Heat a small saucepan over low heat and add blueberries. Heat until the begin to bubble and burst, about 10 minutes, then mash with a fork. Add in ketchup, both vinegars, brown sugar, onion and garlic powder, ground mustard and worcestershire sauce. Whisk well to combine and break up blueberries and turn the heat up to medium. Heat until mixture bubbles, stirring every few minutes, then turn heat back down to low. Cook for 20 minutes, whisking every few minutes. Sauce will be slightly clumpy and thicker than regular BBQ sauce.