Chapter 1 Purpose and Significance of Research1.1 ConceptShale gas is a type of unconventional natural gas, which is trapped or collected in dark shale or carbon rock. The rock layer has low permeability and low porosity, meaning that the best way to achieve this appeal is by fracturing to improve connectivity and porosity. Shale gas deposits are mainly located in North America, Central Asia, China, Latin America, the Middle East, North Africa, Russia and other countries and regions. The United States and Canada are only two countries that have significant shale gas production.1.2 HistoryIn 1821, shale gas was first mined underground as an energy resource in Fredonia, New York. Shale gas technology has been developed since the 1930s, and the first shale gas development well was drilled in 1947. The shale gas industry was established in the 1970s; During that time, the U.S. government had to finance shale gas to address declining capacity for natural gas. Thanks to this situation and investment, some inevitable technologies are developed such as: directional and horizontal well technology, seismic imaging technology and large hydraulic fracturing technology. In 1982, the federal government invested billions of dollars in research institutes in this field. During the 1980s, the federal government passed an energy law, which provides tax incentives or other preferential policies for the energy industry. In 1986, with several private gas companies, the US Department of Energy successfully constructed the first horizontal shale gas well with air drilling technology. In the 1980s and 1990s, the federal government adopted additional tax incentives on unconventional gas by 29 to encourage… middle of paper… influence on migration, aggregation, and reservoir formation. There are two aspects. On the one hand, the development of cracks in shale can significantly improve reservoir permeability; it can also increase the overall amount of free gas; and can promote shale gas migration as a drainage system. 1.3.5 Thickness and Moisture To ensure sufficient organic matter and plenty of space to form commercial shale gas reservoirs, the actual thickness of the shale rock is needed. The thickness of the shale gas reservoir controls the economic benefits of shale gas reservoirs. The greater the effective thickness, especially the greater the continuous effective thickness, the greater the total amount of organic matter, the greater the degree of shale gas enrichment. The thickness limitation of shale gas can be reduced with increasing maturity of organic carbon content.