Research On Main Controlling Factors And Development Dynamic Characteristics Of Coalbed Methane Production Capacity

Based on the geological and drainage characteristics of the coal reservoirs in Baode District on the eastern margin of the Ordos Basin,the main controlling factors of coalbed methane productivity in Baode block were systematically analyzed from three aspects:geological conditions,engineering technology and drainage control.The quantitative analysis of factors affecting production capacity was carried out by grey correlation analysis.Then,from the aspects of reservoir pressure change,cross-well interference characteristics and dynamic evaluation of reserves,the dynamics of coal reservoirs during coalbed methane emission and production were revealed.Change characteristics.The following results have been achieved:(1)Through the systematic research on geological conditions,engineering technology,rainage and production control,the main controlling factors and mechanism of coalbed methane productivity in Baode block are revealed,and these factors are quantitatively studied by grey correlation analysis.(2)Coal seam thickness,groundwater fluid potential,gas content,permeability and near reservoir ratio are the main geological factors affecting the productivity of Baode block coalbed methane;well spacing,total fracturing fluid volume and sand addition are the main factors affecting productivity.Engineering and technical factors;downhole pressure drop rate,hydrodynamic water level decline rate and casing pressure directly affect coalbed methane production capacity.The main controlling factors of coalbed methane productivity from strong to weak in the study area are:near water storage rate>groundwater fluid potential>equivalent thickness>equivalent gas content>equivalent sand content>equivalent fracturing fluid volume>equivalent permeability>average Well spacing.(3)Based on the in-depth analysis of typical cases,a pressure drop model was established to explain the dynamic characteristics of coal reservoirs during coalbed methane emissions and production.This paper reveals the characteristics and laws of reservoir pressure changes during coalbed methane emission and production,simulates the change of single well reservoir pressure,and proposes the influencing factors of pressure drop funnel.