Research And Application Of Oil-based Drilling Fluid Leakage Prevention And Plugging Technology In Jinlong 2 Well Area

The third spud oil-based drilling fluid leakage of horizontal wells in Jinlong 2 well area occurs frequently.The success rate of one-time plugging is low,and the non-production time is greatly increased,resulting in significant economic losses and seriously affecting the drilling efficiency and well control safety.Firstly,through the statistical analysis of the on-site well leakage,the paper determines the main leakage layer,analyzes the characteristics of the leakage layer,and defines the causes of the well leakage.It is found that the leakage layers are mainly concentrated in P₃w₁and P₃w₂ of the Shang Wuerhe formation.The main causes of leakage are the development of formation micro fractures,narrow safety density window,the density is too high,the fracturing of adjacent wells and the distribution of some wells close to the fault.The reasonable control of drilling fluid density,the"high opening and low running"of the third spud oil-based drilling fluid density,and the early leakage prevention and plugging measures while drilling have been formulated.In this paper,through the particle size analysis,acid solubility,compatibility and plugging evaluation of leakage prevention and plugging materials,QS-2,elastic graphite,TP-2 and oxidized asphalt are are selected and form a leakage prevention and plugging formula while drilling:2.5%QS-2+1.5%elastic graphite+1%oxidized asphalt+1%TP-2.Through the indoor fracture plugging experiment,XZDL series plugging materials are optimized as the main agent,which is applicable to the plugging formula of 3-1mm and 2-0.5mm cracks,providing technical support for on-site leakage prevention and plugging.The field application shows that by preventing leakage while drilling in advance and reasonably controlling the drilling fluid density,the leakage rate in Jinlong 2 well area is reduced by 40.5%and the success rate of one-time plugging is increased by 35.18%,which effectively solves the problem of well leakage in well block Jinlong 2,shortens the drilling cycle,and improves the drilling efficiency and economic benefits.