WorldWide Drilling Resource

A New Frontier for South Korea Compiled by Caleb Whitaker, Associate Editor, WorldWide Drilling Resource ® South Korea doesn’t have a rich geothermal history because the country does not have high enthalpy geothermal energy sources related to volcanic or tectonic activities; instead, the geology of Korea is characterized by old formations of very thin sedimentary layers. However, there are some regions which deviate from the norm, showing a high geothermal gradient. Pohang is one of these regions, reaching nearly 360ºF (180ºC) at a depth of three miles. For compar- ison, a typical volcanic area reaches temperatures over 300ºF (150ºC) at a depth of almost a mile. The Pohang Enhanced Geothermal Systems (EGS) project began in 2010, as the first of its kind in Korea, with the hopes of producing one megawatt (MW) of electricity. The project is run by a consortium of six industry, research institute, and university research teams and fi- nanced by sources from South Korea. The site will be available for “demonstration of soft stim- ulation treatments of geothermal reservoirs” (DESTRESS) tests, performed by the DESTRESS consortium. The two scheduled tests will be complementary and add great value to the project. Since there were not any deep drilling operations in South Korea prior to the project, the drilling rig utilized was pur- chased by project manager NEXGEO Inc., from the Chinese company Guanghan Jincheng Petroleum Machinery Co., Ltd., who also contracted all the crews to op- erate the drilling rig. The rig used was rated for drilling to 16,400 feet, making it sufficient for drilling the wells in Pohang. The project was divided into two stages. In the first stage, covering the first two years, geothermal exploration at the site was conducted, involving drilling to a depth of nearly two miles to figure out the geology of the area and find tem- peratures in excess of 210ºF (100ºC). The second stage was devoted to com- pleting the geothermal system to a depth of just over three miles, which included deep drilling, directional drilling, hydraulic stimulation, and circulation tests. Drilling on the first well started in 2012, reaching a depth of nearly 7400 feet and temperatures over 210ºF (100ºC) at the bottom of the well. The following year, the well was enlarged to the target depth of nearly 15,000 feet. In 2014, drilling of a second well to the same target depth was commenced, then completed the following year with directional drilling. The 1.2-MW project is expected to pro- vide electricity to an estimated 1000 households as early as this year. Upon the first successful supply of geothermal electricity, officials will raise an additional $80 billion through a power plant consor- tium to expand the current facility for the purpose of generating 6.2 MWs by 2019. The Pohang EGS project drill site, Courtesy of DESTRESS. 26 JUNE 2017 WorldWide Drilling Resource ®