Research On Mechanism And Regularity Of Hydrostatic Pressure Transfer In Horizontal Well Cement

The solidification process of cement slurry is complex,including the process of cement particle dissolution,hydration,crystallization and hardening.During the solidification of cement slurry,the pressure transfer process changes with the hydration process.In this paper,the relevant experiments were carried out,such as the test of static gel strength development,the microstructure test of cement slurry,the pressure transfer test of cement slurry,and so on.By means of mathematical statistics and linear regression,the experimental data was processed and analyzed and kinds of curves were obtained.The mathematical model of hydrostatic pressure transfer of cement slurry in horizontal well was established.The hydrostatic pressure transfer mechanism and law of cement slurry in horizontal wells were researched on.The results shown that during the solidification of cement slurry,the internal stress of cement slurry changed with the increase of hydration time.During the initial hydration of cement slurry,the pores in the cement slurry were connected,and the pore pressure curves was showed as a slight downward trend.When the cement hydration stage entered into the accelerate hydration reaction stage,A large number of cement particles were formation,the total solid content rapidly increased and lots of closed die pores were appeared.At this point,the pore pressure curve decreased rapidly,and the phenomenon of non-uniform stress transfer occurred in the cement slurry.When the connected pore volume of cement was less than 5%,the internal conduction stress was very weak,pore pressure curve tended to be gentle.The pressure transfer mode was changed from the fluid pressure transmission to the porous medium pressure transmission.