I've been stuck on this for a minute, I don't understand how to turn this into an equation??

Assume that a coal deposit is estimated to contain 100,000 tons of extractable coal. During the first year of mining, 1,000 tons of coal are removed from the mine. The next year, and every following year, the number of tons removed doubles so that 2,000 tons are removed in the second year, 4,000 in the third, and so on. In how many years will the entire 100,000 tons be removed?