It could be oil they are digging for, but more likely it's water. Yet another police check 15k out of town took only a few minutes. 25k later a car with 5 cops caught up and wanted to check my passport again. I told them nothing had changed since an hour ago but they insisted. Obviously they had heard of me and decided to do an excursion to see me making up the passport excuse because they hardly looked at it and turned back afterwards.... harmles but pretty ridiculous....