Details of the abstract
Title of paper | Electromagnetic technology for prospecting unconventional hydrocarbon resources |
List of authors | Yan Liangjun |
Affiliation(s) |
1. Key Laboratory of Exploration Technologies for Oil and Gas Resources (Yangtze University), Ministry of Education, China, 430100. 2. Cooperative innovation center of Unconventional oil and gas, Hubei, China 3. Key Laboratory of Geophysical prospecting, CNPC |
Summary | Unconventional oil and gas (normally tight gas and oil, shale gas and oil, coal seam gas, natural gas hydrate, etc.), which generally have the characteristics of source-reservoir symbiosis, are widely distributed. Still, their high-quality reservoirs have large burial depths, small targets, complex electrical properties, and considerable inhomogeneity, making their a great challenge for electromagnetic (EM) exploration to detect them. In recent decade, A series of achievements have been made in the field of EM exploration of unconventional oil and gas worldwide, including the EM response mechanism of unconventional reservoir rocks, new methods and technologies in controlled-source EM exploration on land, identification and evaluation methods for oil and gas using EM parameters. These technologies have been successfully applied in unconventional oil and gas exploration and development with good effect and have been recognized by petroleum geology and development circles. Firstly, this paper introduced the complex resistivity characteristics of organic-rich shale, tight sandstone, and dolomite in southern China occurring in low porosity and permeability reservoirs, and discovered that organic-rich shale has the characteristics of low resistivity and high polarization. At next, an IP model for the shale reservoirs is established. Based on the mechanism of source-reservoir symbiosis in shale reservoirs, the identification mode for the sweet spot is proposed. It is then proved this paper that there exist a good petrophysics foundation for the EM exploration in the field of shale gas exploration and development. Secondly, there has been a research focus on how to use the multiple IP parameters, such as resistivity and polarizability, to estimate the characteristic parameters of the sweet spot of reservoir. The prediction method based on IP model for the parameters of reservoir is introduced. Thirdly, there is an outspring of the controlledsource EM exploration methods for unconventional oil and gas exploration, such as Wide Field Electromagnetic Method (WFEM), Wire-less Electromagnetic Method (WEM), Time-Frequency Electromagnetic Method (TFEM), Long Offset and Window Transient Electromagnetic Method (LowTEM) and Focused Source Electromagnetic Method (FSEM). These methods and technologies share a common feature of using a long wire source, with high-power, large current multi-waveform transmission, multi-component array acquisition and hybrid processing and inversion. Therefore, not only the signal-to-noise ratio, exploration depth, resolution and reliability, but also the efficiency, resolution, cost and adaptability have been significantly improved, making these methods able to deal with the geology problems in the exploration and development of unconventional oil and gas under complex conditions. Finally, several cases are given to indicate the apparent application effects of the new methods and technologies of controlled-source EM method in unconventional oil and gas exploration, sweet spot detection, fluid identification, fracturing monitoring, and at the same time, look into the broad application prospect of EM methods in the exploration and development of unconventional oil and gas. However, there are still plenty of unsuccessful cases. It is a long way to go in the effective application of EM methods in unconventional oil and gas exploration and development. Therefore, more achievements are expected to be made, especially on the EM response mechanism of unconventional oil and gas reservoirs, 3D high spatial and temporal density data collection technology under complex geological and topographical conditions, fast, stable and reliable high-precision inversion and imaging methods with constraints based on prior logging and seismic data, reservoir parameters prediction method based on refined IP model. |
Session Keyword | 3.0 Exploration, Monitoring and Hazards |
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