Assignment and Assumption Agreement by and among DCRD, NewCo, CST and Computershare, dated February 21, 2023

Exhibit 4.1

WARRANT ASSIGNMENT AND ASSUMPTION AGREEMENT

HAMMERHEAD ENERGY INC.,

DECARBONIZATION PLUS ACQUISITION CORPORATION IV,

CONTINENTAL STOCK TRANSFER & TRUST COMPANY,

COMPUTERSHARE INC.

and

COMPUTERSHARE TRUST COMPANY, N.A.

Dated February 21, 2023

This Assignment and Assumption Agreement (the “Agreement”) is entered into as of February 21, 2023 (the “Effective Date”), by and among Decarbonization Plus Acquisition IV Corporation, an Alberta corporation (“DCRD”), Hammerhead Energy Inc., an Alberta corporation (“NewCo”), Continental Stock Transfer & Trust Company, a New York corporation (“Continental”) and Computershare Inc., a Delaware corporation, and its affiliate, Computershare Trust Company, N.A., a federally chartered trust company (collectively, “Computershare”). Capitalized terms used but not otherwise defined herein shall have the meanings given to such terms in the Business Combination Agreement (as defined below).

WHEREAS, DCRD and Continental have previously entered into the SPAC Warrant Agreement governing the terms of the SPAC Warrants;

WHEREAS, DCRD previously transferred by way of continuation from the Cayman Islands to Alberta in accordance with the Cayman Islands Companies Act (as amended) and domesticated as an Alberta corporation in accordance with the applicable provisions of the Business Corporations Act (Alberta);

WHEREAS, pursuant to the Business Combination Agreement, dated as of September 25, 2022 (as may be amended from time to time, the “Business Combination Agreement”), by and among DCRD, Hammerhead Resources Inc., an Alberta corporation, NewCo, and ###-###-#### Alberta ULC, an Alberta unlimited liability corporation, the parties intend to consummate a business combination, pursuant to which, among other things, DCRD will amalgamate with NewCo on or about the date hereof (the “SPAC Amalgamation”) and form one corporate entity (”New SPAC”);

WHEREAS, in connection with the SPAC Amalgamation and pursuant to the Business Combination Agreement, each SPAC Warrant, including (a) 15,812,000 warrants sold to the public in DCRD’s initial public offering (the “DCRD IPO” and such warrants, the “DCRD Public Warrants”) and (b) 12,737,500 warrants issued to Decarbonization Plus Acquisition Sponsor IV LLC, a Cayman Islands limited liability company (“DCRD Sponsor”), and certain of DCRD’s independent directors in connection with the DCRD IPO (the “DCRD Private Placement Warrants”), will be exchanged for warrants to purchase an equal number of Class A common

shares in the authorized share capital of New SPAC (“New SPAC Class A Common Shares”) (as exchanged, such DCRD Public Warrants being referred to as “Public Warrants,” such DCRD Private Placement Warrants being referred to as “Private Placement Warrants” and such SPAC Warrants being referred to as “Warrants”) and be governed by the Amended and Restated Warrant Agreement to be entered into on or about the date hereof by New SPAC and Computershare (the “Amended and Restated Warrant Agreement”);

WHEREAS, in connection with the foregoing, DCRD, NewCo, Continental and Computershare wish that (i) New SPAC shall assume by way of assignment and assumption all of the liabilities, duties and obligations of DCRD under and in respect of the SPAC Warrant Agreement, (ii) Computershare shall be appointed as successor warrant agent under the SPAC Warrant Agreement and (iii) DCRD and the Continental shall be released from all liabilities, duties and obligations under and in respect of the SPAC Warrant Agreement; and

WHEREAS, Continental consents to the assignment and assumption of the SPAC Warrant Agreement from DCRD to New SPAC and wishes to release DCRD from its liabilities, duties and obligations under and in respect of the SPAC Warrant Agreement and DCRD consents to the assignment and assumption of the SPAC Warrant Agreement from Continental to Computershare and wishes to release Continental from its liabilities, duties and obligations under and in respect of the SPAC Warrant Agreement.

NOW, THEREFORE, the parties hereby agree as follows:

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IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be duly executed as of the date first above written.

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