Port-oak Porter - wood chips

There are some breweries who mature their beer in wood casks that have previously held whiskey, brandy or port. The same effect can be achieved by using wood chips in the glass carboy, although don't fancy using oak essence or something like that. Using wood chips is supposed to assist in yeast growth and fermentation too. Most recipes I've read say to use somewhere between 2 and 6 ounces in a 5 gallon batch. It must be about surface area though rather than weight, so you'd probably get more flavour out of 2 oz oak chips that are in tiny pieces rather than 1 chunk weighing 6 oz, so I'll see how small I can get the pieces. I've read about brewers using various woods such as cherry or beech but I like the vanilla taste that you get from oak or the nutty/coffee taste it gives when roasted. I've used charred oak pieces in a elderberry and blackberry port before now which worked well. For the porter, I'll sterilize the oak chips in the oven for half hour but at around 150 deg C so there is no toasting. It should take a month or two to mature. Thinking about the dates, I'd better get it on if it's going to be ready for Christmas.