Exxon Mobil signaled on Monday that lower oil and gas prices could cut its second-quarter earnings by about $1.5 billion from the previous quarter’s level.The earnings snapshot from the largest US oil producer is closely watched for clues on how the broader oil sector will fare when companies begin releasing quarterly results in a few weeks.Benchmark Brent crude prices averaged$66.71 per barrel during the April to June quarter, an 11% decline from the previous quarter, as more crude supply from the OPEC+ g ...