UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d)

OF THE SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported): July 24, 2014

QR Energy, LP

(Exact name of registrant as specified in its charter)

5 Houston Center

1401 McKinney Street, Suite 2400

Houston, Texas 77010

(Address of principal executive office) (Zip Code)

(713) 452-2200

(Registrants’ telephone number, including area code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

On July 24, 2014, QR Energy, LP, a Delaware limited partnership (the “Partnership” or “QR Energy”), issued a press release announcing its financial results for the six months ended June 30, 2014 and updated 2014 guidance. The press release is being furnished with this Current Report on Form 8-K as Exhibit 99.1 and is hereby incorporated by reference.

The information provided in this Item 2.02 (including Exhibit 99.1) shall not be deemed to be “filed” for purposes of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), nor shall it be incorporated by reference in any filing made by the Partnership pursuant to the Securities Act of 1933, as amended (the “Securities Act”), other than to the extent that such filing incorporates by reference any or all of such information by express reference thereto.

On July 24, 2014, the Partnership and Breitburn Energy Partners LP, a Delaware limited partnership (“BreitBurn”), issued a joint press release announcing that they have entered into an Agreement and Plan of Merger (the “Merger Agreement”) by and among the Partnership, QRE GP, LLC, a Delaware limited liability company and the general partner of the Partnership, Breitburn, Breitburn GP, LLC, a Delaware limited liability company and the general partner of BreitBurn, and Boom Merger Sub, LLC, a Delaware limited liability company and newly formed, wholly owned subsidiary of Breitburn (“Merger Sub”). Upon the terms and conditions set forth in the Merger Agreement, Merger Sub will be merged with and into the Partnership (the “Merger”), with the Partnership continuing as the surviving entity and as a wholly owned subsidiary of Breitburn.

The press release is being furnished with this Current Report on Form 8-K as Exhibit 99.2 and is hereby incorporated by reference.

Additional Information about the Proposed Transactions

In connection with the proposed transactions, Breitburn intends to file with the Securities and Exchange Commission (the “SEC”) a registration statement on Form S-4 that will include a prospectus of Breitburn and a proxy statement of QR Energy. Each of Breitburn and QR Energy also plan to file other relevant documents with the SEC regarding the proposed transactions. INVESTORS ARE URGED TO READ THE PROXY STATEMENT/PROSPECTUS AND OTHER RELEVANT DOCUMENTS FILED WITH THE SEC IF AND WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION. You may obtain a free copy of the proxy statement/prospectus (if and when it becomes available) and other relevant documents filed by Breitburn and QR Energy with the SEC at the SEC’s website at www.sec.gov. You may also obtain these documents by contacting Breitburn Investor Relations in writing at 515 S. Flower Street, Suite 4800, Los Angeles, CA, 90071, or via e-mail by using the “Contact Form” located at the Investor Relations tab at www.breitburn.com or by calling (213) 225-0390; or by contacting QR Energy Investor Relations in writing at 1401 McKinney Street, Suite 2400, Houston, TX 77010, or via e-mail at ir@qracq.com or by calling (713) 452-2990.

Participants in the Solicitation

Breitburn and QR Energy and their respective directors and executive officers and other members of management and employees may be deemed to be participants in the solicitation of proxies in respect of the proposed transactions. Information about Breitburn’s directors and executive officers is available in Breitburn’s proxy statement dated April 25, 2014, for its 2014 Annual Meeting of Unitholders. Information about QR Energy’s directors and executive officers is available in QR Energy’s proxy statement dated February 3, 2014, for its Special

Meeting of Unitholders held on March 10, 2014. Other information regarding the participants in the proxy solicitations and a description of their direct and indirect interests, by security holdings or otherwise, will be contained in the proxy statement/prospectus and other relevant materials to be filed with the SEC regarding the proposed transactions when they become available. Investors should read the proxy statement/prospectus carefully when it becomes available before making any voting or investment decisions. You may obtain free copies of these documents from Breitburn or QR Energy using the sources indicated above.

This document shall not constitute an offer to sell or the solicitation of an offer to buy any securities, nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. No offering of securities shall be made except by means of a prospectus meeting the requirements of Section 10 of the U.S. Securities Act of 1933, as amended.

Cautionary Statement Regarding Forward-Looking Information

This press release contains statements that Breitburn and QR Energy believe to be “forward-looking statements” within the meaning of Section 21E of the Securities Exchange Act of 1934. All statements other than historical facts, including, without limitation, statements regarding the expected benefits of the proposed transaction to Breitburn and QR Energy and their unitholders, the anticipated completion of the proposed transaction or the timing thereof, the expected future reserves, production, financial position, business strategy, revenues, earnings, costs, capital expenditures and debt levels of the combined company, and plans and objectives of management for future operations, are forward-looking statements. When used in this press release, words such as we “may,” “can,” “expect,” “intend,” “plan,” “estimate,” “anticipate,” “project,” “believe,” “will” or “should” or the negative thereof or variations thereon or similar terminology are generally intended to identify forward-looking statements. It is uncertain whether the events anticipated will transpire, or if they do occur what impact they will have on the results of operations and financial condition of Breitburn, QR Energy or of the combined company. Such forward-looking statements are subject to risks and uncertainties that could cause actual results to differ materially from those expressed in, or implied by, such statements.

These risks and uncertainties include, but are not limited to: the ability to obtain unitholder, court and regulatory approvals of the proposed transaction; the ability to complete the proposed transaction on anticipated terms and timetable; Breitburn’s and QR Energy’s ability to integrate successfully after the transaction and achieve anticipated benefits from the proposed transaction; the possibility that various closing conditions for the transaction may not be satisfied or waived; risks relating to any unforeseen liabilities of Breitburn or QR Energy; declines in oil, NGL or natural gas prices; the level of success in exploitation, development and production activities; adverse weather conditions that may negatively impact development or production activities; the timing of exploitation and development expenditures; the ability to obtain sufficient quantities of CO2 necessary to carry out EOR projects; inaccuracies of reserve estimates or assumptions underlying them; revisions to reserve estimates as a result of changes in commodity prices; impacts to financial statements as a result of impairment write-downs; risks related to level of indebtedness and periodic redeterminations of the borrowing base under Breitburn’s credit agreement; ability to generate sufficient cash flows from operations to meet the internally funded portion of any capital expenditures budget; ability to obtain external capital to finance exploitation and development operations and acquisitions; federal, state and local initiatives and efforts relating to the regulation of hydraulic fracturing; the ability to successfully complete potential asset dispositions and the risks related thereto; the impacts of hedging on results of operations; failure of properties to yield oil or gas in commercially viable quantities; uninsured or underinsured losses resulting from oil and gas operations; inability to access oil and gas markets due to market conditions or operational impediments; the impact and costs of compliance with laws and regulations governing oil and gas operations; ability to replace oil and natural gas reserves; any loss of senior management or technical personnel; competition in the oil and gas industry; risks arising out of hedging transactions; and other risks described under the caption “Risk Factors” in Breitburn’s and QR Energy’s Annual Reports on Form 10-K for the period ended December 31, 2013. Breitburn and QR Energy assume no obligation, and disclaim any duty, to update the forward-looking statements in this press release to reflect subsequent events or circumstances.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Dated: July 24, 2014

Exhibit Index