UPDATE 1-Encana, PetroChina take $2.2 bln stab at new joint venture

* Second attempt at cooperation between the two companies

* Petrochina gets 49.9 percent of Alberta gas joint venture

* Encana shares rise 3 percent, then edge back

(Adds details, background)

CALGARY, Alberta, Dec 13 (Reuters) - PetroChina will pay Encana Corp C$2.2 billion ($2.2 billion) for a 49.9 percent stake in a rich Alberta natural gas prospect owned by the Canadian company, a first test of Canada's new guidelines for major energy investments by foreign state-owned enterprises.

Under the deal, which follows a failed joint-venture attempt by the pair in 2011, a unit of PetroChina known as Phoenix Duvernay Gas will take the nearly-half interest in Encana's Duvernay play in west-central Alberta, estimated to contain 9 billion barrels of oil equivalent

It has already paid C$1.18 billion and the other C$1 billion is payable in the next four years by carrying Encana's share of development spending, Encana said.

With the agreement, Encana makes good on part of a high-profile effort to attract partners to help develop a host of prospects across North America that feature natural gas that is high in liquid hydrocarbon content. Such fuels are priced closer to oil than to dry gas, of which there is continent-wide glut that has driven down prices.

Encana shares were up 24 Canadian cents, or 1.2 percent, at C$20.68 on the Toronto Stock Exchange soon after the announcement.

"A transaction of this magnitude keeps us on track to create a more diversified commodity portfolio and maintain our balance sheet strength," Encana Chief Executive Randy Eresman said in a statement.

Encana announced the deal less than a week after Canada issued new guidelines for the takeover of Canadian resource assets by foreign state-owned companies. The guidelines were issued along with approvals for the takeovers of Nexen Inc by China's CNOOC Ltd and of Progress Energy Resources Corp by Malaysia's Petronas.

The new framework effectively bans enterprises controlled by foreign governments from taking control of more businesses in Canada's oil sands, but it is not yet known how it will affect other takeovers.

Encana does not cede control of its Duvernay assets in the joint venture.

Encana and PetroChina tried to set up a C$5.4 billion joint venture on British Columbia gas assets in 2011, but the deal fell through.

($1=$0.98 Canadian)

(Reporting by Jeffrey Jones; Editing by Janet Guttsman; and Peter Galloway)