X0306 4 2018-11-19 0 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 STREET, SUITE 1500 HOUSTON TX 77002 0 0 1 0 0001717320 OMS Holdings LLC 1001 FANNIN STREET, SUITE 1500 HOUSTON TX 77002 0 0 1 0 Common units representing limited partner interests 2018-11-19 4 J 0 3950000 A 9075000 I See Footnotes Subordinated units representing limited partner interests Common units representing limited partner interests 13750000 13750000 I See Footnote Pursuant to that certain Contribution Agreement, by and among Oasis Midstream Partners, LP (the "Issuer"), OMS Holdings LLC ("OMS Holdings"), Oasis Midstream Services LLC, OMP GP LLC, OMP Operating LLC and, for certain limited purposes set forth therein, Oasis Petroleum Inc. ("OAS"), dated November 7, 2018, OAS caused OMS to contribute certain assets to OMP Operating, as the Issuer's designee, in exchange for the distribution to OMS Holdings of consideration including 3,950,000 common units representing limited partner interests ("common units"). The subordinated units representing limited partner interests in the Issuer ("subordinated units") have no expiration date and will convert into common units on a one-for-one basis at the end of the "subordination period" described in the Issuer's Prospectus (File No. 333-217976) filed with the Securities and Exchange Commission on September 22, 2017. This Form 4 is being filed jointly by OMS Holdings, Oasis Petroleum LLC ("Oasis Petroleum") and OAS. As of November 27, 2018, OMS Holdings directly owns 9,075,000 common units and 13,750,000 subordinated units, Oasis Petroleum directly owns 100% of the outstanding membership interests in OMS Holdings and OAS directly owns 100% of the outstanding membership interests in Oasis Petroleum. Accordingly, OAS and Oasis Petroleum may be deemed to be an indirect beneficial owner 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. 2018-11-28 /s/ Nickolas J. Lorentzatos, Executive Vice President, General Counsel and Corporate Secretary of Oasis Petroleum LLC 2018-11-28 /s/ Nickolas J. Lorentzatos, Executive Vice President, General Counsel and Corporate Secretary of OMS Holdings LLC 2018-11-28