Properties of cesium formate based drilling and completion fluid and its application

While drilling oil and gas wells with high temperature and high pressure,the conventional drilling and completion fluid with high density can not fulfill the requirement to develop such wells due to its high content of barite and degradable polymers under high temperature.Yet cesium formate is capable of freely regulating the density of drilling and completion fluid,greatly enhancing the high temperature stability of polymers,preventing the drilling tool from corrosion,when its density is between 1.0 and 2.3 g/cm3.Therefore,cesium formate based drilling and completion fluid has become an ideal drilling and completion fluid system for drilling complicated wells including highly deviated wells and deep slim hole wells.The application of the cesium formate based drilling and completion fluid,the physical properties of cesium formate,the basic features of the fluid,the formulation of the fluid and its performance are introduced in this paper.It has been applied to many oil and gas wells with high temperature and high pressure abroad.Results show that it features in simple formulation,excellent hydraulic and rheological performance.It can not only better fulfill the requirement of drilling and cementing,but also protect reservoir and can be a good reference to solving the problems of wells with high temperature and high pressure at present.