Williams on Thursday restricted some natural gas pipeline services on its mainstay Transcontinental Gas Pipe Line LLC (aka Transco) because of capacity constraints in the Pennsylvania portion of the Marcellus Shale.

In a website posting, Transco said it was monitoring and restricting interruptible transportation, including secondary firm transportation, for services north of a constraint near Station 195 in southeastern Pennsylvania for deliveries south.

A lack of infrastructure has hindered the gasline, which has the capacity to carry 9.9 Bcf/d to markets across the Northeast and Southeast. However, Transco said it can’t accommodate gas transportation past the 195 station because receipts can’t exceed deliveries north of it.

More reductions in transportation could be required on the Leidy line at Station 515 in Luzerne County, PA, to alleviate conditions, Transco said. “Additional reductions of interruptible and secondary transportation may be required on the Leidy line at Station 515 to alleviate the condition.”

Last month the system ramped up the Palmerton Loop in Monroe County, PA, the first loop on its Northeast Supply Link extension to move gas out of the Marcellus (see NGI, July 15). Williams now is installing a 16,000 hp natural gas turbine-driven compressor unit at the Leidy station.

Williams last week issued its 2Q2013 results, reporting steadily increasing gas volumes in the Northeast, which lifted Williams Partners LP to a new monthly average in June of 1.83 Bcf/d, with volumes between April and June jumping 76% year/year. However, the pipeline unit and majority owner Williams were slapped by still-slumping natural gas liquids (NGL) margins, down sharply from a year ago.

Net income was higher year/year at $142 million (21 cents/share) from $132 million (also 21 cents). However, adjusted income came in at $129 million (19 cents), down slightly from a year ago, mostly because of NGL margins, down 44% year/year. The losses were offset by higher fee revenues and olefin margins from majority-owned Williams Partners LP.

NGL margins dropped to $105 million in 2Q2013 from $189 million in 2Q2012, and they were down 13% from 1Q2013’s $121 million. Ethane equity sales plunged by 78% between April through June year/year to 37 million gallons from 166 million gallons. Per-unit ethane NGL margins/gallon fell 91% to 2 cents, versus 22 cents in both 2Q2012 and 1Q2013. Ex-ethane margins also declined by 29%.

Quarterly net income was higher from a year earlier “primarily due to an increase in fee revenues at Williams Partners,” but it was “substantially offset by lower commodity margins,” said CEO Alan Armstrong.

Williams’ business units include the gas pipeline plum, as well as an NGL/petrochemical unit and a 50% stake in Access Midstream Partners LP, which reported its earnings also last week. Together the three units scored $456 million in profits in the latest period, versus $409 million a year ago. Williams Partners carried the earnings at $403 million from year-ago profits of $391 million.

Williams Pipeline’s NGL margins suffered not only on prices, but because of the June incident at the Geismar Olefins plant in Louisiana, which claimed two lives (see NGI, July 1). Between January and March, Williams’ NGL margins also had been depressed, but higher olefin margins, particularly higher ethylene margins at Geismar, helped to mitigate the impact (see NGI, May 9).

Armstrong said the Geismar unit expects to hit an April 2014 target in-service date and bring online at the same time an expansion to increase ethylene production capacity by 50%. Geismar’s interruption will be mitigated by $500 million of combined business interruption and property damage insurance. The current estimate of uninsured business interruption is $95 million and the company now estimates it would receive $384 million for the losses.

Meanwhile, in the Northeast, expansions to the Susquehanna Supply Hub gathering system in Pennsylvania are keeping “pace” with long-time producer partner Cabot Oil & Gas Corp., which is adding a sixth rig to the Marcellus later this month.

Williams also is pursuing an OK from the Federal Energy Regulatory Commission to build the Constitution Pipeline, a 120-mile gas pipeline system to connect by 2015 Marcellus gas to northeastern markets (see NGI, June 17). Also sanctioned by the Williams board is Bluegrass Pipeline to carry liquids from the Northeast to petrochemical markets on the East and Gulf coasts (seeNGI, June 3; March 11).

The number of Marcellus gas wells waiting on infrastructure provided by Access has fallen by more than half since the end of 2012, Access CEO J. Mike Stice said last week. At the end of 2012, the company had 250 Marcellus wells waiting on pipeline. By the end of June, the number had fallen to “less than 115,” Stice said. That additional infrastructure helped to break throughput records across the play. From April through June, Marcellus output averaged 930 MMcf/d, an increase of nearly 50% from the same period a year ago. Total gas throughput averaged 333.5 Bcf, about 3.67 Bcf/d, nearly 28% more than year-ago output of 2.87 Bcf/d.