rocks. As a result the technologies used at the SredneBotuoba gas-condensate field when performing plugging operations have been studied. The efficiency of various methods and techniques, in the presence of intervals of fractured and unstable rocks in the wells has been estimated. Their advantages and disadvantages have been analyzed. On the basis of all these, the authors have developed an alternative method to control drilling mud losses of any intensity under the excessive pressure on the zone of fractured rocks. The method involves influencing the absorption channels by the polymers that solidify upon the contact with the formation water and significant increase in the volume of the mineralized mixture. This allows the mixture to penetrate into the absorption channels due to the polymer volume expansion and increase of borehole wall stability. Hydroactive polyurethane foam is proposed as a polymer. An immersion pod has been developed that allows the polymer to be delivered directly to the absorption zone. The developed method of delivering the grouting mixture directly to the absorption zone and the use of expandable polymers made it possible to increase the cyclic drilling rate, reduce the consumption of grouting materials, improve the culture and environmental friendliness of production during insulation works as well as shorten the time of well construction.

drilling, drilling mud loss control, polyurethane, immersion pod

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