SemGroup, L.P. Announces Planned Public Offering and Filing of Registration Statement by SemGroup Energy Partners, L.P.

SemGroup, L.P. ("SemGroup") announced today it has filed a
registration statement on Form S-1 with the Securities and Exchange
Commission. The filing is related to a proposed public offering of
12,500,000 common units, representing limited partner interests in
SemGroup Energy Partners, L.P. ("SemGroup Energy Partners") to be sold
by a wholly owned subsidiary of SemGroup. The filing includes an
option for the underwriters to purchase up to an additional 1,875,000
common units to be sold by SemGroup Energy Partners. An application
has been made to have the units quoted on the NASDAQ Global Market
under the symbol "SGLP."

Proceeds from this offering, together with proceeds received from
SemGroup Energy Partners pursuant to borrowings under a credit
facility to be established by SemGroup Energy Partners, will be used
by SemGroup to reduce amounts outstanding under its senior secured
credit facilities. SemGroup Energy Partners will use any proceeds it
receives from the underwriters' over-allotment option to reduce
outstanding borrowings under its proposed credit facility.

As currently filed, the common units offered to the public will
represent approximately 59.3 percent of the outstanding equity of
SemGroup Energy Partners, or approximately 62.5 percent if the
underwriters exercise in full their over-allotment option. SemGroup
will remain a privately held company and will indirectly own the
remaining equity interests in SemGroup Energy Partners.

Citigroup Global Markets Inc. will act as the bookrunning manager
of the offering. This offering of common units will be made only by
means of a prospectus. A written prospectus meeting the requirements
of Section 10 of the Securities Act of 1933, when available, may be
obtained from the offices of Citigroup Global Markets Inc., Brooklyn
Army Terminal, Attn: Prospectus Delivery Department, 140 58th Street,
Brooklyn, New York 11220, phone: 718-765- 6732.

A registration statement relating to these securities has been
filed with the Securities and Exchange Commission but has not yet
become effective. These securities may not be sold nor may offers to
buy be accepted prior to the time the registration statement becomes
effective. This news release does not constitute an offer to sell and
is not a solicitation of an offer to buy. There will not be any sale
of these securities in any state in which such offer, sale or
solicitation is unlawful prior to registration or qualification under
the securities law in any such state.

About SemGroup Energy Partners

SemGroup Energy Partners was recently formed by SemGroup to own,
operate and develop a diversified portfolio of complementary midstream
energy assets. SemGroup Energy Partners will provide crude oil
gathering, transportation, terminalling and storage services primarily
in its core operating areas in Oklahoma, Kansas and Texas. A
subsidiary of SemGroup is the general partner of SemGroup Energy
Partners. As of the closing of this offering, SemGroup Energy Partners
will own and operate terminalling and storage facilities with
approximately 6.7 million barrels of storage capacity, including
approximately 4.8 million barrels of storage capacity located at the
Cushing Interchange, two pipeline systems consisting of approximately
1,120 miles of pipeline, and crude oil transports used to gather oil
at remote wellhead locations generally not covered by pipeline and
gathering systems.

SemGroup Energy Partners' principal executive offices are located
at Two Warren Place, 6120 South Yale Avenue, Suite 700, Tulsa,
Oklahoma 74136 and its telephone number is (918) 524-8100.

About SemGroup

SemGroup, L.P. is a privately held midstream company providing the
energy industry means to move products from the wellhead to the
wholesale marketplace. With operations in the United States, Canada,
Mexico, Wales (United Kingdom), Switzerland and Vietnam, SemGroup's
business segments focus on activities related to crude oil, refined
petroleum products, natural gas, natural gas liquids and asphalt.
Based in Tulsa, Oklahoma, SemGroup has been ranked in the top 10 of
Forbes magazine's list of America's Largest Private Companies for the
past two years.

Forward-Looking Statements

Statements about the proposed offering are forward-looking
statements within the meaning of the Private Securities Litigation
Reform Act of 1995. These forward-looking statements rely on a number
of assumptions concerning future events and are subject to a number of
uncertainties and factors, many of which are outside SemGroup's
control, and a variety of risks that could cause results to differ
materially from those expected by management of SemGroup or SemGroup
Energy Partners.