Utilize the input text as a context reference, choose the right relationship between ADNOC and Abu Dhabi from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

We are currently providing facility management services in 3 countries with blue chip clients, including the Abu Dhabi National Oil Company, ADNOC, for its entire portfolio of ADNOC facilities.

Answer: headquarters_location