Of those, only approximately 113,000 of these wells were located offshore or in coastal waters. And yet, according to the EIA, production from federal offshore wells have averaged approximately 21% of total U.S. production over the last two decades. The sheer size and scale of the resource in the Gulf of Mexico being produced from such a relatively small percentage of the existing and valid leases, its proximity to the Gulf Coast refinery complexes and its industry-leading low greenhouse gas footprint is extraordinarily impressive and fascinating to us. And some of us have been working this basin from an infrastructure point of view for well over 30 years. All of these attributes provide further evidence as to why we have seen a number of operators turning their focus away from onshore shale basins, as these basins have seen or will soon see peak production and they have instead started to focus on the Gulf of Mexico, where production is increasing, there is a vast swath of undeveloped acreage and countless new large-scale developments both sanctioned and yet to be sanctioned on the horizon.
Along these lines, we have successfully laid the 105 miles of the sink lateral and remain on schedule and importantly on budget with this project and our CHOPS expansion project, both of which we expect to be ready for service in the second half of 2024. The contracted Shenandoah and Salamanca developments and their combined 160,000 barrels of oil per day of incremental production handling capacity remain on schedule and will be additive to our then base of volumes in 2024. These two new projects, combined with our steady base volumes and increasing inventory of identified subsea tiebacks, provides us with the visibility to generate north of $500 million per year of segment margins starting in 2025. All of this is to say, we remain well positioned to deliver steady, stable and growing cash flows from our offshore pipeline transportation segment for many years to come.
Turning now to our Soda and Sulfur Services segment, our soda ash business generally performed in line with our expectations during the quarter, despite continued weak economic data out of China and the continued increase in new natural production from Inner Mongolia. The combination of these factors is contributing to an increase in apparent export volumes from China, which in turn is applying downward pressure on soda ash prices in these export markets in Asia. In addition to weaker economic data in Asia, we are starting to see slowing economic data both in Europe and in the U.S., most notably in the container glass industry. Given these factors and the anticipation of additional volumes from China, one might reasonably expect to see some level of supply rationalization sooner rather than later, as higher cost synthetic production becomes increasingly uneconomic in Europe and China at today’s prices.
Alternatively, a recovery in global economic activity and a return to historical growth levels, with a focus on the domestic market in China, when combined with the green shoots from the growing demand from lithium and solar panel customers, could also help the soda ash market to balance much quicker than in prior periods of oversupply. It is likely going to be a combination of both supply and demand responses that will help the soda ash market return to a more balanced market than what we’ve seen in the last six months. The ultimate timing of a recovery is somewhat uncertain and it could conceivably take 12 months to 18 months to become tight again, but it undoubtedly will. Accordingly, it remains increasingly important to be at the lower end of the global cost curve during periods of price uncertainty.
All natural producers of soda ash, which only supply approximately 28% of global demand, enjoy this advantage, with operating costs of about half of the costs of synthetic producers, which supply the other 72%, and in general, a significantly smaller environmental footprint relative to synthetic producers. Furthermore, those natural producers with solution mining operations have the absolute lowest cost of production and thus continue to have a competitive advantage over all producers during periods of excess supply and or lower demand. Increasing our exposure to low-cost solution mining was a central investment thesis in our Grainger expansion project and once fully ramped, roughly half of our total production capacity will be from solution mining.
