  The aim of this article is to study deformation theory of trianguline B-pairs
for any p-adic field. For benign B-pairs, a special good class of trianguline
B-pairs, we prove a main theorem concerning tangent spaces of these deformation
spaces. These are generalizations of Bellaiche-Chenevier's and Chenevier's
works in the Q_p case, where they used (\phi,\Gamma)-modules over the Robba
ring instead of using B-pairs. As an application of this theory, in the final
chapter, we prove a theorem concerning Zariski density of two dimensional
crystalline representations for any p-adic field, which is a generalization of
Colmez and Kisin's results in the Q_p case.
