Determination of areas of gas methane accumulation in carbon-mass massives by transient electromagnetic sounding method (on the example of the San Juan coal basin; USA)

Abstract

According to the results of the research with the method of point electromagnetic sounding (PEMS) of the area of the coal basin of San Juan the criteria were obtained for the allocation of plane anomalies; promising for the extraction of gas from coal seams that are located at a small depth. The source of hydrocarbons is much deeper (depths of 1400—1700 m). The migration of gas and its concentration in the intermediate collector; which is the coal bed and enclosing rock; occurs mainly in vertical zones. The TEMZ method allows localization of the deep source and the vertical zones that undergo gas migration. The said technology can be used in solving the problems of carbonaceous mass degassing together with drilling wells. It is also advisable to use the method before commencing work on the degassing of coal seams and enclosing coal basins. In this case local electromagnetic anomalies (vertical; stratum) are distinguished; the system of tectonic disturbances of the research area is determined. Subsequent drilling of wells establishes the geological nature of these anomalies and determines the ways of the most efficient arrangement of wells for the degassing of carbonaceous arrays. To increase the efficiency of forecasting the distribution of collectors in the coal-bearing array of existing mines; it is expedient to use the TEMP method; which allows determining the depth and types of anomalies for the search for methane accumulation zones.