ENMG Analysis
Two Texas gas pipeline expansions have entered service, adding firm transportation capacity for Houston-area delivery points and a planned power-plant conversion in South Texas. Williams now lists the Transco Gillis West and Wharton West projects as operational, but their in-service status does not establish how much natural gas is moving through them each day.
Together, the two projects represent 285,000 dekatherms per day of incremental firm transportation capacity. Gillis West accounts for 115,000 Dth/d, while Wharton West accounts for 170,000 Dth/d.
Williams disclosed the projects’ in-service status in its third-quarter earnings materials. The company’s presentation also reported that Gillis West, Wharton West, the Huntingdon Connector, and the Ryckman Creek Lateral added a combined 413 million cubic feet per day across Williams’ broader transmission portfolio.
That 413 MMcf/d total should not be treated as a Texas-only capacity addition. Huntingdon Connector and Ryckman Creek Lateral serve other markets. The Texas-specific figure supported by the two project disclosures is 285,000 Dth/d.
What Williams Has Confirmed
Williams’ November 3 presentation identifies both Gillis West and Wharton West as successfully placed in service. Its latest quarterly SEC filing provides a more precise timeline for Gillis West, stating that Transco placed it into service in late October 2026.
The filing does not provide an equivalent exact startup date for Wharton West. Williams’ presentation establishes that Wharton West was in service by the time the company released its third-quarter materials, but the public documents reviewed for this report do not specify the day commercial service began.
The in-service designations resolve an important project-development question. These are no longer merely proposed additions awaiting construction or authorization. However, the disclosures do not establish daily utilization, measured gas flow, or whether customers are currently using all their contracted capacity.
Firm transportation capacity generally means a customer has contracted for pipeline service that receives priority under the applicable tariff and agreement. That contractual commitment can support project development, but it does not require the customer to move the maximum quantity every day.
ENMG recently examined that distinction in its coverage of how contracted pipeline capacity is beginning to reflect growing Texas power and industrial demand. Reserved transportation rights, physical pipeline capability, and daily gas consumption are related, but they are not interchangeable measurements.
Gillis West Extends Louisiana Supply Into Texas
The Gillis West Expansion increases Transco’s ability to transport natural gas from Louisiana receipt points to delivery locations in Texas.
According to the Federal Energy Regulatory Commission notice, the project included three new delivery meter stations and modifications to Transco’s Station 35 in Harris County. It also included work at the existing Louisiana Southwest LW269 Valve Site in Beauregard and Allen parishes.
The project provides 115,000 Dth/d of incremental firm transportation capacity from Transco’s existing mainline in Beauregard Parish to three delivery points in Harris County.
The route gives customers another means of moving Louisiana gas into the Houston-area market. That could support utilities, industrial facilities, power generators, or other contracted customers, depending on the commercial arrangements behind the delivery points.
Williams and FERC have not publicly identified all the ultimate beneficiaries in the materials reviewed for this report. The project’s in-service status therefore supports a conclusion about available transportation capability—not a claim that particular Houston customers have already received a measured reliability or price benefit.
Wharton West Supports a Planned Power-Sector Fuel Change
Wharton West serves a more specifically identified customer and purpose.
FERC’s Wharton West project notice says the project provides 170,000 Dth/d of incremental firm transportation service to Luminant for the planned conversion of the Coleto Creek Power Plant from coal-fired to natural-gas-fired generation.
The project included piping and valving modifications at Compressor Station 30 in Wharton County, a new delivery interconnect in Goliad County, a new receipt interconnect in Live Oak County, and additional modifications at an existing valve site in Live Oak County.
Coleto Creek is a 650-megawatt coal-fired plant near Goliad. Vistra, Luminant’s parent company, has said it intends to repower the facility using natural gas after retiring its coal-fired operation.
Vistra’s latest available quarterly filing identifies the expected coal retirement as occurring by the end of 2026 and continues to describe the natural-gas repowering as an intended project. The filing does not establish that the conversion is complete or that the repowered plant has begun generating electricity.
That distinction is central to interpreting the Wharton West milestone. The pipeline can be available before the power plant it is intended to support completes every construction, commissioning, permitting, and operational step.
A pipeline entering service demonstrates that a fuel-delivery component is available. It does not, by itself, prove that a connected generator has completed conversion, passed operational testing, or begun commercial operation.
Capacity Is Not the Same as Daily Flow
Williams reports the projects’ capacity in dekatherms per day. A dekatherm is a measure of energy equal to 10 therms, or approximately one million British thermal units.
Cubic feet measure physical gas volume. Because the heat content of natural gas can vary, Dth and cubic feet are not universally interchangeable without a stated conversion assumption.
Williams says its presentation uses a convention of 1,000 cubic feet per dekatherm. Under that convention, the two Texas projects’ combined 285,000 Dth/d would correspond to approximately 285 MMcf/d of transportation capacity.
That is a standardized capacity comparison, not evidence that the pipelines transported 285 MMcf on a particular day. Actual flows depend on customer nominations, downstream demand, operating conditions, upstream supply, maintenance, pressure, and other pipeline-system requirements.
The difference matters when evaluating infrastructure announcements. A project can be fully in service while operating below its maximum capacity. Conversely, available firm capacity can still have commercial and reliability value even when customers do not use all of it every day.
Why Deliverability Matters
Texas and neighboring producing regions have substantial natural-gas supplies, but production alone does not ensure that gas can reach a particular customer when it is needed.
Pipelines, storage facilities, compressors, interconnections, and firm transportation agreements determine where gas can move and how quickly it can be delivered. ENMG’s analysis of Texas gas storage and Gulf Coast deliverability explains why having sufficient gas over a month is different from having it available at the correct pipeline connection on a specific day.
Gillis West adds another route from Louisiana supply into Harris County. Wharton West creates transportation capability tied to a planned fuel conversion at a specific South Texas power plant. Those are different commercial roles, even though both projects expand the same Transco system.
For power generation, firm pipeline service can reduce exposure to interruptions associated with lower-priority transportation. It does not eliminate every fuel risk. Generator reliability also depends on upstream supply, storage access, compressor performance, equipment condition, weather preparation, and the power plant’s ability to operate.
Electric reliability adds another layer. Even after a gas-fired facility has fuel, its electricity must move through the transmission system to reach customers. ENMG has separately examined how Texas transmission constraints can limit power delivery even as generation and fuel infrastructure expand.
What These Projects Do Not Yet Prove
Neither project’s startup guarantees lower natural-gas or electricity prices.
Pipeline additions can improve transportation options, but customer costs depend on tariffs, contracted quantities, fuel prices, power-market conditions, infrastructure cost recovery, and actual use. Williams has not published a quantified household-bill effect for either project.
The disclosures also do not establish:
- Daily scheduled or measured gas deliveries
- Initial utilization rates
- Whether every customer is taking its full contract quantity
- A completed conversion at Coleto Creek
- Commercial operation of a repowered gas facility
- A measured improvement in electric reliability
- A specific reduction in customer energy costs
These are not reasons to dismiss the projects. They are the measurements needed to evaluate what the infrastructure accomplishes after startup.
What to Watch Next
The next reporting step is to move from project status to operating evidence.
For Gillis West, that means identifying the customers associated with the Harris County delivery points and determining whether initial nominations and measured flows are approaching the project’s available capacity.
For Wharton West, the key questions concern Coleto Creek. Vistra should confirm the coal unit’s retirement schedule, construction and commissioning milestones for the gas repowering, expected commercial-operation date, and initial fuel requirements.
Williams should also clarify Wharton West’s exact startup date and disclose initial utilization where commercially permissible.
The update is meaningful without stretching it. Two Texas gas pipeline expansions that ENMG had been tracking are now listed in service. Gillis West adds a route into the Houston-area market, while Wharton West supplies transportation capability for a planned South Texas power-sector conversion.
Whether those additions produce sustained deliveries, a successful plant repowering, stronger reliability, or measurable customer benefits will depend on operating data that comes next.
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