Kevin L. Burdick
Executive Vice President and Chief Commercial Officer at ONEOK
Thank you, Walt. During the second quarter, we saw NGL volume growth across all our operating regions compared with the first quarter 2022. NGL volume expectations remain strong through the remainder of the year, providing confidence in achieving the midpoint of our raw feed throughput guidance for 2022. Natural gas processed volumes and well completions during the quarter were significantly impacted by the April weather events and we now expect process volumes to be toward the lower end of our 2022 volume guidance range.
Let's take a closer look at our natural gas liquids segment. Total NGL raw feed throughput volumes increased 5% year-over-year and 4% compared with the first quarter 2022. Rocky Mountain region NGL volumes increased 10% year-over-year and 5% compared with the first quarter 2022. Activity in the region has rebounded following the April storms as July volumes averaged more than 360,000 barrels per day, 9% higher than the second quarter average.
Mid-Continent NGL volumes increased 4% compared with the first quarter 2022 driven by increased C3+ volumes as producers continued to add rigs in the basin with a large majority of the region's NGLs dedicated to ONEOK system. In the Permian Basin, NGL volumes increased 10% year-over-year and 4% compared with the first quarter of 2022. We recently completed a 25,000 barrel per day expansion on a portion of our West Texas NGL pipeline in the basin to support continued expected volume growth.
We saw increased ethane volumes on our system in the second quarter of 2022 and expect continued opportunities for ethane to be recovered through the remainder of the year. We anticipate high levels of recovery in the Permian Basin, periodic recovery in the Mid-Continent and continued opportunities to incentivize ethane recovery in the Rocky Mountain region as in-basin natural gas prices fluctuate. Our fractionation capacity is fully utilized following the incident at our Medford facility.
And as Pierce mentioned earlier, we have worked with industry peers to secure additional fractionation and storage capacity. Medford's capacity was approximately 210,000 barrels per day of our total system-wide nameplate capacity of more than 980,000 barrels per day. Construction continues on our 125,000 barrel per day MB-5 fractionator in Mont Belvieu, which we now expect to be complete early in the second quarter of 2023. Moving on to the natural gas gathering and processing segment.
In the Rocky Mountain region, second quarter processed volumes averaged more than 1.2 billion cubic feet per day, a slight decrease compared with the first quarter 2022 due to the April weather. We've seen recent volumes return to pre-storm levels, and in July, volumes reached approximately 1.4 billion cubic feet per day. Through the first six months of the year, we've connected 157 wells in the region and we continue to expect approximately 375 to 425 well connections in the region this year.
There are currently approximately 45 rigs and 18 completion crews operating in the basin, with 21 rigs and approximately half the completion crews on our dedicated acreage. Basin-wide, rigs have more than doubled in the last 12 months from only 20 rigs total in July 2021. As we've said before, approximately 15 rigs on our acreage can maintain natural gas production at current levels. But with more than 20 currently on our acreage, we expect to see higher well connections in 2023 compared with 2022 if these activity levels remain.
The basin-wide DUC inventory remains at approximately 500, with half of those on our dedicated acreage. This compares with approximately 650 DUCs in a basin a year ago. Recent producer M&A in the Williston Basin continues to show the value and long-term viability of the play. We see these recent announcements as positive for ONEOK as we expect increased activity from the acquirers to drive NGL and natural gas volumes to our system.
In the Mid-Continent region, we continue to see increased activity with four rigs now operating on our acreage and 46 rigs basin-wide. We expect steady to increasing activity through the remainder of the year with the majority of rigs basin-wide driving additional NGLs to our system. In the Natural Gas Pipelines segment, strong second quarter results benefited from the continued increasing demand for natural gas storage and transportation services.
Last quarter, we discussed a recently completed 1.1 billion cubic feet expansion of our Texas storage facility, which is now fully subscribed through 2032. Additionally, we are expanding our storage capabilities in Oklahoma, enabling an additional four billion cubic feet of storage capacity to be contracted. This project is expected to be complete in early 2023, and is nearly 90% subscribed through 2029.
We also recently completed two open seasons for additional pipeline capacity to address increased demand: one on our West Texas pipeline system in the Permian Basin and one on our Viking pipeline in the upper Midwest. Both open seasons were successful, and we plan to move forward with low capital expansions on both systems. The value of our natural gas pipelines and storage assets continue to be highlighted in the outperformance we've seen from this segment so far this year.
Pierce, that concludes my remarks.