Formation Temperature of Dawsonite from Qingshankou Formation in the Honggang Oilfield, Southern Songliao Basin

Key words: 
• Honggang Oilfield

Abstract: This article mainly use the Hong143 and Hong146 well that rich in dawsonitebearing sandstones as reaearch objiects.According to the analysis of conventional thin sections, alizarin redstaining, SEM, INCA energy spectromete, microthermometry , the diagenetic paragenesis succession of dawsonitebearing sandstones, in particular, the homogenization tempreature of fluid inclusion have been studied in detail. The diagenetic paragenesis of the Honggang Oilfield is clay minerals→secondary quartz overgrowths→calcite→dawsonite→ankerite→quartz healing microfracture. On the basis of intensive microthermometry, the peak of the homogenization tempreature is 110～120℃ in the calcite; while 130～140℃ in the quartz healing microfracture. The formation temperature of dawsonite is between calcite and quartz healing microfracture, which is 120～130℃. Comparing with research results at home and abroad, the formation temperature of dawsonite that is transformed by magma is relatively low , which is 25～150℃. The formation temperature of dawsonite that appeared in the inclusion as daughter mineral is relatively high,which is 250～340℃. The dawsonite in the southern Songliao Basin belong to the first situation, the formation temperature is relatively low, which is 120～130℃. Scanning electron microscopy and energy spectrum analysis shows that the dawsonite of Hong gang oil filed (The formation of temperature between 120～130℃) is mainly needlelike, the chemical composition is rich in Si, poor in Na, Al and O; the dawsonite of Wuerxun Depression (The formation of temperature between 78.56~115.02℃) is mainly columnar pin, chemical composition is rich in Na, Al and O, poor in Si.