A well packer for high pressure and temperature use having a tubular mandrel, upper and lower slip assemblies in spaced relation on the mandrel and a high temperature and pressure seal assembly including a plurality of annular elements of different elasticities mounted on the mandrel between the slip assemblies. The slip assemblies are arranged so that the lower slip assembly sets first and the upper slip assembly last while the upper slip assembly releases first and the lower slip assembly releases last when pulling the packer. The upper slip assembly includes a collet expander wedge and a support ring for holding the collet wedge expanded and releasing the collet wedge in running and pulling the packer. The packer is designed for temperatures at least as high as 600.degree. F. and pressures of at least 5000 psi.