June 12 (Reuters) -

U.S. natural gas pipeline venture Mountain Valley Pipeline

said on Wednesday it was preparing the $7.85-billion pipe from

West Virginia to Virginia to operate, after receiving approval

from a U.S. energy regulator.

The Mountain Valley project, the biggest gas pipeline

currently under construction in the Northeast, has encountered

numerous regulatory and court fights that have stopped work

several times since construction began in 2018.

"Final preparations are underway to begin commercial

operations," a spokesperson at U.S. gas pipeline company

Equitrans Midstream ( ETRN ), the lead partner in the Mountain

Valley venture, told Reuters in an email.

Equitrans made its comments after the U.S. Federal

Energy Regulatory Commission approved Mountain Valley's request

to start the project.

Equitrans could not say when gas may start to flow

through the Mountain Valley pipe, which has a capacity of 2.0

billion cubic feet per day (bcfd).

One billion cubic feet is enough gas to supply about 5

million U.S. homes for a day.

Separately,

EQT

CEO Toby Rice told Natural Gas Intelligence at the

LDC Gas Forums Northeast conference in Boston that EQT started

to bring back online some of the 1 bcfd of production it started

curtailing in February when gas prices dropped.

EQT, the nation's biggest gas producer,

agreed in March to buy Equitrans in an all-stock deal, which

is expected to close in the fourth quarter. That would bring

back the pipeline business that EQT spun off in 2018.

Analysts expect some of EQT's increased output will flow

through Mountain Valley, but noted that downstream pipeline

constraints will likely prevent Mountain Valley from reaching

full capacity at least for a few more months.

"Output gains are likely to remain far short of

(Mountain Valley's 2.0-bcfd) nameplate capacity during the

summer months due to downstream pipeline constraints," analysts

at energy consulting firm EBW Analytics said in a note.

When Mountain Valley started construction, lead partner

Equitrans, with a roughly 49% interest, estimated the project

would cost about $3.5 billion and enter service by late 2018.

The 303-mile (488-km) project is owned by units of

Equitrans, NextEra Energy, Consolidated Edison ( ED ),

AltaGas ( ATGFF ) and RGC Resources ( RGCO ). Equitrans will

operate the pipeline.