Research On Displacement Efficiency Of Low Return Velocity Cementing In Front Of Kuqa Mountain

Although low-speed leak-proof cementing technology was adopted in front of Kuqa Mountain in Tarim to avoid the loss of cementing in the fourth and fifth openings of ultra-high pressure gas wells and realize one-time up-and-down,the problem of low wall shear stress of fluid during low-speed cementing and whether drilling fluid filter cake can be effectively cleaned on the wall can be solved.Cementing displacement efficiency directly affects the quality of cementing,and then has an important iMPact on the later development of oil and gas and the life of oil wells.According to the geological characteristics and construction conditions of this area,the low-speed cementing technology can effectively reduce annulus pressure and leakage risk.Firstly,the fluid rheological characteristics of drilling fluid,isolating fluid and cement slurry under borehole temperature and pressure during low-speed cementing are studied.It is proposed that the corresponding rheological model should be fitted by rheological measurement data in the range of low-speed cementing,and the corresponding rheological parameters should be calculated according to the actual low-speed cementing shear rate.The rheological model,rheological parameters and their effects on displacement flow pattern,cyclic pressure consumption and cementing displacement have confirmed the necessity and rationality of this new understanding.2)Based on wellbore data of block 4 and 5 of ultra-high pressure gas well in front of Kuche Mountain in Tarim and rheological parameters of drilling fluid,isolating fluid and cement slurry at low shear rate,a numerical simulation model of low-return rate cementing displacement has been established.The effects of drilling fluid,isolating fluid,cement slurry rheological properties,density difference,cementing displacement and wellbore enlargement rate on displacement efficiency of low-speed cementing are studied and obtained.3)Based on the influence law of various factors on displacement efficiency of low-speed cementing downhole,the pertinent technical measures to improve displacement efficiency of low-speed cementing in front of Kuche Mountain in Tarim are put forward,and good results are obtained in the field.Good application efficiency.The application of this technical measure provides a reliable theoretical basis and technical reference for further utilizing low-speed cementing technology to solve the problem of cementing leakage in the 4th and 5th opening of ultra-high pressure gas wells in Kucheshan,Tarim,and at the same time to improve displacement efficiency and cementing quality.