Atlas Pipeline Partners, L.P. to Acquire 75% Interest in the NOARK Pipeline System for $163 Million.

PHILADELPHIA -- Atlas Pipeline Partners, L.P. (NYSE:APL) (the "Partnership") announces that it has entered into an agreement with a subsidiary of OGE Energy Corp. (NYSE:OGE) to acquire a subsidiary which owns a 75% operating interest in NOARK Pipeline System, L.P. ("NOARK"). NOARK's assets, which will be included within the Partnership's Mid-Continent operations, include a FERC regulated interstate pipeline and an unregulated natural gas gathering system. Total consideration will be $163 million, subject to working capital adjustments. Consummation of the acquisition, expected to occur in the fourth quarter of 2005, is subject to approval under the Hart-Scott Rodino Act and other customary closing conditions.

The Partnership expects this acquisition to be immediately accretive to distributable cash flow upon closing of the transaction and to provide additional significant fixed fee revenues, with substantially all of NOARK's gross profit generated from fixed fee arrangements. The Partnership expects the acquisition to generate $15 million to $18 million of cash flow in 2006, and to increase distributions to limited partners by $0.10 to $0.20 in 2006.

NOARK, through its 100% ownership of Ozark Gas Transmission, L.L.C. ("OGT"), operates 565 miles of FERC regulated interstate pipeline, extending from eastern Oklahoma through central and northeastern Arkansas and into Missouri. OGT has throughput capacity of approximately 322,000 dth/d. OGT currently transports approximately 202,200 dth/d. In addition, NOARK, through its 100% ownership of Ozark Gas Gathering, L.L.C. ("OGG"), operates 365 miles of unregulated gathering pipeline in Oklahoma and Arkansas. OGG provides access to natural gas basins through approximately 400 receipt points that are then transported through OGT. OGG currently gathers approximately 36,400 mcf/d.

Edward E. Cohen, Chairman and C.E.O. of the general partner of the Partnership, stated "We are very excited by the opportunity to acquire this interest in NOARK and expand APL into the long-haul pipeline business through its ownership in OGT, and through OGG, expand our gathering business. Through the addition of these assets, we continue to execute our strategy to expand our activity in the mid-continent area. In addition, the stable fixed fee revenue from both OGT and OGG will continue to diversify our contract mix."

Robert R. Firth, President of Atlas Pipeline Mid-Continent, stated "We believe this acquisition offers a unique opportunity to expand the mid-continent business and increase our cash flows. In addition, we anticipate future organic growth on this system as a result of improving basis trends as well as increasing drilling activity in the Fayetteville shale."

The Partnership will host a conference call to discuss the acquisition on Thursday, September 22, 2005 at 10:00 a.m. EDT. All interested parties can access the live webcast of the call from the home page of the Atlas Pipeline Partners, L.P. website at www.atlaspipelinepartners.com. For those who cannot listen to the live broadcast, the replay of the webcast will be available following the live call on the website and telephonically starting at noon eastern time on September 22, 2005 until midnight on October 22, 2005 by dialing 888-286-8010 and using the passcode 50103047.

Banc of America Securities, LLC acted as financial advisor to APL and provided a fairness opinion to the Managing Board of the general partner of the Partnership. Vinson & Elkins LLP and Ledgewood acted as legal counsel to APL.

The Partnership has received a commitment to finance the acquisition from Wachovia Bank, National Association and Bank of America, N.A., which will expand the Partnership's current $225 million 5-year revolving loan.

Atlas Pipeline Partners, L.P. is active in the gas gathering and processing segment of the mid-stream natural gas industry. In the Mid-Continent region of Oklahoma and northern Texas, APL owns and operates approximately 2,200 miles of gas gathering pipeline. APL transports approximately 320 million cubic feet of gas per day from more than 880 receipt points or wells to its gas processing and treating facilities in Velma, Elk City and Prentiss, Oklahoma where natural gas liquids (NGL) and impurities are removed. APL then sells the resulting residue gas and NGL and remits a portion of those proceeds to the producer. In Appalachia, it owns and operates more than 1,440 miles of natural gas gathering pipelines in western Pennsylvania, western New York and eastern Ohio to which more than 4,850 wells are currently connected. APL gathers approximately 58 million cubic feet ("mmcf") of gas per day from these wells. In the Mid-Continent and in Appalachia the fees paid to APL are based on a percentage of the gross selling price of the gas or NGL, fixed fee per mcf transported or on percent of index. For more information, visit our website at www.atlaspipelinepartners.com or contact [e-mail].

Statements made in this release include forward-looking statements, which involve substantial risks and uncertainties. The Partnership's actual results, performance or achievements could differ materially from those expressed or implied in this release. NOARK and its subsidiaries are subject to the risks typically associated with natural gas pipelines, including risks associated with replacing natural gas production declines of wells currently connected to its pipelines with new wells, its ability to expand its pipelines, adverse climatic conditions, adverse changes in the price of natural gas and increased costs of supplies and services. The Partnership discusses these risks in its Annual Report on Form 10-K. In addition, NOARK and its subsidiaries are subject to additional risks including the possibility that production from wells connected to its pipelines will be less than projected, that natural gas transported through NOARK's pipelines from outside sources will be less than projected, that regulatory challenges to its pipeline transportation rates could be brought which could lead to reductions in rates or requirements to make reparation or refund payments, that new regulatory requirements relating to pipeline integrity or safety would require substantial capital or other expenditures, or that other regulatory policy changes could occur that would lead to increased costs or reduced transportation rates. Moreover, the Partnership may encounter difficulties in integrating NOARK into its operations since, if the acquisition is completed, it would be the Partnership's third major acquisition in less than two years and since the Partnership has no prior experience in operating a pipeline regulated by FERC. As a result, the Partnership may not realize anticipated operating advantages or cost savings, may have difficulty in integrating NOARK's operating and reporting systems with the Partnership's existing systems and may not be able to maintain operating efficiencies. The occurrence of any of the foregoing risks could reduce the Partnership's revenues, cash flows and ability to make distributions.