Companies that thought they had found a relatively easy way to move crude from the booming oil fields of North Dakota to the West Coast are encountering obstacles. Half a dozen companies are trying to build rail terminals on the coast of Washington state to receive trainloads of crude from the Bakken field in North Dakota. The oil would then be transferred to ships and barges that could carry it to refineries in the Pacific Northwest or south to California. Analysts say regulatory hurdles make it difficult to build the necessary rail yards and tank farms in California, and it’s more expensive to ship crude there. But getting a permit in Washington is proving more challenging than companies expected.