X0306 4 2018-06-11 0 0001486159 Oasis Petroleum Inc. OAS 0001366397 ENCAP ENERGY CAPITAL FUND VI L P C/O ENCAP INVESTMENTS L.P. 1100 LOUISIANA STREET, SUITE 4900 HOUSTON TX 77002 0 0 1 0 0001494333 EnCap VI-B Acquisitions, L.P. C/O ENCAP INVESTMENTS L.P. 1100 LOUISIANA STREET, SUITE 4900 HOUSTON TX 77002 0 0 1 0 0001422885 ENCAP ENERGY CAPITAL FUND VII LP C/O ENCAP INVESTMENTS L.P. 1100 LOUISIANA STREET, SUITE 4900 HOUSTON TX 77002 0 0 1 0 0001504103 EnCap Energy Capital Fund VIII, L.P. C/O ENCAP INVESTMENTS L.P. 1100 LOUISIANA STREET, SUITE 4900 HOUSTON TX 77002 0 0 1 0 0001537403 EnCap Energy Capital Fund VIII Co-Investors, L.P. C/O ENCAP INVESTMENTS L.P. 1100 LOUISIANA STREET, SUITE 4900 HOUSTON TX 77002 0 0 1 0 0001726182 EnCap Partners GP, LLC C/O ENCAP INVESTMENTS L.P. 1100 LOUISIANA STREET, SUITE 4900 HOUSTON TX 77002 0 0 1 0 Common Stock 2018-06-11 4 J 0 25821413 0.00 A 33106166 D Pursuant to the company agreement of Forge Energy, LLC ("Forge Energy"), on June 11, 2018, Forge Energy made a distribution of the securities of the issuer to its sole member, Forge Energy Holdings, LLC ("Forge Energy Holdings"). Pursuant to the company agreement of Forge Energy Holdings, on the same date, Forge Energy Holdings made a pro rata distribution of the securities of the issuer to all of its members, of which EnCap Energy Capital Fund VIII, L.P. ("EnCap Fund VIII") and EnCap Energy Capital Fund VIII Co-Investors, L.P. ("EnCap Fund VIII Co-Invest") are members. As a result of the foregoing distributions by Forge Energy and Forge Energy Holdings, EnCap Fund VIII directly owns 18,774,504 shares of common stock of the issuer and EnCap Fund VIII Co-Invest directly owns 7,046,909 shares of common stock of the issuer. As described below, EnCap Fund VIII and EnCap Fund VIII Co-Invest are each under common control with EnCap Energy Capital Fund VI, L.P. ("EnCap Fund VI"), EnCap VI-B Acquisitions, L.P. ("EnCap VI-B") and EnCap Energy Capital Fund VII, L.P. ("EnCap Fund VII" and, together with EnCap Fund VI, EnCap VI-B, EnCap Fund VIII and EnCap Fund VIII Co-Invest, the "EnCap Funds"), The EnCap Funds are controlled indirectly by EnCap Partners GP, LLC ("EnCap Partners GP"). EnCap Partners GP is the general partner of EnCap Partners, LP ("EnCap Partners LP"), which is the sole member of EnCap Investments Holdings, LLC ("EnCap Investments Holdings"), which is the sole member of EnCap Investments Holdings Blocker, LLC ("EnCap Investments Holdings Blocker"), which is the sole member of EnCap Investments GP, L.L.C. ("EnCap Investments GP"), which is the general partner of EnCap Investments L.P. ("EnCap Investments LP"), which is the sole member of each of (i) EnCap Equity Fund VI GP, LLC ("EnCap Fund VI GP LLC"), which is the sole general partner of EnCap Equity Fund VI GP, L.P. ("EnCap Fund VI GP"), (ii) EnCap Equity Fund VII GP, LLC ("EnCap Fund VII GP LLC"), (Continued from footnote 3) which is the sole general partner of EnCap Equity Fund VII GP, L.P. ("EnCap Fund VII GP") and (iii) EnCap Equity Fund VIII GP, LLC ("EnCap Fund VIII GP LLC"), which is the sole general partner of EnCap Equity Fund VIII GP, L.P. ("Equity Fund VIII GP"). EnCap Fund VI GP is the sole general partner of EnCap Fund VI and EnCap Fund VI-B, EnCap Fund VII GP is the sole general partner of EnCap Fund VII and EnCap Fund VIII GP is the sole general partner of each of EnCap Fund VIII and EnCap Fund VIII Co-Invest. Therefore EnCap Partners GP, EnCap Partners LP, EnCap Investments Holdings, EnCap Investments Holdings Blocker, EnCap Investments GP, EnCap Investments LP, EnCap Fund VI GP LLC, EnCap Fund VI GP, EnCap Fund VII GP LLC, EnCap Fund VII GP, EnCap Fund VIII GP LLC and EnCap Fund VIII GP may be deemed to beneficially own the reported securities. The reporting persons disclaim beneficial ownership of the reported securities except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that the reporting persons are the beneficial owners of the reported securities for purposes of Section 16 or for any other purpose. Signed by D. Martin Phillips as a Managing Director of EnCap Partners GP, in its capacity as the general partner of EnCap Partners LP, in its capacity as the sole member of EnCap Investments Holdings, in its capacity as the sole member of EnCap Investments Holdings Blocker, in its capacity as the sole member of EnCap Investments GP, in its capacity as the general partner of EnCap Investments LP, in its capacity as the sole member of each of (i) EnCap Fund VI GP LLC, in its capacity as the sole general partner of EnCap Fund VI GP, in its capacity as the general partner of each of EnCap Fund VI and EnCap Fund VI-B, (ii) EnCap Fund VII GP LLC, in its capacity as the general partner of EnCap Fund VII GP, in its capacity as the general partner of EnCap Fund VII and (iii) EnCap Fund VIII GP LLC, in its capacity as the general partner of EnCap Fund VIII GP, in its capacity as the general partner of each of EnCap Fund VIII and EnCap Fund VIII Co-Invest. /s/ D. Martin Phillips 2018-06-13