Research On The Technology Of Well Bore Stability Drilling Fluid For Long Open Hole In Jinlong 2 District

Jinlong 2 wells drilling with no intermediate casing have long open hole formation,soak a long time,and prone to borehole collapse.According to the low pressure bearing capacity of underground strata,the use of density anti-collapse cannot meet the needs of these new wells.Chemical collapse prevention becomes necessary.According to "multivariate cooperation" principle,the technical countermeasures of "physical and chemical cementing,density support,hydration inhibition and chemical equilibrium" are determined.In view of the geological characteristics of Jinlong 2 well area,additives such as inhibitors,coating agents and plugging agents for drilling fluid formulations were optimized.Potassium-calcium based drilling fluid system performance was further enhanced by inhibiting and carrying rock technologies,and form the multivariate cooperation drilling fluid system: By cation emulsified asphalt(sulfonated asphalt powder)and natural asphalt to improve the quality of the cake,plugging collapse prevention capability;KCl,amine inhibitors,organic salts and preferred coating agent synergistic enhanced inhibition and coating capacity,make full use of the multicoordinated drilling fluid system’s anti-collapse ability.Also add a tackifier which further improves the space grid structure of the fluid system,to enhance carrying capacity.The multivariate cooperation drilling fluid system is evaluated,and its inhibition ability,plugging capacity and rheological characteristic can meet the requirement of long open hole caving drilling.