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

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934*

(Amendment No.    )

BP MIDSTREAM
PARTNERS LP

(Name of Issuer)

Common Units Representing Limited Partner Interests

(Title of Class of Securities)

0556EL109

(CUSIP Number)

Anthony Merhige

Harvest Fund Advisors LLC

100 West Lancaster Avenue, Suite 200

Wayne, Pennsylvania 19087

Tel: (610) 341-9700

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

October 27, 2017

(Date of Event which Requires Filing of this Statement)

If the filing person has
previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e),
240.13d-1(f) or 240.13d-1(g), check the following box: [ ]

NOTE: Schedules filed in paper format shall
include a signed original and five copies of the schedule, including all exhibits. See Rule 240.13d-7 for other parties to whom copies are to be sent.

The information required on the remainder of this cover page shall not be
deemed to be filed for the purpose of Section 18 of the Securities Exchange Act of 1934 (Act) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act
(however, see the Notes).

SCHEDULE 13D

SCHEDULE 13D

SCHEDULE 13D

SCHEDULE 13D

SCHEDULE 13D

SCHEDULE 13D

SCHEDULE 13D

SCHEDULE 13D

SCHEDULE 13D

SCHEDULE 13D

SCHEDULE 13D

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.

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.

(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:

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.

The principal occupation of Mr. Schwarzman is serving as an executive of Blackstone Group
Management L.L.C.

(d) During the last five years, none of the Reporting Persons has been convicted in a criminal proceeding (excluding
traffic violations or similar misdemeanors).

(e) During the last five years, none of the Reporting Persons has been a party to a civil
proceeding of a judicial or administrative body of competent jurisdiction and, as a result of such proceeding, was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to,
federal or state securities laws or finding any violation with respect to such laws.

(f) See Items 2(a)-(b) above for place of
organization or citizenship of each of the Reporting Persons.

The funds and accounts managed by HFA
acquired the securities reported herein for aggregate consideration of approximately $72.2 million, using cash available in such funds and accounts.

HFA acquired the securities reported herein for investment
purposes. The Blackstone Persons may be deemed to be the beneficial owners of the securities acquired by HFA.

The Reporting Persons
intend to review their investment in the Issuer on an ongoing basis and, in the course of their review, may take actions (including through their affiliates) with respect to their investment or the Issuer, including communicating with the board of
directors of the general partner of the Issuer (the Board), members of management and/or other securityholders of the Issuer or other third parties from time to time, taking steps to implement a course of action, including,
without limitation, engaging advisors, including legal, financial, regulatory, technical and/or industry advisors, to assist in any review, and evaluating strategic alternatives as they may become available. Such discussions and other actions may
relate to various alternative courses of action, including, without limitation, those related to an extraordinary corporate transaction (including, but not limited to a merger, reorganization or liquidation) involving the Issuer or any of its
subsidiaries; business combinations involving the Issuer or its subsidiaries, a sale or transfer of a material amount of assets of the Issuer or any of its subsidiaries; material asset purchases; the formation of joint ventures with the Issuer or
its subsidiaries or the entry into other material projects; changes in the present business, operations, strategy, future plans or prospects of the Issuer, financial or governance matters; changes to the Board (including Board composition) or
management of the Issuer; acting as a participant in debt financings of the Issuer or its subsidiaries, changes to the capitalization, ownership structure, dividend policy, business or corporate structure or governance documents of the Issuer; de-listing or de-registration of the Issuers securities, or any action similar to those enumerated above. Such discussions and actions may be preliminary and exploratory
in nature, and not rise to the level of a plan or proposal. The Reporting Persons or their affiliates may seek to acquire securities of the Issuer, including Common Units and/or other equity, debt, notes, or other financial instruments related to
the Issuer or the Common Units (which may include rights or securities exercisable or convertible into securities of the Issuer), and/or sell or otherwise dispose of some or all of such Issuer securities or financial instruments (which may include
distributing some or all of such securities to such Reporting Persons respective partners or beneficiaries, as applicable) from time to time, in each case, in open market or private transactions, block sales or otherwise. Any transaction that
any of the Reporting Persons or their affiliates may pursue may be made at any time and from time to time without prior notice and will depend on a variety of factors, including, without limitation, the price and availability of the Issuers
securities or other financial instruments, the Reporting Persons or such affiliates trading and investment strategies, subsequent developments affecting the Issuer, the Issuers business and the Issuers prospects, other
investment and business opportunities available to such Reporting Persons and their affiliates, general industry and economic conditions, the securities markets in general, tax considerations and other factors deemed relevant by such Reporting
Persons and their affiliates.

Except as described in this Schedule 13D, the Reporting Persons do not have any present plans or proposals
that relate to or would result in any of the actions described in subparagraphs (a) through (j) of Item 4 of Schedule 13D, although, such persons, at any time and from time to time, may review, reconsider and change their position and/or change
their purpose and/or develop such plans and may seek to influence management or the Board with respect to the business and affairs of the Issuer and may from time to time consider pursuing or proposing such matters with advisors, the Issuer or other
persons.

(a) and (b). Calculations of the percentage of
Common Units beneficially owned assumes that there are a total of 46,000,535 Common Units outstanding as of October 30, 2017 (excluding the 6,375,000 Common Units underlying the underwriters option in connection with the Issuers initial
public offering), based on information in the Issuers prospectus on Form 424B4 filed on October 27, 2017. Upon the underwriters exercise of their option to acquire an additional 6,375,000 Common Units (or if such option is not
exercised, upon the issuance of such Common Units to an affiliate of the Issuer), the number of Common Units beneficially owned as reported herein would equal approximately 7.7% of the outstanding Common Units.

The aggregate number and percentage of Common Units beneficially owned by each Reporting Person and, for each Reporting Person, the number of
Common Units as to which there is sole power to vote or to direct the vote, shared power to vote or to direct the vote, sole power to dispose or to direct the disposition, or shared power to dispose or to direct the disposition are set forth on rows
7 through 11 and row 13 of the cover pages of this Schedule 13D and are incorporated herein by reference.

The amounts reported herein
reflect the number of Common Units held by funds and accounts managed by HFA as ofNovember 1, 2017. None of the Blackstone Persons directly owns any Common Units.

Harvest Fund Holdco L.P. is the sole member of HFA. Blackstone Harvest Holdco L.L.C. is the general partner of Harvest Fund Holdco L.P.
Blackstone Intermediary Holdco L.L.C. is the sole member of Blackstone Harvest Holdco L.L.C. Blackstone Advisory Partners L.P. is the sole member of Blackstone Intermediary Holdco L.L.C. Blackstone Advisory Services L.L.C. is the general partner of
Blackstone Advisory Partners L.P. Blackstone Holdings I L.P. is the sole member of Blackstone Advisory Services L.L.C. Blackstone Holdings I/II GP Inc. is the general partner of Blackstone Holdings I L.P. The Blackstone Group L.P. is the controlling
shareholder of Blackstone Holdings I/II GP Inc. The general partner of The Blackstone Group L.P. is Blackstone Group Management L.L.C. Blackstone Group Management L.L.C. is wholly-owned by Blackstones senior managing directors and controlled
by its founder, Stephen A. Schwarzman.

HFA, an investment adviser registered under the Investment Advisers Act of 1940, as amended,
advises funds and accounts. In such capacity, HFA has voting authority and dispositive discretion over the securities of the Issuer described in this Schedule 13D that are owned by the funds and accounts advised by it. Except for the purpose of
determining beneficial ownership under Section 13(d) of the Securities Exchange Act of 1934, as amended (the Exchange Act), HFA and the other Reporting Persons each disclaims beneficial ownership of all securities reported as
beneficially owned by HFA in this Schedule 13D. None of the Reporting Persons has any pecuniary interest in the securities reported as beneficially owned by HFA in this Schedule 13D, as such term is used for purposes of Section 16 of the
Exchange Act. Neither the filing of this Schedule 13D nor any of its contents shall be deemed to constitute an admission that any of the Reporting Persons is the beneficial owner of the securities referred to herein for purposes of
Section 13(d) or Section 16 of the Exchange Act or for any other purpose.

(c) Except as set forth in Schedule 1 of this
Schedule 13D, none of the Reporting Persons has effected any transaction in the past 60 days in Common Units.

(d) To the best knowledge
of the Reporting Persons, no person other than the Reporting Persons (or the funds or accounts managed by HFA) has the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the securities
beneficially owned by the Reporting Persons identified in this Item 5.

(e) Not applicable.

An account managed by HFA has entered into notional principal amount derivative agreements (the Derivative Agreements) in
the form of cash settled swaps with respect to 1,000,000 Common Units (representing economic exposure to approximately 2.2% of the Common Units). The Derivative Agreements provide such holder with economic results that are comparable to the economic
results of ownership but do not provide it with the power to vote or direct the voting or dispose of or direct the disposition of the Common Units that are the subject of the Derivative Agreements (such units, the Subject Units).
The Reporting Persons disclaim beneficial ownership in the Subject Units. The counterparties to the Derivative Agreements are unaffiliated third party financial institutions.

Exhibit A     Joint Filing Agreement by
and among the Reporting Persons (filed herewith).

SIGNATURES

After reasonable inquiry and to the best of its or his knowledge and belief, each of the undersigned certifies that the information set forth
in this statement is true, complete and correct.

Dated: November 6, 2017

[BP Midstream Partners LP
Schedule 13D]

[BP Midstream Partners LP
Schedule 13D]

SCHEDULE 1

The below reflects the transactions in Common Units effected by the Reporting Persons during the past 60 days. Except as otherwise set forth below, all
transactions occurred in the open market.