EX-5.1

Exhibit 5.1

1000 Main Street, 36th Floor
Houston, Texas 77002-6341

(713) 226-6000 Main

porterhedges.com

November 22, 2021

U.S. Well Services, Inc.

1360 Post Oak Boulevard, Suite 1800

Houston, Texas 77056

Ladies and Gentlemen:

We have acted as special counsel to U.S. Well Services, Inc., a Delaware corporation (the “Company”), in connection with the registration under the Securities Act of 1933, as amended (the “Securities Act”), on a registration statement on Form S-3, as may be amended from time to time (the “Registration Statement”), filed with the Securities and Exchange Commission (the “SEC”), for the offer and sale by the selling stockholders named in the Registration Statement, of (i) 6,055,367 shares (the “Common Shares”) of the Company’s Class A common stock, par value $0.0001 per share (the “Common Stock”), and (ii) up to 27,682,239 shares (the “Conversion Shares”) of Common Stock, issuable upon conversion of the Company’s 16.0% Convertible Senior Secured (Third Lien) PIK Notes (the “Convertible Notes”), that were issued pursuant to the Note Purchase Agreement, dated as June 24, 2021, by and among the Company and the purchasers party thereto (as amended, the “Note Purchase Agreement”).

As the basis for the opinions hereinafter expressed, we have examined: (i) originals, or copies certified or otherwise identified, of (a) the Registration Statement; (b) the Second Amended and Restated Certificate of Incorporation of the Company, as amended to date; (c) the Amended and Restated Bylaws of the Company, as amended to date; (d) the Note Purchase Agreement, including the form of Convertible Notes contained in the Note Purchase Agreement, (e) certain resolutions of the Board of Directors of the Company; (f) such other instruments and documents as we have deemed necessary or advisable for the purposes of this opinion; and (g) such other documents, corporate records, certificates of officers of the Company and of public officials and other instruments as we have deemed necessary or advisable to enable us to render these opinions; and (ii) such statutes, including the General Corporation Law of the State of Delaware, and regulations as we have deemed necessary or advisable for the purposes of this opinion. We have not independently verified any factual matter relating to this opinion.

In making our examination, we have assumed and have not verified (i) that all signatures on documents examined by us are genuine, (ii) the legal capacity of all natural persons, (iii) the authenticity of all documents submitted to us as originals and (iv) the conformity to the original documents of all documents submitted to us as copies thereof.

Based on the foregoing, and subject to the assumptions, exceptions and qualifications set forth herein, we are of the opinion that (i) the Common Shares have been validly issued and are fully paid and non-assessable, and (ii) when the Conversion Shares have been duly delivered upon conversion of a Convertible Note, in accordance with the terms of the Note Purchase