涠洲某油田A9井钻孔管柱下入技术

涠洲某油田A9井是位于广西北海北部湾的大斜度生产井,采用裸眼下入?178 mm钻孔管柱完井。A9井的特点是目的层压力系数高、钻井液密度高、黏度和切力大、井眼曲率大、井斜角大、水平段长、目的层为大段泥岩、页岩等,综合分析认为主要的完井技术难点有钻孔管下入摩阻大、井控和储层保护难度大、下钻激动压力和循环压力高易造成悬挂封隔器中途坐封等。针对以上难点,对钻孔管柱下入难度进行了分析,计算了管柱下入摩阻,并优化了管柱配置,采用具有储层保护效果的钻完井液体系和特殊结构的悬挂封隔器总成,从而将管柱顺利下入到位,并获得理想的油井产量。该技术为同类复杂井况条件下的钻孔管柱下入设计与施工作业提供参考。

Technique for borehole string running in Well A9 of one oilifeld in Weizhou

Well A9 in Weizhou is a highly deviated production well in the Beibu Gulf of Beihai, Guangxi province. It was completed by running ?178 mm string in openhole. Well A9 was characterized by high pressure coefficient of target zone, high drilling fluid density, great viscosity and shearing force, large dogleg, large hole inclination angle, long horizontal section and the target zones being mostly large sections of mudstone and shale. Comprehensive analysis shows that the major difficulties in completion technique include great friction when borehole string is run, difficulty in well control and reservoir protection, high surging pressure and circulation pressure during tripping in which may cause the suspension packer to set midway. In view of the above difficulties, analysis was conducted to the difficulties in running borehole string, the string running friction was calculated and the pipe string configuration was optimized. The drilling and completion fluid systems which could protect the reservoir and the suspension packer assembly with special structure were used, hence the pipe string was run smoothly and satisfactory oil well production was obtained. This technique provides a reference for the running of borehole string and tripping jobs under similar complex downhole conditions.