Application of wireline coring technology in coalbed methane well DP1

The wireline coring technology applied in the coal seam section of coalbed methane well technically has the advantage of taking cores inside the drilling pipe without making a trip, but the conventional wireline coring tool is faced with the problem of low core recovery. Drilling bit and core catcher of the wireline coring tool were improved. The drilling bit was reconstructed into a shuttle shape, the top was modified into a discontinuous ring, a water channel was set between teeth, and the structure of 8 blades and 4 composite blocks was changed into that of 6 blades and 6 composite blocks to strengthen its aggression. In addition, the inner nozzle was removed to decrease the erosion on cores. The core catcher was improved into the two-in-one structure of slip collar and basket claw to enhance its universality. And combined with the optimization of drilling parameters, the core recovery is increased to 75.68%. In the process of coring construction in coalbed methane well DP1, the research results play an import role in accurately understanding the situations of roofs and floors and acquiring the gas bearing parameters of coal seams.