Difference in liquid supply capacity of coal seams and its influence on multi-layer drainage of coalbed methane: Taking the west limb of Guyi anticline in Daning-Jixian region as an example
CHAO Haiyan
WANG Yanbin
GE Tengze
HOU Wei
LI Yanfei
Abstract：Differences in the coalbed methane production of different multi-layer drainage wells in the west limb of Guyi anticline in Daning-Jixian region was studied.Based on production data and results of production profile logging interpretation,difference in liquid supply capacity of No.5 and No.8 coal seams and its influence on coalbed methane production of commingled producing well were analyzed.During the drainage process,big differences in liquid supply quantity of No.5 and No.8 coal seams will help reduce the permeability damage caused by stress sensitivity and fluid velocity sensitivity.No.8 coal seams with strong liquid supply quantity protects No.5 coal seams indirectly.The results indicate that water production of wells with big difference in liquid supply quantity of two seams is larger than that of wells with small difference.The bottom hole pressure of wells with big difference in liquid supply quantity drop to 2 MPa or so after four-year drainage,and gas production increases to 1 000 m3/d or above slowly,reducing the permeability damage caused by stress sensitivity and fluid velocity sensitivity and helping maintain high and stable yield.Due to differences in liquid supply capacity and quantity,pressure drop transmission speed of the two seams near the borehole zones is inconsistent,causing small amount of liquid intruding into the No.5 coal seam and the pressure recovers to some extent.When the damage caused by the stress sensitivity is reduced,the pressure drop transmission speed returns to a consistent state.The working fluid level and pressure in well bore continue to maintain the existing rate of decline,which will further enlarge the pressure drop range.
Keywords：coalbed methanemulti-layer drainagedifference in liquid supply quantitytransmission of pressure droppermeability
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：8( 606-613 )