Turkey-Cyprus dispute: Why are the two countries arguing over drilling rights?

Source:Euronews Date:26Jun2019

Good background on Cyprus  conflict, as well as EU stane. Note the paragraph:

In a statement on the issue after the European Council summit on Thursday it said it would ask its foreign service, the European External Action Service, to put forward options.

One senior EU official said that, aside from sanctions, one option was to end talks with Turkey over extending a customs union, which already allows tariff-free trade with the EU for industrial goods but not services or agriculture.

Another option could be formally suspending Turkey’s status as an official candidate to become a member of the European Union, although talks have been frozen for over a year due to concerns about the direction of President Recep Tayyip Erdogan’s government.