Résumé : The present work deals with the effects induced by nuclear deformations and electron correlations on the electron ground-state energies of low and multiply charged helium like ions. Numerical calculations of the ground state energies including mass corrections and polarization of the electronic system have been performed for such heliumoid ions with nuclear charge number from Z=2 to Z=118. A perturbation method has been developed based on a variational principle using explicitly correlated two-electron wave functions. The mass-polarization term accounting for correlation effects has been included for the first time in the minimization procedure. These effects have been found to be particularly pronounced for ions corresponding to nuclear magic numbers. The present method provides a general framework for high-precision calculations of plasma diagnostics.