Abstract:Formate drilling fluid system has the characteristics of bit cleaning ability, inhibition of mudstone dispersion, improvement of formation stability, and improvement of additive temperature adaptability, etc. In the construction of extended reach well, the system even has lubrication and wear reduction effect similar to that of oil-based system. Therefore, formate system is gradually widely used in drilling sites. Among them, the operation of replacing KCl with HCOOK to increase K+ content in liquid phase is the most common. However, in the actual construction, it was found that the solid phase content of drilling fluid with formate was seriously deviated from the real situation, and the commonly used salt content correction means were no longer suitable for drilling fluid system containing formate. The solid phase content of drilling fluid is an important index to evaluate the maintenance level of drilling fluid performance, and its regulation is correlated with the rheological properties, colloid stability and formation plugging ability of the system to varying degrees. The inferior solids in its solid phase composition have a particularly great impact on the fluidity of the drilling fluid system. Accurate determination and analysis of various solids in the solid phase composition can improve the application level of drilling fluid. It is of great significance to reduce the construction complexity. Therefore, it is necessary to correct the solid phase content measurement errors caused by formate, so as to avoid misleading the field maintenance operation and performance parameter control. Based on the experimental data, the author carried out data fitting for the change trend of volume and density caused by soluble salt such as HCOOK, and proposed a complete treatment method for the correction of solid phase content of drilling fluid system containing HCOOK. After combining the treatment results with the actual construction data on site, It is confirmed that the correction value of solid phase content obtained by using the calculation method given in this paper is consistent with the actual situation, and can be used to guide the field maintenance construction.