X0306 4 2022-02-01 1 0001652133 Oasis Midstream Partners LP OMP 0001486159 Oasis Petroleum Inc. 1001 FANNIN ST., SUITE 1500 HOUSTON TX 77002 0 0 1 0 0001494070 Oasis Petroleum LLC 1001 FANNIN ST., SUITE 1500 HOUSTON TX 77002 0 0 1 0 0001717320 OMS Holdings LLC 1001 FANNIN ST., SUITE 1500 HOUSTON TX 77002 0 0 1 0 0001902823 Oasis Investment Holdings LLC 1001 FANNIN STREET SUITE 1500 HOUSTON TX 77002 0 0 1 0 0001525815 Oasis Petroleum North America LLC 1001 FANNIN STREET SUITE 1500 HOUSTON TX 77002 0 0 1 0 Common units representing limited partner interests 2022-02-01 4 D 0 33846032 27.48 D 0 I See Footnote On February 1, 2022, pursuant to that certain Agreement and Plan of Merger, dated as of October 25, 2021 (the "Merger Agreement"), by and among Oasis Midstream Partners LP ("OMP"), OMP GP LLC, Crestwood Equity Partners LP ("Crestwood"), Project Phantom Merger Sub LLC, Project Falcon Merger Sub LLC and Crestwood Equity GP LLC, (i) each Sponsor Unit (as defined in the Merger Agreement) issued and outstanding immediately prior to the Effective Time (as defined in the Merger Agreement) was converted into the right to receive 0.7680 common units representing limited partner interests in Crestwood ("Crestwood Common Units"). On January 31, 2022 (the last trading day prior to the Effective Time), the closing price of the Crestwood Common Units was $27.48. This Form 4 is being jointly filed by Oasis Investment Holdings LLC ("OIH"), Oasis Petroleum North America LLC ("OPNA"), OMS Holdings LLC ("OMS Holdings"), Oasis Petroleum LLC ("Oasis Petroleum") and Oasis Petroleum Inc. ("OAS"). As of the Effective Date, OMS Holdings directly owned 21,846,032 common units representing limited interested in OMP ("OMP Common Units") and OIH directly owned 12,000,000 OMP Common Units. OMS Holdings is the managing member of and owns an 87.3% membership interest in OIH. OPNA owns the remaining 12.7% membership interest in OIH. Oasis Petroleum directly owns 100% of the outstanding membership interests in each of OMS Holdings and OPNA, and OAS directly owns 100% of the outstanding membership interests in Oasis Petroleum. (Continued from Footnote 2) Accordingly, OAS, Oasis Petroleum, OMS Holdings and OPNA may be deemed to be indirect beneficial owners of the securities of the Issuer held by OIH, and OAS and Oasis Petroleum may be deemed to be indirect beneficial owners of the securities of the Issuer held by OMS Holdings. /s/ Nickolas J. Lorentzatos, Executive Vice President, General Counsel and Corporate Secretary of Oasis Petroleum Inc. 2022-02-03 /s/ Nickolas J. Lorentzatos, Executive Vice President, General Counsel and Corporate Secretary of Oasis Petroleum LLC 2022-02-03 /s/ Nickolas J. Lorentzatos, Executive Vice President, General Counsel and Corporate Secretary of OMS Holdings LLC 2022-02-03 /s/ Nickolas J. Lorentzatos, Executive Vice President, General Counsel and Corporate Secretary of Oasis Investment Holdings LLC 2022-02-03 /s/ Nickolas J. Lorentzatos, Executive Vice President, General Counsel and Corporate Secretary of Oasis Petroleum North America LLC 2022-02-03