Research On Pressure Control Technology Of Foam Material In Deep Water Wellbore

Thermal expansion of closed annulus fluid in deep water wellbore leads to Annulus pressure Buildup,which seriously threatens the wellbore integrity.The compressible foam material with hollow glass beads has the advantages of stable performance,strong compressive resistance,simple operation,and can be used for pressure control of closed annulus in deep water.At present,there are few researches on pressure control by using foam material.In this paper,the pressure prediction model in the sealed annulus with the foam material inside and optimization of the foam material were studied as follow:Based on the constitutive model of foam material,the experimental data of hydrostatic deformation of foam material were fitted,and the deformation expression of foam material volume was obtained.Combined with the annulus temperature prediction model and pressure buildup coupling model in the closed annulus,the temperature-pressure prediction model with foam material in annulus was established.The core algorithm considering the gradual deformation of foam material volume in annulus is established,and the annulus pressure control software is written,which can realize the temperature prediction,pressure prediction,foam material volume optimization and crushing pressure optimization.Combined with case,considering the maximum annulus pressure recommended by API standards and equivalent stress of casing,the placement depth,optimal volume and crushing pressure selection of foam materials are comprehensively analyzed,Optimization analysis of the case shows that in normal Wells,the installation of foam material with a volume of about 5% can control the APB.