Lead stories: BHP calls time on foray into US unconventionals. Macro: Brent-WTI spread widens ahead of Tropical Storm Harvey; oil and gas shares outperform broader market. Companies: Changes at the top at Chevron? Cairn and Premier post encouraging H1 results; Chinese NOC's report strong results, raise dividends. M&A: Statoil the latest Major to enter Vaca Muerta. Exploration: BHP announces US GoM discovery with Wilding-2 well.