SemGroup Corporation and Gavilon to Increase Ownership of Glass Mountain Pipeline

SemGroup Corporation and Gavilon to Increase Ownership of Glass Mountain
Pipeline

TULSA, Okla., Oct. 10, 2012 (GLOBE NEWSWIRE) -- SemGroup® Corporation
(NYSE:SEMG), and Gavilon, LLC, today announced that each has completed the
acquisition of a 25 percent share of Glass Mountain Pipeline LLC previously
owned by an affiliate of Chesapeake Energy Corporation (NYSE:CHK). Following
this purchase, SemGroup Corporation now owns 50 percent of Glass Mountain
Pipeline; the remaining 50 percent of the pipeline is now owned by Gavilon.
Chesapeake will maintain its long-term transportation agreement with Glass
Mountain Pipeline, providing the economic incentive for its construction.

SemGroup Corporation logo

Chesapeake Energy + Gavilon Logos

The Glass Mountain Pipeline will have an initial capacity of approximately
140,000 barrels per day and 440,000 barrels of intermediate storage. The
pipeline will consist of two laterals. One lateral will originate near the
town of Alva in Woods County, Oklahoma. The second lateral will originate near
the town of Arnett in Ellis County, Oklahoma. The pipeline will increase in
diameter where the laterals intersect near Cleo Springs in Major County,
Oklahoma and continue east to Cushing, Oklahoma. The pipeline will terminate
at Gavilon's Cushing facility, where the joint venture will own one million
barrels of crude oil storage. Following pipeline construction, Rose Rock
Midstream, LP (NYSE:RRMS), SemGroup's master limited partnership, will serve
as the pipeline operator.

About SemGroup

Based in Tulsa, Oklahoma, SemGroup® Corporation (NYSE:SEMG) is a publicly
traded midstream service company providing the energy industry the means to
move products from the wellhead to the wholesale marketplace. SemGroup
provides diversified services for end users and consumers of crude oil,
natural gas, natural gas liquids, refined products and asphalt. Services
include purchasing, selling, processing, transporting, terminalling and
storing energy.

SemGroup®, is a registered trademark of SemGroup Corporation.

The SemGroup Corporation logo is available at
http://www.globenewswire.com/newsroom/prs/?pkgid=14815

About Rose Rock Midstream

Rose Rock Midstream, L.P. (NYSE:RRMS) is a growth-oriented Delaware limited
partnership recently formed by SemGroup® Corporation to own, operate, develop
and acquire a diversified portfolio of midstream energy assets. Rose Rock
Midstream provides crude oil gathering, transportation, storage and marketing
services. Headquartered in Tulsa, OK, Rose Rock Midstream has operations in
six different states with the majority of its assets strategically located in
or connected to the Cushing, Oklahoma crude oil marketing hub.

About Chesapeake Energy Corporation

Chesapeake Energy Corporation (NYSE:CHK) is the second-largest producer of
natural gas, a Top 15 producer of oil and natural gas liquids and the most
active driller of new wells in the U.S. Headquartered in Oklahoma City, the
company's operations are focused on discovering and developing unconventional
natural gas and oil fields onshore in the U.S. Chesapeake owns leading
positions in the Eagle Ford, Utica, Granite Wash, Cleveland, Tonkawa,
Mississippi Lime and Niobrara unconventional liquids plays and in the
Marcellus, Haynesville/Bossier and Barnett unconventional natural gas shale
plays. The company also owns substantial marketing and oilfield services
businesses through its subsidiaries Chesapeake Energy Marketing, Inc. and
Chesapeake Oilfield Services, L.L.C. Further information is available at
www.chk.com where Chesapeake routinely posts announcements, updates, events,
investor information, presentations and news releases.

The Chesapeake Energy Corporation logo is available at
http://www.globenewswire.com/newsroom/prs/?pkgid=15147

About Gavilon, LLC

Gavilon, LLC is a subsidiary of The Gavilon Group, LLC. The Gavilon Group is a
leading commodity management firm, connecting producers and consumers of feed,
food and fuel through its global supply chain network. Gavilon leverages its
strategic partnerships and more than 300 facilities and regional offices
worldwide to link agricultural and energy supply with demand. The company
provides origination, storage and handling, transportation and logistics,
marketing and distribution, and risk management services to tens of thousands
of customers each year. Headquartered in Omaha, Nebraska, Gavilon employs
2,000 people around the world and is ranked America's nineteenth largest
private company by Forbes. For more information, please visit www.gavilon.com.

The Gavilon, LLC logo is available at
http://www.globenewswire.com/newsroom/prs/?pkgid=15148

Forward-Looking Statements

Certain matters contained in this Press Release include "forward-looking
statements" within the meaning of Section 27A of the Securities Act of 1933,
as amended, and Section 21E of the Securities Exchange Act of 1934, as
amended. We make these forward-looking statements in reliance on the safe
harbor protections provided under the Private Securities Litigation Reform Act
of 1995.

All statements, other than statements of historical fact, included in this
Press Release including the initial capacity and anticipated completion date
of the pipeline, may constitute forward-looking statements. Although we
believe that the expectations reflected in these forward-looking statements
are reasonable, we cannot assure you that these expectations will prove to be
correct. These forward-looking statements are subject to certain known and
unknown risks and uncertainties, as well as assumptions that could cause
actual results to differ materially from those reflected in these
forward-looking statements. Factors that might cause actual results to differ
include, but are not limited to, the possibility that we may encounter
construction delays beyond our control, as well as other risk factors
discussed from time to time in each of our documents and reports filed with
the SEC.

Readers are cautioned not to place undue reliance on any forward-looking
statements contained in this Press Release, which reflect management's
opinions only as of the date hereof. Except as required by law, we undertake
no obligation to revise or publicly release the results of any revision to any
forward-looking statements.

CONTACT: Investor Relations:
         Alisa Perkins, 918-524-8081
         investor.relations@semgroupcorp.com
        
         Media:
         Liz Barclay, 918-524-8158
         lbarclay@semgroupcorp.com

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