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Research On Fluid Inclusions Of The Researvoirs In The Upper Paleozoic In The Ordos Basin

Posted on:2005-09-22Degree:MasterType:Thesis
Country:ChinaCandidate:A P FanFull Text:PDF
GTID:2120360125452203Subject:Petrology, mineralogy, ore deposits
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As the main strata of natural gas exploration at current, the Upper Paleozoic reservoirs of the Ordos basin was provided with well-developed riverway sandstones, great thickness of sandstones and multiple gas-bearing formations. It took on gigantic output capacity and wide exploration foreground. In order to acclerate the pace of gas exploration in the researched area, it was essential to develop gas accumulation research. Based on particular research on fluid inclusions of gas reservoirs in the Upper Paleozoic in the Suligemiao and Yulin gas field, the accumulation temperature, accumulation periods and conservation condition of the gas pool were respectively estimated. So the important theoretical evidence for gas exploration was offered.Some primary features of fluid inclusions, such as shape, size, color, abundance ratio, distribution, and phase etc, were observed and recorded. Fluid inclusions were divided into different types according to the features. Combined with diagenesis study, the forming stages of fluid inclusions can be established.A great deal of data of fluid inclusions in autogenetic minerals of different diagenetic stages such as homogenization temperature, melting temperature, salinity, density, and liquid composition etc, were detected. Through using different stages and types of fluid inclusions(singular inclusions , inclusions in autogenetic minerals of the corresponding period, and inclusions in the same kind of autogenetic mineral), these data were analyzed and dealed with.It was made clear that there were three main periods of the filling and accumulation of natural gas in the area, which respectively were 152~141Ma, 123~120Ma and about 110Ma. Geochemistry data indicated that the former two filling event of natural gas were developed in the Suligemiao and Shenmu-Mizhi gas field, the Wushenqi gas field underwent the whole filling history and only one filling event was developed in the Yulin gas field. The results were consistent with tectonic geothermal events in the researched area.The information of fluid inclusions demonstrated the Upper Paleogroundwater of the Ordos basin was dominated by NaCl - H2O system in addition to very few CaCl2 -H2O or NaCl-MgCl2 - H2O systems. The high salinity of NaCl -H2O system reflected the reservoirs in the Upper Paleozoic in the Ordos basin were located in the relatively close circumstance and the migration of fluid seldom occurred. Therefore, this stable hydrodynamic condition could keep the natural gas pool from destructing.
Keywords/Search Tags:the Ordos basin, the Upper Paleozoic, Fluid inclusions, Homogenization temperature, Accumulation periods of gas pool
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