The crude stockpiles held by the country’s state-owned energy companies remain nearly full. Beijing appears not to have tapped its vast strategic reserves, and storage tanks at Chinese refineries are brimming with petrol, diesel and other refined products.
China was able to reduce imports so sharply in part because it had been buying more oil than it needed before the war. For years, it accumulated inventories whenever prices were low as part of a broader push to strengthen national self-reliance and improve its ability to withstand supply disruptions.
The article is contradicting itself. It is saying they are not tapping their reserves, because they bought excess before the war to accumulate inventories. Are they using their inventories or not? You can probably just sum up the whole article by saying they stored a lot of oil before the war (but are obviously using it if they are not relying on imports)