X0306 4 2021-03-30 0 0001652133 Oasis Midstream Partners LP OMP 0001494083 Lou Michael H 1001 FANNIN STREET SUITE 1500 HOUSTON TX 77002 1 1 0 0 President Common units representing limited partner interests 2021-03-30 4 A 0 20712 0.00 A 45712 D On March 22, 2021, the Issuer entered into a Contribution and Simplification Agreement (the "Contribution and Simplification Agreement"), by and among the Issuer, OMP GP, LLC (the "General Partner"), and certain other parties thereto. Upon the consummation of the transactions contemplated by the Contribution and Simplification Agreement, which occurred on March 30, 2021 (the "Effective Date"), certain Class B Units representing membership interests in the General Partner that were previously issued to the Reporting Person by the General Partner were converted into and exchanged for restricted common units representing limited partner interests in the Partnership (the "Subject Units"). The Subject Units are subject to the following vesting schedule: (i) 34% of the Subject Units vested on the Effective Date, (ii) 33% of the Subject Units will vest on the first anniversary of the Effective Date and (iii) 33% of the Subject Units will vest on the second anniversary of the Effective Date. /s/ Nickolas J. Lorentzatos, attorney-in-fact 2021-04-01