Is this for a five gallon batch? Oak chips have A LOT more surface area than oak cubes. You can easily overwhelm a porter with whiskey oak flavors using 2 ounces of oak chips. I only use one ounce in my wee heavy for five to seven days, which is a MUCH higher gravity beer than a porter. Steam sanitize your oak chips in the microwave by nuking them with some distilled water for 4-5 minutes, then let them soak in about an ounce or two of your favorite whiskey or bourbon. I use two mini bottles of Johnny Walker red label. Cheap and easy.
I let my oak chips soak for about a week in the bourbon in a mason jar, and then pour them into a sanitized muslin hops bag. I also put a weight into the bag so it sinks into the beer (glass marbles, quartz rock, anything easily sanitized and chemically inert). Toss your hops bag into your primary fermenter about a week prior to bottling and start sneaking some samples with a wine thief about four days into the soak. In my Wee Heavy, it usually takes five to seven days for it to just start tasting over-oaked. This is right where you want it because the oak flavors will mellow and fade as the beer ages. Taste testing is the key, just don't toss it in and pray that it will work. You'll wind up with liquid wood.
add it to the secondary
