Exxon will most likely end up writing the whole thing off at zero. It will be lucky to recover a penny from this given the Venezuelan government's attitude towards foreign direct investment. The $7B represents about 2.3% of Exxon's total assets but as a charge-off it can take a hefty 70% from Exxon's quarterly net income if it hasn't already. BTW, Exxon's earnings look unusually even for the last four quarters. I wonder what accounting treatments make it so smooth. It's worth noting that XOM has a P/E of just over 10, not really a bargain among supermajors when its peers mostly trade at single-digit P/Es.
The other majors who continue to do business in Hugo Chavez's playpen must think that keeping a minority stake in a forced corporate marriage is preferable to a total loss. Socialism is stupid but Latin American despots find it useful. Good luck to any oil company that wants to throw good money after bad in Venezuela.
Full disclosure: No position in XOM at this time.