SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

SCHEDULE 13G

(Rule 13d-102)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO

RULES 13d-1(b), (c) AND (d) AND AMENDMENTS THERETO FILED

PURSUANT TO RULE 13d-2(b)

Double Eagle Petroleum Co.

(Name of Issuer)

Common Stock, par value $0.10 per share

(Title of Class of Securities)

258570209

(CUSIP Number)

January 24, 2014

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

¨ Rule 13d-1(b)

x Rule 13d-1(c)

¨ Rule 13d-1(d)

13G

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SCHEDULE 13G

This Schedule 13G (this “Schedule 13G”) relates to shares of Common Stock, par value $0.10 per share (the “Common Stock”), of Double Eagle Petroleum Co., a Maryland corporation (the “Issuer”), and is being filed on behalf of (i) CrossCap Energy SSF, L.P., a Texas limited partnership (“CrossCap Energy”), (ii) CrossCap General Partners, L.P., a Texas limited partnership (“CrossCap General Partners”), as the general partner of CrossCap Energy, (iii) CrossCap Energy QP SSF, L.P., a Texas limited partnership (“CrossCap Energy QP” and, together with CrossCap Energy, the “Funds”), (iv) CrossCap Enhanced GP, L.P., a Texas limited partnership (“CrossCap Enhanced”), as the general partner of CrossCap Energy QP, (v) CrossCap Management, Inc., a Texas corporation (“CCM”), as general partner of CrossCap General Partners and CrossCap Enhanced and (vi) H. Mark Crosswell, an individual, as the president of CCM (the persons mentioned in (i) (ii), (iii), (iv), (v) and (vi) above are referred to as the “Reporting Persons”).

All shares of Common Stock reported in this Schedule 13G are held by the Funds. CrossCap Energy may direct the vote and disposition of the 239,653 shares of Common Stock that it holds directly. CrossCap General Partners serves as the general partner CrossCap Energy and may direct the vote and disposition of the 239,653 shares of Common Stock held by CrossCap Energy. CrossCap Energy QP may direct the vote and disposition of the 608,000 shares of Common Stock that it holds directly. CrossCap Enhanced serves as the general partner CrossCap Energy QP and may direct the vote and disposition of the 608,000 shares of Common Stock held by CrossCap Energy QP. As the general partner of CrossCap General Partners and CrossCap Enhanced, CCM may direct the vote and disposition of the 847,653 shares of Common Stock held by the Funds. As the president of CCM, Mr. Crosswell may direct the vote and disposition of the 847,653 shares of Common Stock held by the Funds.

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If this statement is filed pursuant to Rule 13d-1(b), or 13d-2(b), check whether the person filing is a:

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CrossCap General Partners is the beneficial owner of 239,653 shares of Common Stock held by CrossCap Energy. CrossCap Enhanced is the beneficial owner of 608,000 shares of Common Stock held by CrossCap Energy QP.

CCM and Mr. Crosswell are the beneficial owners of 847,653 shares of Common Stock held by the Funds.

CrossCap General Partners is the beneficial owner of 2.1% of the outstanding shares of Common Stock. CrossCap Enhanced is the beneficial owner of 5.4% of the outstanding shares of Common Stock.

CCM and Mr. Crosswell are the beneficial owners of 7.5% of the outstanding shares of Common Stock.

These percentages are determined by dividing the number of shares of Common Stock beneficially owned by each of the Reporting Persons by 11,351,412, the number of shares of Common Stock issued and outstanding as of November 1, 2013, as reported in the Issuer’s most recent Form 10-Q filed on November 7, 2013.

CrossCap General Partners, as the general partner of CrossCap Energy, may direct the vote and disposition of the 239,653 shares of Common Stock held by CrossCap Energy. CrossCap Enhanced, as the general partner of CrossCap Energy QP, may direct the vote and disposition of the 608,000 shares of Common Stock held by CrossCap Energy QP.

CCM, as the general partner of CrossCap General Partners and CrossCap Enhanced, may direct the vote and disposition the 847,653 shares of Common Stock held by the Funds. As the president of CCM, Mr. Crosswell may direct the vote and disposition of the 847,653 shares of Common Stock held by the Funds.

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Inapplicable.

Inapplicable.

Inapplicable.

Inapplicable.

Inapplicable.

By signing below each of the Reporting Persons certifies that, to the best of such person’s knowledge and belief, the securities referred to above were acquired and held in the ordinary course of business and were not acquired and were not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

Joint Filing Agreement dated January 28, 2014, by and among CrossCap Energy, CrossCap General Partners, CrossCap Energy QP, CrossCap Enhanced, CCM and Mr. Crosswell.

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SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Date: January 28, 2014

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EXHIBIT 99.1

JOINT FILING AGREEMENT

In accordance with Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended, the undersigned agree to the joint filing on behalf of each of them of a Statement on Schedule 13G (including any and all amendments thereto) with respect to the Common Stock, par value $0.10 per share, of Double Eagle Petroleum Co., a Maryland corporation, and further agree that this Joint Filing Agreement shall be included as an Exhibit to such joint filings.

The undersigned further agree that each party hereto is responsible for the timely filing of such Statement on Schedule 13G and any amendments thereto, and for the accuracy and completeness of the information concerning such party contained therein; provided, however, that no party is responsible for the accuracy or completeness of the information concerning any other party, unless such party knows or has reason to believe that such information is inaccurate.

This Joint Filing Agreement may be signed in counterparts with the same effect as if the signature on each counterpart were upon the same instrument.

IN WITNESS WHEREOF, the undersigned have executed this Agreement as of January 28, 2014.

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