MY-2井筒呼吸效应及识别

Identifying of Borehole Breath Effect in Well My-2

钻井发生井漏后钻井液回吐与溢流较难区分,影响现场制定针对性技术措施,存在较大井控风险。针对准噶尔盆地西部隆起乌夏断裂带二叠系风城组裂缝发育、欠充填、钻井易发生井漏的现象,从区域钻井地质特征、井内压力与钻井工况的关系等方面阐述了发生井筒呼吸效应的机理。通过分析关井压力变化、井口返出钻井液总量及返出过程中的变化趋势等,阐述了井筒呼吸效应与地层流体侵入导致溢流的异同点,提出了识别两者的依据。结合MY-2井筒呼吸效应实例介绍了现场处置方案和采取的技术措施,对该区域及相似地质条件钻井具有借鉴作用。

It is difficult to distinguish drilling fluid backflow and overflow after lost circulation in drilling,which affects the devel-opment of targeted technical measures on site,and there is a great risk of well control.In view of the phenomena of fracture develop-ment,underfilling and drilling leakage in the Permian Fengcheng Formation of wuxia fault zone in the Western uplift of Junggar ba-sin,the mechanism of wellbore breathing effect is expounded from the aspects of regional drilling geological characteristics,the rela-tionship between well pressure and drilling conditions.By analyz-ing the change of shut in pressure,the total amount of drilling fluid returned from the wellhead and the change trend in the return pro-cess,this paper expounds the similarities and differences between the wellbore breathing effect and the overflow caused by forma-tion fluid invasion,and puts forward the basis for identifying the two.Combined with the example of MY-2 wellbore breathing ef-fect,the on-site disposal plan and technical measures are intro-duced,which can be used for reference for drilling in this area and similar geological conditions.