Williams Partners Provides Update on Investment in Utica Shale Joint Venture; Caiman Energy II JV to Partner with Dominion

  Williams Partners Provides Update on Investment in Utica Shale Joint
  Venture; Caiman Energy II JV to Partner with Dominion

  *Blue Racer Midstream to Be Developed Around Dominion’s (NYSE:D) Assets,
    Provide Utica Shale Producers with Gathering, Processing, Fractionation,
    NGL Transportation and Marketing
  *Williams Partners Plans to Invest Approximately $380 Million Through 2014
    for its Proportional Interest in Blue Racer Midstream’s Development Plan
    in Utica Shale
  *Planned Capital Amount Included in Previous Guidance

Business Wire

TULSA, Okla. -- December 20, 2012

Williams Partners L.P. (NYSE:WPZ) today announced an update on its 47.5
percent interest in Caiman Energy II, which was established by Caiman and its
investors to develop midstream infrastructure serving oil and gas producers in
the Utica Shale. In addition to Williams Partners, investors in Caiman Energy
II include EnCap Flatrock Midstream of San Antonio, Highstar Capital of New
York and management.

Williams Partners plans to contribute approximately $380 million through 2014
to help fund Caiman Energy II’s new Blue Racer Midstream venture. EnCap
Flatrock Midstream is expected to contribute up to $285 million with Highstar
contributing up to $95 million. Caiman and Dominion formed Blue Racer, which
will leverage Dominion’s existing business in the Utica with significant
additional new capacity designed to meet producer needs as the Utica Shale
acreage is developed. Midstream services offered will include gathering,
processing, fractionation, and natural gas liquids transportation and
marketing.

“Through our interest in Caiman Energy II, Blue Racer Midstream gives us
additional exposure to the Utica Shale, which is one of the fastest growing
resource plays in North America,” said Alan Armstrong, chief executive officer
of Williams Partners’ general partner. “We believe this venture has all the
elements to be highly successful in delivering timely, safe and reliable
midstream services to producers in this fast-growing area. We are excited to
be partnering with Dominion, a well established operator with well positioned
assets in this region, and Caiman who continues to demonstrate strong
development capabilities.”

The approximate $380 million that Williams Partners expects to invest in
Caiman Energy II was included in previous 2012-14 capital expenditure
guidance. The partnership expects growing cash distributions from its
investment in Caiman Energy II beginning with approximately $20 million in
2014. Williams expects to account for its Caiman Energy II investment using
the equity method.

Williams Partners’ current ownership interest in Caiman Energy II is 47.5
percent with EnCap Flatrock Midstream owning 35.6 percent, Highstar Capital
owning 11.5 percent and management owning 4 percent.

About Williams Partners L.P. (NYSE: WPZ)

Williams Partners L.P. is a leading diversified master limited partnership
focused on natural gas transportation; gathering, treating, and processing;
storage; natural gas liquid (NGL) fractionation; and oil transportation. The
partnership owns interests in three major interstate natural gas pipelines
that, combined, deliver 14 percent of the natural gas consumed in the United
States. The partnership’s gathering and processing assets include large-scale
operations in the U.S. Rocky Mountains and both onshore and offshore along the
Gulf of Mexico. Williams (NYSE: WMB) owns approximately 70 percent of Williams
Partners, including the general-partner interest. More information is
available at www.williamslp.com, where the partnership routinely posts
important information.

Portions of this document may constitute “forward-looking statements” as
defined by federal law. Although the partnership believes any such statements
are based on reasonable assumptions, there is no assurance that actual
outcomes will not be materially different. Any such statements are made in
reliance on the “safe harbor” protections provided under the Private
Securities Reform Act of 1995. Additional information about issues that could
lead to material changes in performance is contained in the partnership’s
annual reports filed with the Securities and Exchange Commission.

Contact:

Williams Partners L.P.
Media Contact:
Jeff Pounds, 918-573-3332
or
Investor Contacts:
John Porter, 918-573-0797
or
Sharna Reingold, 918-573-2078