ASSIGNMENT OF OVERRIDING ROYALTY (Multiple Assignees)

Exhibit 10.15

NOTICE OF CONFIDENTIALITY RIGHTS: IF YOU ARE A NATURAL PERSON, YOU MAY REMOVE OR STRIKE ANY OF THE FOLLOWING INFORMATION FROM THIS INSTRUMENT BEFORE IT IS FILED FOR RECORD IN THE PUBLIC RECORDS: YOUR SOCIAL SECURITY NUMBER OR YOUR DRIVER’S LICENSE NUMBER.

ASSIGNMENT OF OVERRIDING ROYALTY

(Multiple Assignees)

TDM Holding, LLC whose address is 100 Throckmorton, Ste. 1700, Fort Worth, Texas 76102, hereinafter called “Assignor”, for and inconsideration of the sum of TEN DOLLARS ($10.00) and other good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged by Assignor, does by these presents, GRANT, ASSIGN, TRANSFER and CONVEY unto the parties set forth below, hereinafter called the “Assignees”:

KSJR, LLC, a Texas limited liability company whose address is P.O. Box 68, Kenny, Texas 77452;

Karpman Enterprises, LP, a Texas limited partnership whose address is 2721 Manorwood Trail, Fort Worth, Texas 76109;

CDA Energy, LLC, a Texas limited liability company whose address is 1926 Stafford Rd., Grapevine, Texas 76015;

DLP Resources, LLC, a Texas limited liability company whose address is 3121 Sweetbriar Lane, Fort Worth, Texas 76109;

Alpine Ventures International, LLC, a Texas limited liability company whose address is 4654 Trevor Trail, Grapevine, Texas 76051;

Pettit 2012 Children’s Trust whose address is 2821 Lenox, Fort Worth, Texas 76107;

BHP Consulting LP, a Texas limited partnership whose address is 3821 Lenox, Fort Worth, Texas 76107; and

Brian Corbett Nelson, an individual, whose address is 3090 Bellaire Ranch Dr., Apt. 422, Fort Worth, Texas 76109;

Tom D. McNutt, an individual, whose address is 2000 Bremen St., Austin, 78703;

Charlotte Brandenburg, an individual, whose address is 5324 Big Bend Dr., Fort Worth, Texas 76137;

Carey Hewitt, an individual, whose address is 4509 Ramsgate Ct., Arlington 76013.

an overriding royalty interest (the “Overriding Royalty”), as described in Exhibit “A” attached hereto and made a part hereof for all purposes, in all oil, gas and other hydrocarbons produced, save and sold under the terms of the Oil and Gas Leases described in Exhibit “A” (the “Lease(s)”) covering the lands described therein located in Madison, Grimes and Walker Counties, Texas.

The assignment of Overriding Royalty made herein is subject to the following terms, conditions and provisions:

TO HAVE AND TO HOLD the above described overriding royalty, together with all and singular the rights and appurtenances thereunto in anywise belonging unto Assignee, its successors and assigns forever; and Assignor does by these presents bind itself and its successors and assigns to warrant and forever defend all and singular, the Leases unto Assignee, its successors and assigns, against every person whomsoever lawfully claiming or to claim the same or any part thereof by, through or under Assignor, but not otherwise.

[Signature page follows.]

IN WITNESS WHEREOF, the parties have executed this instrument as of the dates set forth in the acknowledgement certificates below, but it is effective as of the date of each Lease.

~ACKNOWLEDGEMENT~

STATE OF TEXAS

COUNTY OF TARRANT

The foregoing instrument was acknowledged before me on this 20 of August, 2012 by Tom D. McNutt, Manager of TDM Holding, LLC, a Texas limited liability company, on behalf of said company.

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