Finite Element Approach to Predict the Effect of Annular Pressure Buildup on Wellbore Materials

Abstract

Annular pressure build up (APB) is caused by thermal expansion of wellbore fluid enclosed in an annulus experiencing cyclic thermal loads due to production and injection. This may lead to significant damage to the cement sheath causing zonal isolation issues and may also cause casing collapse/burst. This work focuses on using an engineered approach based on finite element modeling to analyze the cement sheath response to APB loads for the life of the well. Actual field data of pressure build up and bleeding rates are used in our analysis. The present study provides a methodology to analyze cement systems for their ability to survive APB conditions. A proper knowledge of response of wellbore materials (cement and casing) to APB can be helpful in design of better cement systems and in selection of appropriate casing materials which can withstand the APB conditions. It has been observed from our comparative study of two cement systems that the stresses in the elastic cement are less than those in conventional cement. A parametric study has also been performed to analyze the effect of different cement properties. The results are quantified in terms of stresses experienced by cement sheath and casing. This study is based on fundamental principles of structural mechanics, thus providing more reliable predictions. It helps in deciding the appropriate cement system for a predetermined production/injection rate or can give a recommendation of production/injection rates for a given cement system such that damage to the cement sheath can be avoided.

Study on sealing integrity of cement sheath in ultra deep well reservoir reconstruction

“…During the fracturing process, the combined action of internal high pressure and local external loads may cause deformation of the downhole casing. Second, Jandhyala, Chiney, and others studied the effect of the increase in confined water flow pressure (APB 28 ) in the sealed casing cement sheath voids on the wellbore and believed that under extreme conditions, the APB effect might cause serious damage to the cement sheath and casing 29,30 . Dusseault et al, 31 Daneshy, 32 and others believe that during the fracturing operation, injection of fracturing fluid will cause cracks to appear between the casing and formation, resulting in a pseudo‐openhole environment around the wellbore.…”

Study on annular pressure buildup phenomenon in subsea wells considering the effect of cement

“…The resilient cement was considered able to withstand a bigger APB load than conventional cement. 18 Williamson et al presented valuable laboratory tests about APB. Eight fluid combinations were used in the test including the foamed fluid.…”

Modelagem Termo-Mecânica Do Crescimento De Pressão Em Anulares Confinados, Frente a Formações Salinas

“…A equação 4-8 relaciona a expansão volumétrica com o aquecimento do fluido (43). Integrando-se esta equação ao longo de todo o anular o aumento total de volume devido ao incremento de temperatura pode ser determinado.…”