In general, our NGL storage assets provide warehousing of mixed NGLs, NGL products and petrochemical products in underground wells, which allows for the injection and withdrawal of such products at various times in order to meet supply and demand cycles. Similarly, our terminaling operations provide the inbound/outbound logistics and warehousing of mixed NGLs, NGL products and petrochemical products in above-ground storage tanks. Our NGL underground storage and terminaling facilities serve single markets, such as propane, as well as multiple products and markets. For example, the Mont Belvieu and Galena Park facilities have extensive pipeline connections for mixed NGL supply and delivery of component NGLs. In addition, some of our facilities are connected to marine, rail and truck loading and unloading facilities that provide services and products to our customers. We provide long and short-term storage and terminaling services and throughput capability to third-party customers for a fee.We operate our storage and terminaling facilities to support our key fractionation facilities at Mont Belvieu and Lake Charles for receipt of mixed NGLs and storage of fractionated NGLs to service the petrochemical, refinery, export and heating customers/markets as well as our wholesale domestic terminals that focus on logistics to service the heating market customer base. Our international export project includes our facilities at both Mont Belvieu and the Galena Park Marine Terminal near Houston, Texas. The facilities have export capacity of approximately 7 MMBbl per month of propane and/or butane with the capability to export international grade low ethane propane. We have the capability to load VLGC vessels alongside small and medium sized export vessels. We continue to experience demand growth for US-based NGLs (both propane and butane) for export into international markets.
Across the Logistics and Marketing segment, we own or operate a total of 39 storage wells at our facilities with a net storage capacity of approximately 69 MMBbl, the usage of which may be limited by brine handling capacity, which is utilized to displace NGLs from storage.
The following table details the Logistics and Marketing segment's NGL storage and terminaling facilities at December 31, 2017
(1) Volumes reflect total import and export across the dock/terminal and may also include volumes that have been handled at the Mont Belvieu Terminal.
(2) Exludes six non-owned wells we operate on behalf of Chevron Phillips Chemical Company LLC ("CPC"). An additional well has been drilled and is being prepared for operations. Two additional wells are permitted.
(3) Five of 12 owned wells leased to Citgo Petroleum Corporation under long-term leases.
Our fractionation, storage and terminaling business includes approximately 900 miles of company-owned pipelines to transport mixed NGLs and specification products.