13D Filing: Harvest Fund Advisors LLC and BP Midstream Partners LP (BPMP)

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Explanatory Note

The securities reported herein are beneficially owned by Harvest Fund Advisors LLC (HFA), an investment management firm with over
$10 billion in assets under management, which provides investment management services to funds and separately managed accounts. On October 16, 2017, The Blackstone Group L.P. and certain of its affiliates (Blackstone)
acquired HFA. Following that acquisition, Blackstone may now be deemed to be the beneficial owner of the securities beneficially owned by HFA, including the securities reported herein. In connection with the acquisition by Blackstone, HFA will,
along with Blackstone, report its beneficial ownership of such securities on a Schedule 13D.

Item 1.

Security and Issuer.

This Statement on Schedule 13D (this Schedule
13D) relates to common units representing limited partner interests (the Common Units) of BP Midstream Partners LP, a Delaware limited partnership (the Issuer). The principal executive offices of the
Issuer are located at 501 Westlake Park Boulevard, Houston, Texas 77079.

Item 2.

Identity and Background

(a)-(b) Each of the following is hereinafter individually
referred to as a Reporting Person and collectively as the Reporting Persons. This statement is filed on behalf of:

(i)

Harvest Fund Advisors LLC, a Delaware limited liability company (HFA),

(ii)

Harvest Fund Holdco L.P., a Delaware limited partnership,

(iii)

Blackstone Harvest Holdco L.L.C., a Delaware limited liability company,

(iv)

Blackstone Intermediary Holdco L.L.C., a Delaware limited liability company,

(v)

Blackstone Advisory Partners L.P., a Delaware limited partnership,

(vi)

Blackstone Advisory Services L.L.C., a Delaware limited liability company,

(vii)

Blackstone Holdings I L.P., a Delaware limited partnership,

(viii)

Blackstone Holdings I/II GP Inc., a Delaware corporation,

(ix)

The Blackstone Group L.P., a Delaware limited partnership,

(x)

Blackstone Group Management L.L.C., a Delaware limited liability company (each of the entities listed in (ii) through (x), a Blackstone entity), and

(xi)

Stephen A. Schwarzman, a citizen of the United States of America (and collectively with the Blackstone entities, the Blackstone Persons).

The principal business address of HFA is 100 W. Lancaster Avenue, Suite 200, Wayne, PA 19087. The principal business address of each of the
Blackstone Persons is c/o The Blackstone Group L.P., 345 Park Avenue, New York, New York 10154.

(c) HFA is a registered investment
adviser that provides investment management services to funds and separately managed accounts.

The principal business of Harvest Fund
Holdco L.P. is performing the functions of, and serving as, the sole member of HFA. The principal business of Blackstone Harvest Holdco L.L.C. is performing the functions of, and serving as, the general partner of Harvest Fund Holdco L.P. The
principal business of Blackstone Intermediary Holdco L.L.C. is performing the functions of, and serving as, the sole member of Blackstone Harvest Holdco L.L.C. The principal business of Blackstone Advisory Partners L.P. is performing the functions
of, and serving as, the sole member of Blackstone Intermediary Holdco L.L.C. The principal business of Blackstone Advisory Services L.L.C. is performing the functions of, and serving as, the general partner of Blackstone Advisory Partners L.P. The
principal business of Blackstone Holdings I L.P. is performing the function of, and serving as, the sole member (or similar position) of Blackstone Advisory Services L.L.C. and other affiliated Blackstone entities. The principal business of
Blackstone Holdings I/II GP Inc. is performing the functions of, and serving as, the general partner of Blackstone Holdings I L.P. and other affiliated Blackstone entities.

The principal business of The Blackstone Group L.P. is performing the functions of, and serving as, the controlling shareholder of Blackstone
Holdings I/II GP Inc., and in a similar capacity for other affiliated Blackstone

entities. The principal business of Blackstone Group Management L.L.C. is
performing the functions of, and serving as, the general partner of The Blackstone Group L.P.