| The solid content of conventional water-based drilling fluid is high,which leads to the low inhibition of the system and high stickiness.Clay particles are easy to adsorb on the surface of the drill bit,which restricts the increase of the drilling speed.Oil-based drilling fluid has a certain impact on the environment,its preparation,maintenance costs and harmless handling fees are high,which restrict its promotion and application.Studying the anti-high temperature non-solid drilling fluid with strong inhibitory ability and low adhesion has become an important technical way to further improve the drilling rate,shorten the drilling cycle,ensure the safety of underground and meet the requirements of protection reservoir.Formate drilling fluid without solid-phase which is a kind of water-based drilling fluid,is non-toxic and meets the environmental protection requirements.It also has good temperature resistant properties and hydraulic characteristics,nice rejection capability and the ability to fight pollutions,especially has favorable compatibility with the reservoir,all this make it has a good effect of reservoir protection.In this paper,the mechanism of solid-free formate drilling fluid has been studied,and the drilling fluid system with ideal high-temperature rheology,strong inhibition,anti-collapse and lubricating function has been selected through indoor study:the use of formate which has a higher degree of solubility as a weighting agent,and tackifier,fluid loss control agent,polymer alcohol reservoir protective agent compound used to reduce the water molecules to the formation of immersion,play a better inhibition,anti-collapse Role,while the ideal high temperature stability,to meet the environmental requirements,to avoid the conventional solid-phase drilling fluid damage to the reservoir.Field test results in the Longshen area of Jilin province show that the solid-free formate drilling fluid can effectively protect the reservoir and increase the yield per well. |
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