  Annual variations of interstellar scintillation can be modelled to constrain
parameters of the ionized interstellar medium. If a pulsar is in a binary
system, then investigating the orbital parameters is possible through analysis
of the orbital variation of scintillation. In observations carried out from
2011 January to 2020 August by the European Pulsar Timing Array radio
telescopes, PSRs~J0613$-$0200 and J0636+5128 show strong annual variations in
their scintillation velocity, while the former additionally exhibits an orbital
fluctuation. Bayesian theory and Markov-chain-Monte-Carlo methods are used to
interpret these periodic variations. We assume a thin and anisotropic
scattering screen model, and discuss the mildly and extremely anisotropic
scattering cases. PSR~J0613$-$0200 is best described by mildly anisotropic
scattering, while PSR~J0636+5128 exhibits extremely anisotropic scattering. We
measure the distance, velocity and degree of anisotropy of the scattering
screen for our two pulsars, finding that scattering screen distances from Earth
for PSRs~J0613$-$0200 and J0636+5128 are 316$^{+28}_{-20}$\,pc and
262$^{+96}_{-38}$\,pc, respectively. The positions of these scattering screens
are coincident with the shell of the Local Bubble towards both pulsars. These
associations add to the growing evidence of the Local Bubble shell as a
dominant region of scattering along many sightlines.
