According to the merger agreement, Oxy is required to keep APC employees' salaries the same for one year. Read it for yourself on EDGAR
https://www.sec.gov/Archives/edgar/data/773910/000119312519144402/d745029dex21.htm
Oxy/APC AGREEMENT AND PLAN OF MERGER 5/9/2019
Section 6.6 Employee Benefits
(b) For a period of one (1) year following the Effective Time, Parent shall continue to provide to each individual who is employed by the Company and the Company Subsidiaries as of the Effective Time who remains employed with Parent or any Subsidiary of Parent (“Affected Employees”), for so long as such Affected Employee remains employed by Parent or any Subsidiary of Parent during such one (1) year period, with: (i) base compensation that is no less favorable than was provided to the Affected Employee immediately before the Effective Time...