Melt butter in a Dutch oven over medium heat; stir in onion, jalepeno peppers, celery, and a pinch of salt. Cook until onions are soft and translucent, 7 to 10 minutes.
Stir seafood seasoning and cayenne pepper into onion mixture; cook for 30 seconds.
Sprinkle flour over onion mixture; cook and stir until mixture is slightly thickened, about 2 minutes.
Pour 2 1/2 cups water, 1/2 pound corn kernels, and 2 ounces crabmeat into the onion mixture; increase heat to medium-high and bring to simmer.
Place 1 cup water, 1/2 pound corn kernels, and garlic into a blender. Cover and puree until smooth.
Pour corn puree into the Dutch oven and bring mixture to a boil. Reduce heat to low; simmer until chowder is thicker and the color deepens, about 45 minutes.
Stir 6 ounces of crabmeat, paprika, and heavy cream into chowder. Season with salt and pepper to taste; garnish with green onions and a pinch of cayenne pepper.