What is the relationship between cosl and CNOOC?

Cosl is a subsidiary of CNOOC and cosl is a listed company. There are seven professional subsidiaries including offshore drilling and oilfield chemistry. This is a great company. However, in recent years, due to the wrong operation of the company's leadership (which can't be described in detail), the shrinking business volume in the international market and the overall environmental factors of CNOOC (there is no development of new oil fields), the benefit of cosl has declined, but the thin camel is bigger than the horse, and it is generally good.