SemGroup Corporation Closes Acquisition of Mississippi Lime Midstream Assets from Chesapeake Energy Corporation

SemGroup Corporation Closes Acquisition of Mississippi Lime Midstream Assets
from Chesapeake Energy Corporation

TULSA, Okla., Aug. 1, 2013 (GLOBE NEWSWIRE) -- SemGroup^® Corporation
(NYSE:SEMG) today announced it completed its previously disclosed acquisition
of the gas gathering and processing assets owned by Chesapeake Energy
Corporation (NYSE:CHK), located in the Mississippi Lime play for $300 million
in cash. Approximately $125 million of additional capital expenditures will be
required for the completion of the Rose Valley plants I and II, as well as
additional capital related to future well connects.

Acquisition Highlights

  *200 miles of gathering pipeline;
  *Rose Valley I plant: 200 mmcfd cryogenic processing plant, expected to be
    operational first quarter 2014;
  *Rose Valley II plant: 200 mmcfd cryogenic processing plant, expected to be
    operational first quarter 2016;
  *Approximately 540,000 net acre dedication in the core of the Mississippi
    Lime play; and
  *20-year, 100% fee-based, gas gathering and processing agreement.

"We are pleased to add all of these key assets to SemGroup's continued story
of growth," said Norm Szydlowski, president and chief executive officer of
SemGroup. "This purchase positions us to expand our presence in a highly
attractive area and provides future drop down inventory for Rose Rock

LCT Capital, LLC and Citi acted as financial advisors to SemGroup.

The company will be hosting its second quarter earnings call August 9, 2013.
Interested parties are invited to listen to the call with management regarding
the acquisition and second quarter 2013 results at 11:00 AM Eastern by dialing
877.359.3652 (International 720.545.0014), passcode 10053658 or by logging on
to the webcast at

About SemGroup

Based in Tulsa, OK, 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

SemGroup®, is a registered trademark of SemGroup Corporation

About Rose Rock Midstream

Rose Rock Midstream, L.P. (NYSE:RRMS) is a growth-oriented Delaware limited
partnership formed by SemGroup® Corporation (NYSE:SEMG) 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 states with the majority of its assets strategically located
in or connected to the Cushing, Oklahoma crude oil marketing hub.

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 prospects of our industry, our anticipated
financial performance, management's plans and objectives for future
operations, business prospects, market conditions and other matters, 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, our ability to comply with the covenants contained in and maintain certain
financial ratios required by our credit facilities; any sustained reduction in
demand for the petroleum products we gather, transport, process and store; our
ability to obtain new sources of supply of petroleum products; our failure to
comply with new or existing environmental laws or regulations or cross border
laws or regulations; the possibility that the construction or acquisition of
new assets may not result in the corresponding anticipated revenue increases;
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:
         Mary Catherine Ward
         Kiley Roberson

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