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.%大牛地气田盒1段储层岩性为砂、泥岩互层,水平井在施工过程中易钻遇泥岩夹层,悬空侧钻是一种快速、经济的应对措施,且不对储层造成污染.DP22井在水平段施工过程中钻遇泥岩后退至砂岩井段应用了悬空侧钻技术,通过优选侧钻点、侧钻钻头和钻具组合,采用合理的造斜率及侧钻钻压,确保其继续在储层砂岩中钻进,侧钻过程中油气显示良好,实现了随钻点火,整个施工过程仅耗时3d,在侧钻之后直至完钻的最后4趟钻均能找到侧钻井眼并顺利下钻,侧钻井段总长972m,水平井段砂岩钻遇率达到了100％.DP22井悬空侧钻的顺利实施,确保了水平井段的砂岩钻遇率,最大限度地发挥了氮气泡沫欠平衡钻井技术在保护储层方面的作用,为今后水平井的实施积累了经验.
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