APPLICATION OF PERMANENT MONITORING PROBES FOR CONTROL OF MIGRATING GASES TO NEAR-SURFACE AND ATMOSPHERE IN THE OIL WELLS AREA.

In the zones of boreholes drilled to explore and extract hydrocarbons uncontrolled migration of gas to soil environment and therefore to atmosphere may occur. Such phenomena may be related to insufficient tightness of the rock mass or poor technical condition of the borehole. Due to the occurrence of potential risks to the environment and human health and life, a set of constant monitoring probes was designed and tested. Location of six permanent monitoring probes were based on the results of surface geochemical surveys carried out in three cycles of measurements in 2014, before the drilling of planned wells. Measured concentrations of methane, total alkanes C2-C5 and total alkenes C2-C4 in all measuring sessions reach up to 11.99, 0.367 and 0.918 ppm, respectively. Conducted periodical studies show an increase in the average value of methane and total alkanes C2-C5 concentrations after drilling and hydraulic fracturing. This may suggest a negligible impact of performed drilling works, the effect of which is microseepage of hydrocarbons from the borehole to the soil. The proposed monitoring procedures of near to borehole zone proved to be justified and should be carried out during drilling of wells related to exploration of oil and gas. [ABSTRACT FROM AUTHOR]