Exhibit 5.1

            , 2014

FORM OF OPINION

Mammoth Energy Partners LP

4727 Gaillardia Parkway, Suite 200

Oklahoma City, OK 73142

Registration Statement on Form S-1

(File No. 333-198894)

Ladies and Gentlemen:

We have acted as special counsel to Mammoth Energy Partners LP, a Delaware limited partnership (the “Partnership”), in connection with the preparation and filing by the Partnership with the Securities and Exchange Commission (the “Commission”) of a Registration Statement on Form S-1, as amended (File No. 333-198894) (the “Registration Statement”), under the Securities Act of 1933, as amended (the “Act”). The Registration Statement relates to an underwritten public offering by the Partnership of up to             common units (including up to             common units subject to the Underwriters’ (as defined below) overallotment option) (the “Primary Units”) representing limited partner interests in the Partnership (“Common Units”) and up to             Common Units (including up to             Common Units subject to the Underwriters’ overallotment option) (the “Secondary Units”) to be sold by the selling unitholders listed in the Registration Statement (the “Selling Unitholders”) pursuant to the terms of an underwriting agreement (the “Underwriting Agreement”) to be executed by the Partnership, Mammoth Energy Partners GP LLC, the Selling Unitholders, and Credit Suisse Securities (USA) LLC, as representative of the underwriters named therein (the “Underwriters”). This opinion is being furnished in accordance with the requirements of Item 601(b)(5) of Regulation S-K under the Act.

We have examined originals or certified copies of such partnership records of the Partnership and other certificates and documents of officials of the Partnership or its general partner, public officials and others as we have deemed appropriate for purposes of this letter. We have assumed the genuineness of all signatures, the legal capacity of all natural persons, the authenticity of all documents submitted to us as originals and the conformity to authentic original documents of all copies submitted to us as conformed, certified or reproduced copies. We have also assumed that, upon sale and delivery, the certificates for the Primary Units, if certificated, will conform to the specimen thereof included as an exhibit to the partnership agreement of the Partnership filed as an exhibit to the Registration Statement and will have been duly

Mammoth Energy Partners LP

            , 2014

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countersigned by the transfer agent and duly registered by the registrar for the Common Units or, if uncertificated, valid book-entry notations for the issuance of the Primary Units in uncertificated form will have been duly made in the register of Common Units of the Partnership. As to various questions of fact relevant to this letter, we have relied, without independent investigation, upon certificates of public officials and certificates of officers of the general partner of the Partnership, all of which we assume to be true, correct and complete.

Based upon the foregoing, and subject to the assumptions, exceptions, qualifications and limitations stated herein, we are of the opinion that (i) when the Underwriting Agreement has been duly executed and delivered and the Primary Units have been issued and delivered in accordance with the Underwriting Agreement against payment in full of the consideration payable therefor as determined in accordance with the partnership agreement of the Partnership by the Board of Directors of the general partner of the Partnership or a duly authorized committee thereof and as contemplated by the Underwriting Agreement, the Primary Units will have been duly authorized and validly issued, and holders of the Primary Units will have no obligation to make any further payments to the Partnership for the issuance of the Primary Units or contributions to the Partnership solely by reason of their ownership of the Primary Units and (ii) the Secondary Units are duly authorized and validly issued, and holders of the Secondary Units have no obligation to make any further payments to the Partnership for the issuance of the Secondary Units or contributions to the Partnership solely by reason of their ownership of the Secondary Units.

The opinions and other matters in this letter are qualified in their entirety and subject to the following:

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and to the use of our name in the Prospectus forming a part of the Registration Statement under the caption “Legal Matters.” In giving this consent, we do not thereby admit that we are within the category of persons whose consent is required under Section 7 of the Act and the rules and regulations thereunder.

Mammoth Energy Partners LP

            , 2014

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