MEMBERSHIP INTEREST PURCHASE AGREEMENT

Exhibit 2.2

MEMBERSHIP INTEREST PURCHASE AGREEMENT

THIS MEMBERSHIP INTEREST PURCHASE AGREEMENT (this “Agreement”) is made and entered into as of the 30^th day of June, 2005, by and among GLEN L. McALISTER, an individual (the “Seller”) and BRONCO DRILLING COMPANY, L.L.C., an Oklahoma limited liability company (“Buyer”).

WITNESSETH:

WHEREAS, the Seller presently owns forty-four percent (44%) of the issued and outstanding membership interests and units in STRATA DRILLING, L.L.C., an Oklahoma limited liability company (“Drilling”), and STRATA PROPERTY, L.L.C., an Oklahoma limited liability company (“Property”, with “Drilling” being collectively referred to as the “Companies”); and

WHEREAS, the Buyer desires to purchase from the Seller, and the Seller desires to sell to the Buyer, all of the Seller’s membership interests and units in the Companies, subject to the terms and conditions described in this Agreement.

NOW, THEREFORE, in consideration of the mutual covenants and agreements described in this Agreement, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the Buyer and the Seller hereby agree as follows:

1. SALE OF MEMBERSHIP INTERESTS. Subject to the terms and conditions of this Agreement, the Seller agrees to sell to the Buyer, and the Buyer agrees to purchase from the Seller, all of the Seller’s membership interests and units in: (i) Drilling, which represents forty-four percent (44%) of the issued and outstanding membership interests and units in Drilling (collectively, the “Drilling Units”); and (ii) Property, which represents forty-four percent (44%) of the issued and outstanding membership interests and units in Property (collectively, the “Property Units”, with the Drilling Units being collectively referred to as the “Membership Interests”), together with any and all rights, privileges and interests in the Companies resulting from, associated with or arising from the Membership Interests.

2. PURCHASE OF RESTRICTED INTERESTS. The Buyer understands that the Membership Interests are being sold to the Buyer under an exemption from registration provided by the Securities Act of 1933, as amended (the “Act”), and by applicable state securities acts, and warrants and represents to the Seller that the Membership Interests being acquired by the Buyer are solely for its own account for investment purposes only, and are not being purchased with a view to, or for the resale, distribution, subdivision or fractionalization thereof, and that the Buyer must bear the economics associated with the Membership Interests for an indefinite period of time because the Membership Interests cannot be resold or otherwise transferred unless subsequently registered under the Act, or unless an exemption from registration is available. Further, the Buyer acknowledges and understands that any certificate that may be issued to the Buyer evidencing the Membership Interests will bear substantially the following legend:

The units represented by this Certificate have not been registered under the United States Securities Act of 1933 (the “Act”) or registered or qualified under any state securities laws and are “restricted securities” as that term is defined in Rule 144 under the Act. The

units may not be offered for sale, sold or otherwise transferred except pursuant to an effective registration statement under the Act, or pursuant to an exemption from registration under the Act or state securities laws, or pursuant to an exemption from registration under the Act, the availability of which is to be established to the satisfaction of the Company. In addition, the rights and obligations of the holder of this Certificate, and the ability of the holder to transfer the units represented by this Certificate, are subject to the approval of the Members of the Company and other restrictions, terms and conditions of the Amended and Restated Operating Agreement of the Company, a copy of which can be obtained from the Company upon written request.

3. CONSIDERATION. The aggregate purchase price to be paid by the Buyer for the Membership Interests at Closing shall be Three Million Two Hundred Sixty-five Thousand and No/100 Dollars ($3,265,000.00), which amount shall be paid to the Seller in cash or certified funds (the “Purchase Price”).

3.1 Real Estate. In connection with and as consideration for the sale of the Membership Interests, Seller shall cause Advanced Investments, L.L.C. (“Investments”) to sell, transfer and convey to Buyer, that certain real property and improvements situated thereon located in Oklahoma County, Oklahoma owned by Investments and more particularly described in Exhibit “B” attached hereto (the “Real Property”), subject to the terms and conditions described in that certain Real Estate Purchase Agreement dated even date herewith by and between Buyer and Investments attached hereto as Exhibit “C” (the “REPA”). The execution and delivery of the REPA by Investments shall be a condition to and a requirement of the execution and delivery of this Agreement by the Seller.

4. REPRESENTATIONS AND WARRANTIES OF SELLER. The Seller hereby represents and warrants to Buyer that the following statements are true and correct as of the date of this Agreement and will be true and correct as of the Closing Date (as hereafter defined).

4.1 Authority; Capacity. The Seller has full power, authority and capacity to execute and deliver, and to perform his duties and obligations under this Agreement. This Agreement is the legal, valid and binding obligation of the Seller and is enforceable against the Seller in accordance with its terms, except as enforceability may be limited by bankruptcy, insolvency, or other similar laws affecting the enforcement of creditors’ rights generally and except that the availability of equitable remedies, including specific performance, may be subject to the discretion of the court before which any proceeding may be brought.

4.2 No Conflicts; Consents. The execution and delivery of this Agreement and the consummation of the transactions contemplated hereby will not: (i) violate or conflict with any constitution, statute, regulation, rule, injunction, judgment, order, permit, decree, ruling, charge, or other restriction of any government, governmental agency, court or arbitrator to which the Seller or any of his assets are subject; (ii) conflict with, result in a breach of, constitute a default under (or with notice or the lapse of time or both could result in a breach of or constitute a default), result in the acceleration of, create in any party the right to accelerate, terminate, modify, or cancel, or require any

-2-

notice or consent under any agreement, contract, lease, license, instrument, or other arrangement to which the Seller is a party or bound or to which any of his assets are subject; (iii) that could result in the creation or imposition of any lien, security interest or encumbrance in, to or on the Membership Interests or any asset of the Seller; or (iv) require the Seller to give any notice to, make any filing with, or obtain any authorization, consent, or approval of any government or governmental agency, creditor or other third party in order to consummate the transactions contemplated by this Agreement, except as required in the Companies’ respective operating agreements.

4.3 Litigation. There are no claims, demands, filings, hearings, notices of violation, proceedings, notices or demand letters, investigations, administrative proceedings, civil, criminal or other actions, litigation, suits, mediations, arbitrations or other legal proceedings pending or threatened against the Seller relating to, resulting from or affecting the Membership Interests or that would materially impair the ability of the Seller to perform his duties or obligations under, or to consummate the transactions contemplated by, this Agreement.

4.4 Title. Except for the outstanding security interest in favor of the members from which the Seller purchased the McAlister Interests, the Seller is the lawful owner of, and has good and marketable title to, the Membership Interests, free and clear of any and all liens, restrictions, claims, charges, security interests and encumbrances (contractual or otherwise) of any kind, nature or type whatsoever. Investments is the lawful owner of, and has good and marketable title to, the Real Property, free and clear of all liens, restrictions, claims, charges, security interests and encumbrances (contractual or otherwise) of any kind, nature or type whatsoever.

4.5 Taxes. The Seller has duly and timely filed all tax returns and reports required to be filed by the Seller prior to the date of this Agreement and Investments has duly and timely filed all tax returns and reports required to be filed by Investments related to or involving the Real Property prior to the date of the REPA (collectively, the “Returns”) and has duly and timely paid all taxes that have been incurred or are due and payable pursuant to such Returns or pursuant to any assessment with respect to taxes in such jurisdictions, whether or not in connection with such Returns. No deficiency or proposed adjustment which has not been settled or otherwise resolved for any amount of tax has been proposed, asserted or assessed by any taxing authority against the Seller or Investments. There are no actions, suits, taxing authority proceedings, or audits now in progress, pending or threatened against the Seller or Investments, and there are no liens for taxes (other than for current taxes not yet due and payable) against the Seller or Investments.

4.6 Membership Interest. The Membership Interests being purchased by the Buyer under this Agreement respectively represent forty-four (44%) of the issued and outstanding membership interests and units in the Companies.

4.8 No Pending Transactions. Except for this Agreement, the Seller is not a party to or bound by any agreement, undertaking or commitment to sell, lease, assign, transfer or exchange any of the Membership Interests to any other entity or person.

-3-

4.9 Full Disclosure. No representation or warranty of the Seller in this Agreement or any agreement, document or scheduled executed or delivered in connection with this Agreement contains any untrue statement of a material fact or omits to state any material fact which makes any such representation or warranty misleading.

4.10 Acknowledgement. Seller understands and acknowledges that Buyer is in negotiations with the holders of the other membership interests in Drilling and Property to purchase their interests and that the terms of such purchases, if agreed to, may differ from the terms contained herein, and that such differences may be material.

5. REPRESENTATIONS AND WARRANTIES OF BUYER. The Buyer hereby represents and warrants to the Seller that the following statements are true and correct as of the date of this Agreement and will be true and correct as of the Closing Date.

5.1 Organization. The Buyer is duly organized, validly existing and in good standing under the laws of the State of Oklahoma, and is duly registered or qualified to do business, and are in good standing, in each jurisdiction in which the nature of its business or properties requires such registration or qualification, except where the failure to so register or qualify would have a material adverse effect.

5.2 Authority; Capacity. The Buyer has full power and authority to execute and deliver, and to perform its duties and obligations under, this Agreement. The execution and delivery of, the performance of its obligations under, and the consummation of the transactions contemplated by, this Agreement and any agreement, document, instrument or certificate executed or to be executed in connection with this Agreement, have been duly authorized by all necessary action on the part of the Buyer. This Agreement is the legal, valid and binding obligation of the Buyer and is enforceable against the Buyer in accordance with its terms, except as enforceability may be limited by bankruptcy, insolvency, or other similar laws affecting the enforcement of creditors’ rights generally and except that the availability of equitable remedies, including specific performance, may be subject to the discretion of the court before which any proceeding may be brought.

5.3 No Conflicts; Consents. Except as contemplated by the Buyer’s loan agreements, the execution and delivery of this Agreement and the consummation of the transactions contemplated hereby will not: (i) violate or conflict with any provision of the organizational documents, as amended, of the Buyer; (ii) violate or conflict with any constitution, statute, regulation, rule, injunction, judgment, order, permit, decree, ruling, charge, or other restriction of any government, governmental agency, court or arbitrator to which the Buyer or any of its assets are subject; (iii) conflict with, result in a breach of, constitute a default under (or with notice or the lapse of time or both could result in a breach of or constitute a default), result in the acceleration of, create in any party the right to accelerate, terminate, modify, or cancel, or require any notice or consent under any agreement, contract, lease, license, instrument, or other arrangement to which the Buyer is a party or bound or to which any of its assets are subject; (iv) result in or require the creation or imposition of any lien, security interest or encumbrance in, to or on any of the properties of the Buyer; or (v) require the Buyer to give any notice to, make any filing

-4-

with, or obtain any authorization, consent, or approval of any government or governmental agency, creditor or other third party in order to consummate the transactions contemplated by this Agreement.

&n