MarkWest Announces Major Expansion of Processing and Fractionation Infrastructure in Butler County, PA

  MarkWest Announces Major Expansion of Processing and Fractionation
  Infrastructure in Butler County, PA

Business Wire

DENVER -- August 26, 2014

MarkWest Energy Partners, L.P. (NYSE: MWE) (“MarkWest” or “the Partnership”)
announced today a major expansion of midstream infrastructure at its Keystone
complex in Butler County, Pennsylvania, to support growing rich-gas production
from the Marcellus Shale and Upper Devonian formations. The expansion will be
supported by new agreements with Rex Energy Corporation (NASDAQ: REXX) (“Rex
Energy”) and EdgeMarc Energy (“EM Energy”). As part of these agreements,
MarkWest will construct Bluestone III and IV, both of which are 200 million
cubic feet per day (MMcf/d) plants that are expected to begin operations
during the fourth quarter of 2015 and the second quarter of 2016,
respectively. In addition, the Partnership will construct 40,000 barrels per
day (Bbl/d) of additional de-ethanization capacity and over 20,000 Bbl/d of
additional propane and heavier NGL fractionation capacity.

The Keystone complex currently consists of the Bluestone processing and
fractionation complex and the Sarsen processing facility which combined
currently provide 210 MMcf/d of processing capacity and 26,500 Bbl/d of
fractionation capacity. The Keystone complex is anchored by Rex Energy and in
May 2014, MarkWest began operations of the 120 MMcf/d Bluestone II plant and
10,000 Bbl/d each of ethane and propane plus fractionation capacity to
continue supporting Rex Energy’s growing rich-gas production. In addition to
the new Bluestone processing and fractionation plants, the Partnership
completed a 32 mile purity ethane pipeline connecting the Bluestone facility
to Sunoco’s Mariner West pipeline project.

In conjunction with additional processing and fractionation infrastructure,
MarkWest continues to develop its rich-gas gathering system throughout Butler
County and surrounding areas in order to support the growth of its producer
customers’ production.

“Our expansion of the Keystone complex is very strategic to producer activity
in Beaver, Butler and surrounding counties and we are very excited to continue
building our strong relationship with Rex and begin supporting EdgeMarc,”
stated Frank Semple, Chairman, President, and Chief Executive Officer of
MarkWest. “Since our acquisition of the Keystone assets over two years ago,
volumes continue to increase significantly and we are leading the development
of full-service midstream services in the highly prospective rich-gas areas of
the northwest Marcellus.”

MarkWest Energy Partners, L.P. is a master limited partnership engaged in the
gathering, processing and transportation of natural gas; the gathering,
transportation, fractionation, storage and marketing of natural gas liquids;
and the gathering and transportation of crude oil. MarkWest has a leading
presence in many unconventional gas plays including the Marcellus Shale, Utica
Shale, Huron/Berea Shale, Haynesville Shale, Woodford Shale and Granite Wash

This press release includes “forward-looking statements.” All statements other
than statements of historical facts included or incorporated herein may
constitute forward-looking statements. Actual results could vary significantly
from those expressed or implied in such statements and are subject to a number
of risks and uncertainties. Although MarkWest believes that the expectations
reflected in the forward-looking statements are reasonable, MarkWest can give
no assurance that such expectations will prove to be correct. The
forward-looking statements involve risks and uncertainties that affect
operations, financial performance, and other factors as discussed in filings
with the Securities and Exchange Commission (SEC). Among the factors that
could cause results to differ materially are those risks discussed in the
periodic reports filed with the SEC, including MarkWest’s Annual Report on
Form 10-K for the year ended December 31, 2013. You are urged to carefully
review and consider the cautionary statements and other disclosures made in
those filings, specifically those under the heading “Risk Factors.” MarkWest
does not undertake any duty to update any forward-looking statement except as
required by law.


MarkWest Energy Partners, L.P.
Frank Semple, 866-858-0482
Chairman, President & CEO
Nancy Buese, 866-858-0482
Executive VP & CFO
Josh Hallenbeck, 866-858-0482
VP of Finance & Treasurer
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