关键词: 深井, 欠平衡钻井, 环空岩屑, 井底压力, 负压控制, 影响因素

Abstract: The pressure survey data in bottom hole were analyzed, and a computing method for annular cuttings effecting pressure increment in bottom hole was proposed. The responding calculation software was worked out. The analysis indicates that the actual annular cuttings in bottom hole have a great influence on the negative pressure at bottom. For deep wells of 4000-5000 meters in depth, when drilling rate is up to 10 meters per hour, the pressure increment in bottom hole resulted from annular cuttings is up to 3-4MPa and even higher. In order to control the negative pressure, the influence of annular cuttings should be considered. For different situations, the different control methods should be adopted. This methodology was applied to under-balanced calculation and negative pressure control in bottom hole in Daqing Oilfield. The negative-pressure control for under-balanced drilling in Daqing Oilfield was improved.

Key words: deep well, under-balanced drilling, annular cuttings, bottom hole pressure, negative-pressure control, influence factor