Identification of aquifers influencing the drainage of coalbed methane wells in Shouyang exploration area,Qinshui Basin

Identification of aquifers influencing the drainage of coalbed methane wells are essential for diagnostic of well performance,selection of well sites / coalbeds for development operations and for fracturing design. Facing to the high water production problem in Shouyang CBM Exploration Area,In this article,regional hydrodynamic head and en- ergy distribution characteristics,aquosity of snadstones and limestones in the coal measures,lithological association surrounding the target coals,hydraulic communication of coals with the surrounding aquifers and detailed analysis of water sources of typical wells were comprehensively studied. It is recognized that regional hydrodynamics and permea- bilities of coalbed reservoirs control the average water production level,while the difference of water productions among wells are mainly controlled by local geological and engineering conditions (faults,hydraulic fractures types and height, and lithological assemblage surrounding the target coals) and hydraulic fractures are one mode,besides faults,of hy- draulic communication between target coals and their surrounding aquifers. It is finally concluded that the sandstones in coal measures are the main water source layers and the limestones in Taiyuan formation has weak influence on the well drainage and water production. It is suggested that the selection of well sites / coalbeds for CBM development oper- ations and fracturing design should be relied on the vertical combination of target coals and surrounding sandstone aq- uifers.