The country's Great South, Canterbury, Reinga/Northland, East Coast basins, along with deep-water possibilities of petroleum acreage, have also attracted significant interest as emerging basins of petroleum potential.Oil production levels currently sit at 21 million barrels (mmbbls) per annum, while natural gas production is 158 billion cubic feet (Bcf) per annum, according to the latest figures provided by EnergyStream. Estimated oil reserves are known to be 180 mmbbls, with the potential to reach 527 to 11,161 mmbls. Gas reserves are known to be 4,600 Bcf, with the potential to reach 11,310 to 67,785 Bcf. In 2011, oil was the nation's fourth-largest export product at a value of $2.2 billion. Potential investment opportunities TAG Oil is a production and exploration company with operations focused exclusively in New Zealand. Over the past three years, the company has recorded substantial oil and gas production and reserve growth through the development of several light oil and gas discoveries. TAG is actively drilling exploration prospects identified across more than 2.9 million net acres of land in New Zealand; in the East Coast Basin, it is aiming to explore and potentially develop unconventional resources that are believed to exist over its acreage. TAG notes that these formations have similarities to North America's Bakken source-rock formation in the successful Williston Basin. Marauder Resources East Coast (TSXV:MES) is a junior player that also has interests in Canada, the Middle East and the Gulf of Aden. It recently announced that its wholly owned subsidiary has been awarded Petroleum Exploration Permit 53806 in the East Coast Basin of New Zealand. Marauder will be the operator of the permit and will hold a 50-percent working interest; the remaining 50 percent will be transferred to an international oil and gas exploration company based in Canada. New Zealand Energy is engaged in the production, development and exploration of petroleum and natural gas assets in New Zealand. Its property portfolio covers approximately 2.27 million acres (including pending permits) of conventional and unconventional prospects in the Taranaki Basin and East Coast Basin of New Zealand's North Island. The company recently provided an update on its activities in the Taranaki Basin that highlights the commencement of continuous production at its Waitapu-2 well and the completion of operations at two wells on its Arakamu site.