Wireline coring problems and solutions in continental sedimentary formation drilling

Abstract:

In the past two years， scores of CBM parameter wells with a depth of 1500m were drilled in the periphery of Yuka Coalfield， Dachaidan， Qinghai province， and wire line core drilling was conducted as per the geological design requirements. Drilling results showed that there were many down hole accidents with long drilling periods and low borehole completion rates. This paper analyzes the problems with drilling of JLSZK2 borehole， including diameter enlargement， hole wall clearance， excessive core wear； in addition， with regard to the problems with other borehole drilling in the mining area，experiences are summarized on how to perform wire line coring with high efficiency and high-quality in continental sedimentary formation.

Key words:CBM parameter well;wire line coring;diameter enlargement;scaling on the inner wall of drill pipe;solid content