Chinese Shale Gas Exploration Started Officially and Primary Results Achieved

Shale gas is a new, clean and efficient unconventional oil and gas resource, and it has become a new highlight of global oil and gas exploration and exploitation. In recent years, the Ministry of Land and Resources of The People＇s Republic of China launched the program Investigation and Evaluation of China Shale Gas Resources and Favorable Areas Preferred, which has evaluated the shale gas resource potential and selected potential areas for exploration and exploitation.

Present Situation of China's Shale Gas Exploration and Development

In recent years,with China＇s continuous investment in shale gas exploration and the continuous efforts of scientific workers,China’s shale gas exploration and development has achieved leap-forward development.In2011,China＇s State Council approved shale gas as a new mineral resource.In 2014,shale gas was first proved at geological reserves of 106.8 billion m^3.

Shale gas exploitation with supercritical CO_2 technology

This paper analyzes the physicochemical properties of supercritical C02, the characteristic of shale gas and shale gas reservoirs. The technologies of drilling, production, fracturing using the supercritical CO2 in shale gas explo- ration are proposed, to increase the penetration rate, decrease the damage to formation while fracturing, and enhance the recovery of shale gas. It is believed that the huge economic benefits of shale gas exploration with the supercritical CO2 fluid will be obtained, and it also can initiate a new technology field of CO2 in the petroleum engineering.

Relationship Between Electrical Properties and Sedimentary Environment of the Longmaxi Formation Shale,Southern Sichuan

The Lower Silurian Longmaxi Formation in the south of Sichuan is a key player in the exploration and development of shale gas in China.Due to a highly complex topographic area,electromagnetic methods(EM)become important exploration means in this area.Many studies have been conducted on the shale mineral composition and electrical properties of shale,however,the correlation between sedimentary environments and the electrical properties of shale remain poorly understood.The electrical properties and sedimentary environment of the organic-rich shale of the Longmaxi Formation have been studied by means of X-ray diffraction,organic geochemistry,scanning electron microscopy and complex resistivity measurements.The discovered high quartz content of the Longmaxi Formation shale results in low resistivity.Deep-water shelf biogenic quartz contributes lower resistivity more than that of shallow-water terrigenous quartz.The deep-water anoxic and organic sedimentary environment led to major enrichment of pyrite,leading to a high polarization effect in shale.We present the correlation between the lithofacies types and electrical properties of Longmaxi Formation.The mixed siliceous shale lithofacies is the most favorable among the three lithofacies,which is characterized by high total organic carbon(TOC)content,high brittleness mineral content,high polarization and low resistivity("three high and one low").This feature is an effective identification of shale gas reservoirs by electromagnetic prospecting.Our study can provide constraints on electrical parameters of rocks for electromagnetic"sweet spot"exploration of shale gas,and so this has important geological significance to shale gas exploration and development.