Hello,

A way, (maybe not the best) is to add a function field with a function search to adapt the query.

And you can Add a filter "By year" in search view to make it invisible for end user...

    def _search_year(self, cr, uid, obj, name, args, context):
        x = [('date_beg', '>=', args[0][2]), ('date_end', '<=', args[0][2])]
        res = self.search(cr, uid, x, context=context)
        return [('id', 'in', res)]

...

    'date_beg': fields.selection([(num, str(num)) for num in range(1900, (datetime.now().year)+1 )], 'Año inicial'),
    'date_end': fields.selection([(num, str(num)) for num in range(1900, (datetime.now().year)+1 )], 'Año final'),
    'date_search': fields.function(lambda self: self, string='Año search', type='integer', fnct_search=_search_year)

Let us know it it works ...