Simon Henry, the Chief Financial Officer (CFO) of oil giant Shell, reinvested dividends in the company the same day that it announced a significant deep-water oil discovery in the Gulf of Mexico.Dividends received from Shell's 'class B' shares acquired under an employee share plan were then automatically used to purchase more shares, the firm said on Thursday, citing a transaction that occurred the day before.Henry, who joined the board as CFO back in May 2009, bought reinvested £56,495 received in dividends to buy 2,605 shares in the firm at 2,168.7p each.The move, which followed a near 9.0% fall in the share price since mid-May, came on the same day that Shell said that Vicksburg well located offshore in the De Soto Canyon Block, Gulf of Mexico, had encountered more than 500 feet of net oil pay.Shell estimates that the Vicksburg 'A' well could hold over 100m barrels of oil equivalents, adding to the 500m barrels of potentially recoverable resources that have already been discovered and appraised at the nearby Appomattox discovery.Top Director BuysStaffline Group (STAF) Director name: Mr Andy HogarthAmount purchased: 350,000 @ 411.50p Value: £1,440,250Staffline Group (STAF) Director name: Ms Diane MartynAmount purchased: 350,000 @ 411.50p Value: £1,440,250Royal Dutch Shell 'B' (RDSB) Director name: Mr Simon HenryAmount purchased: 2,605 @ 2,168.73p Value: £56,495Iofina (IOF) Director name: Mr Stuart EatonAmount purchased: 26,500 @ 172.80p Value: £45,792Oxus Gold (OXS) Director name: Mr Richard B SheadAmount purchased: 750,000 @ 1.65p Value: £12,375Top Director SellsIofina (IOF) Director name: Mr Stuart EatonAmount sold: 26,500 @ 166.00p Value: £43,990Euromoney Institutional Investor (ERM) Director name: Mr Neil OsbornAmount sold: 4,000 @ 981.00p Value: £39,240