13D Filing: Oasis Petroleum Inc. and Oasis Midstream Partners LP (OMP)

The General Partners Limited Liability Company Agreement

Under the Amended and Restated Limited Liability Company Agreement of the General Partner (the GP LLC Agreement), OMS Holdings has
the right to elect the members of the board of directors of the General Partner.

To the Reporting Persons knowledge, there are no
other contracts, arrangements, understandings or relationships (legal or otherwise) among the persons named in Item 2 and between such persons and any person with respect to any securities of the Issuer.

References to, and descriptions of, the Partnership Agreement as set forth in this Item 6 are qualified in their entirety by reference to the
Partnership Agreement filed as Exhibit 3.1 to the Issuers current report on Form 8-K filed with the Commission on September 29, 2017, which is incorporated in its entirety in this Item 6. References
to, and descriptions of, the GP LLC Agreement as set forth in this Item 6 are qualified in their entirety by reference to the GP LLC Agreement filed as Exhibit 3.6 to the Issuers Registration Statement (Registration No. 333-217976), initially filed with the Commission on May 12, 2017, which is incorporated in its entirety in this Item 6.

Registration Rights Agreement

In
connection with the registration rights agreement by and among the Issuer and OMS Holdings (the Registration Rights Agreement), dated September 25, 2017, the Issuer may be required to register the sale of the (i) common units
issued (or issuable) to OMS Holdings pursuant to the Contribution Agreement, (ii) subordinated units and (iii) common units issuable upon conversion of subordinated units pursuant to the terms of the Partnership Agreement (collectively,
the Registrable Securities) it holds. Under the Registration Rights Agreement, OAS has the right to request that the Issuer register the sale of Registrable Securities held by OMS Holdings, and OMS Holdings will have the right to require
the Issuer to make available shelf registration statements permitting sales of Registrable Securities into the market from time to time over an extended period, subject to certain limitations. Pursuant to the Registration Rights Agreement and the
Partnership Agreement, the Issuer may be required to undertake a future public or private offering and use the proceeds (net of underwriting or placement agency discounts, fees and commissions, as applicable) to redeem an equal number of common
units from OMS Holdings. In addition, the Registration Rights Agreement gives OMS Holdings piggyback registration rights under certain circumstances. The Registration Rights Agreement also includes provisions dealing with indemnification
and contribution and allocation of expenses. All of the Registrable Securities held by OMS Holdings and any permitted transferee will be entitled to these registration rights.

The Underwriting Agreement

In connection
with the Underwriting Agreement, by and among the Issuer, the General Partner and Morgan Stanley & Co. LLC and the other underwriters named therein, dated September 20, 2017, relating to the Offering (the Underwriting
Agreement), OMS Holdings, certain of its affiliates and the executive officers and directors of the General Partner have agreed not to sell any common units they beneficially own for a period of 180 days from the date of the Underwriting
Agreement. References to, and descriptions of, the Underwriting Agreement as set forth in this Item 6 are qualified in their entirety by reference to the Underwriting Agreement filed as Exhibit 1.1 to the Issuers current report on Form 8-K filed with the Commission on September 22, 2017, which is incorporated in its entirety in this Item 6.

Item 7. Material to Be Filed as Exhibits