Oil is supposed to be a rare commodity, much like it is in the real world. It is completely unnecessary for the endgame in Buildcraft, and Forestry already adds Biofuel as a renewable alternative that's almost as powerful as Oil/Fuel, AND it adds Biomass as a less powerful alternative that requires less infrastructure. Add Oil Mystcraft pages? Biofuel is useless. Biomass is useless. The way you get Mystcraft pages now, you just keep creating random ages and raiding the Abandoned Libraries found within, until you get the Oil page, and bam, done.
Also, you will never need to travel 20k blocks to find an oil well. They're fairly common in Desert & Ocean biomes, and not that rare in Swamp and Jungle types biomes. ExtraBiomesXL adds tons of biomes that are similar to these i mentioned that also generate Oil in them rather commonly. In Oceans and Deserts, it's not unusual to find two Oil Wells sitting closer than 100 blocks to eachother, and in Oceans, especially, it's not unusual to find a single Oil Geyser with 2000~4000 buckets worth of oil in it, as well as double geysers.
The catch? It will eventually run out, and you will need to move your entire setup. Also, it's difficult to pump oil out of Oceans because the pump often pumps in the water instead of the oil, which clogs the pipes, meaning you'll need a secondary tank for water, or cordon off the Oil before you can really pump it out of the oil well reliably. Adding a Mystcraft page for Oil removes all of these drawbacks, which are meant to balance out the power of Oil/Fuel, and lets it simply become the all-powerful fuel source for MJ, forever.
Sure, you can create infinite Oil with bees already, but that means you will need to have done quite a bit of exploring already in order to get the T1 bees needed, plus a lot of bee breeding in the meantime, which is not an exact science, in order to get your Distilled Queens. The hassle and process you go through with bee keeping is the balancing factor in that. Mystcraft pages don't have that kind of balance, it's all RNG. You can find an Oil page in the first village you raid, or you can find it after 2 hours of searching in random Mystcraft ages. It's completely and utter random. The mod is not complete, it's balance is still off, and adding this will only contribute to increase the amount of imbalance the mod creates. It's already one of the most powerful mods available, it doesn't need anything else added to it in addition to that.