Application of Conventional Coring Tools in Coal Seams in Yanqi Basin

Coring operation in coal seams is very difficult as they are very loose. Coring operation with conventional tools cannot achieve satisfactory recovery rate in coal layers. Several special coring technologies have been developed while the special coring tools are complex and very costly. In Aug. 2002, Henan Petroleum Drilling Engineering Company modified the conventional coring tools. Through optimization of field operation, they were successfully used to core the coal seams in Well B1313 in Ba-olang oilfield, Yanqi basin and the yield was up to 99. 66%. It provides a new way for coring of loose or fractured formations.