Petroleum and Gas inventories reports

Hello guys, Can anyone explain to me the meaning of Gas and Petroleum reports? I mean, for example, if the inventories are low then this may push up petrol prices, then people should be taking money OUT of the market which would lead to prices falling down. On the other hand, the increase in oil prices may push up the securities of oil companies, which in their turn may bring the indexes up as well. Am I right or wrong? Thanks.