Ltd. Four sources who had awareness on the matter stated that Sonangol, China Aviation Oil, and PTT International no longer had any outstanding amounts with ZenRock. PetroChina International Singapore Pte Ltd, a unit of PetroChina, South Korea's Daelim Corp, Singapore, and China Aviation Oil (Singapore) Corp are also included in the list of unsecured creditors. "These trade creditors are unsecured, but the obligations are mostly matched against incoming receivables," ZenRock said in the court filing.