Yes, you can.
If you dont understand any sections please let me know and I will explain - I don't know your knowledge base so it may need a bit more yet

I will assume that you have a standard summer time duration for a well- lets say it is100 days, soin winter it will take 115 days. Project by default uses an 8 hr day, and this forms the base calendar. If you know the winter months where the extra 15% applies, you can create a calendar (you could modify the "standard" one, but that can complicate things). The calendar will determine the working hours, and if you have less hours, then the time goes up.
Create a new calendar, call it "wells" or whatever your preference is, then change working times. Select the winter month period, and change the last time from 17:00 to 15:48. This reduces the day by 1hr 12 mins, which is 15%. Assign the new calendar to each well task, and it will automatically extend duration by 15%- it has less hours for the same work, so the duration must extend.

Again if that flew over the head, I can give more detail if you let me know where you need it- otherwise, good luck