X0306 4 2020-10-01 0 0001486159 Oasis Petroleum Inc. OAS 0001494078 Reid Taylor L 1001 FANNIN ST, STE 1500 HOUSTON TX 77002 1 1 0 0 President and COO Common Stock 2020-10-01 4 S 0 279316 0.21 D 1192569 D Common Stock 2020-10-02 4 S 0 778349 0.20 D 414220 D Common Stock 2020-10-02 4 S 0 548188 0.22 D 0 I by West Bay Partners, Ltd Represents weighted average price of open market same day sales. Sales of shares took place at actual prices ranging from $0.21 to $0.22 per share. Full information regarding the number of shares sold at each separate price will be provided upon request by the Commission staff, Oasis Petroleum Inc. or an Oasis Petroleum Inc. shareholder. A limited partnership formed for family investment purposes. The sole general partner of West Bay, a Texas limited liability company, is controlled by the reporting person and his wife, and the limited partners of West Bay consist of the reporting person, his immediate family members and trusts formed for their benefit. /s/ Nickolas J. Lorentzatos, as attorney-in-fact 2020-10-02