胜利油田水平井钻遇“流沙层”不增斜的预防及处理

Prevention and Treatment for Build-Up Rate Control in Drilling Flowing-Sandstone Formations in Shengli Oilfield

胜利油田一些区块在水平井钻井过程中经常遇到在增斜段或水平段不增斜的砂岩,即"流沙层"。由于不增斜,严重影响了井眼轨迹控制和中靶以及水平井的开发效果。从地层特性和造斜工具的选择上分析了胜利油田水平井钻遇"流沙层"不增斜的原因:砂层埋深浅且疏松;钻速过快;井眼尺寸大;造斜工具选择不当。针对这些原因,提出了在设计和选择工具时的预防措施和施工时提高造斜率的主要技术措施,以2口井为例说明了如何预防和处理钻遇"流沙层"不增斜的问题及采取措施取得的效果,最后指出措施虽然效果明显,但是增加了起下钻的次数,延长了钻井周期,建议开发可以在井下操控的专用动力钻具,以提高"流沙层"的造斜率。

During horizontal well drilling in some of the blocks in Shengli Oilfield,no build up rate often occurred during the buildup or horizontal segments in the sandstone,namely flowing sandstone formation.The control of wellbore trajectory and hitting target,and the development results of horizontal wells were impacted greatly.Reasons of no build up rate in these formations were analyzed from the formation characteristics and build-up tools,including unconsolidated sandstone,rapid drilling speed,large hole,improper build up tools.Preventions used in design and selection tools,and main treatments to increase built-up rate used in drilling operations were proposed.Two wells were used to demonstrate the results of how to prevent and treat the problem of drilling in the no build-up formation.Though the results were obvious,the number of round trip was increased and the drilling cycle was prolonged too.It was suggested that the special mud motors operated downhole should be developed to improve build up rate in flowing sandstone formations.