Application and knowledge from suspended sidetracking technology at the well DP-22 in Daniudi gas field

The He 1 reservoir of the Daniudi gasfield consists of layers of sand and mud, so the mudstone layers would be encountered during drilling horizontal well. Suspended sidetracking, without formation damage, is a quick and economic measure for this problem. After mudstone layer was encountered when drilling the horizontal section of Well DP22, it was draw back to the sandstone layer to implement suspended sidetracking. It was made sure that the bore hole still in reservoir by means of choosing sidetracking point, bit and BHA, as well as buildup rate and bit weight. Good oil/gas flow was observed during sidetracking, and gas flaring was performed while drilling. The operation covered just 3 days and it’s successful in finding the sidetracking point in the last four times of running into the hole after sidetracking. As a result, 972 meters of hole section was sidetracked and 100% of sandbody penetrating ratio was achieved. The success of suspended sidetracking at Well DP-22 guaranteed the sandbody penetrating ratio of the horizontal section, as well as maximized the function of underbalanced drilling with nitrogen foam for formation damage control. It will provide experiences for subsequent operations of horizontal well drilling in the field.