Geological reserves of oil-water transition zone(OWTZ)in low-permeability reservoirs have been considered as uneconomical resources because of high water cut and low abundance.Though the OWTZ may account for 30%-50%of...Geological reserves of oil-water transition zone(OWTZ)in low-permeability reservoirs have been considered as uneconomical resources because of high water cut and low abundance.Though the OWTZ may account for 30%-50%of a reservoir,it has not been paid more attentions yet.The average oil saturation of the OWTZ is about 35%,which is equal to that of a reservoir after water flooding.Currently,CO_(2) flooding is an effective technique for residual oil recovery after water flooding,which could reduce the residual oil saturation greatly.Therefore,it is of significance for the EOR of the low-permeability reservoir if the CO_(2) flooding could be successfully applied in the OWTZ.In this study,a method based on a long core to simulate distribution of oil saturation in OWTZs is set up in the laboratory using bidirectional saturation.In order to investigate CO_(2) flooding characteristics in OWTZs,experiments are carried out on 3 sets of initial oil saturation,and the recoverable reserves of the OWTZ and its contribution to the EOR are calculated based on the WJ reservoir in the Jilin Oilfield,China.展开更多
Carbonate cemented zones are normally adjacent to the top overpressured surface in the central Junggar Basin,NW China.Stable carbon and oxygen isotopic compositions and petrological investigations of carbonate cements...Carbonate cemented zones are normally adjacent to the top overpressured surface in the central Junggar Basin,NW China.Stable carbon and oxygen isotopic compositions and petrological investigations of carbonate cements in the carbonate cemented zones indicate that:(1)carbonate cements are composed dominantly of ferrocalcite,ferroan dolomite,and ankerite;(2)carbonate cements are formed under a high temperature circumstance in the subsurface,and organic fluid migration has an important effect on the formation of them;and(3)carbon and oxygen ions in the carbonate cements migrate from the underlying overpressured system.This suggests that the occurrence of carbonate cemented zones in this region results from multiple phases of organic fluid expulsion out of the overpressure compartment through geological time.This study provides a plausible mechanism of the formation of carbonate cemented zones adjacent to the top overpressured surface in the clastic sedimentary basins,and has an important implication for understanding the internal correlation between the formation of carbonate cemented zones adjacent to top overpressured surface and geofluids expulsion out of overpressured system.展开更多
基金The work was supported by the program of New Technologies and Methods for Oil and Gas Field Development(2016A-09).
文摘Geological reserves of oil-water transition zone(OWTZ)in low-permeability reservoirs have been considered as uneconomical resources because of high water cut and low abundance.Though the OWTZ may account for 30%-50%of a reservoir,it has not been paid more attentions yet.The average oil saturation of the OWTZ is about 35%,which is equal to that of a reservoir after water flooding.Currently,CO_(2) flooding is an effective technique for residual oil recovery after water flooding,which could reduce the residual oil saturation greatly.Therefore,it is of significance for the EOR of the low-permeability reservoir if the CO_(2) flooding could be successfully applied in the OWTZ.In this study,a method based on a long core to simulate distribution of oil saturation in OWTZs is set up in the laboratory using bidirectional saturation.In order to investigate CO_(2) flooding characteristics in OWTZs,experiments are carried out on 3 sets of initial oil saturation,and the recoverable reserves of the OWTZ and its contribution to the EOR are calculated based on the WJ reservoir in the Jilin Oilfield,China.
基金supported by the Important National Science&Technology Specific Projects(Grant No.2008ZX05001)Scientific Development Projects of Petrochina Company Limited(Grant No.2008B-0100)+2 种基金the Doctoral Education Program Fund of Ministry of Education,China(Grant No.20060491505)American Association of Petroleum Geologists Grants-in-Aid Foundation ProgramNational Natural Science Foundation of China(Grant Nos.40739904,40902039)
文摘Carbonate cemented zones are normally adjacent to the top overpressured surface in the central Junggar Basin,NW China.Stable carbon and oxygen isotopic compositions and petrological investigations of carbonate cements in the carbonate cemented zones indicate that:(1)carbonate cements are composed dominantly of ferrocalcite,ferroan dolomite,and ankerite;(2)carbonate cements are formed under a high temperature circumstance in the subsurface,and organic fluid migration has an important effect on the formation of them;and(3)carbon and oxygen ions in the carbonate cements migrate from the underlying overpressured system.This suggests that the occurrence of carbonate cemented zones in this region results from multiple phases of organic fluid expulsion out of the overpressure compartment through geological time.This study provides a plausible mechanism of the formation of carbonate cemented zones adjacent to the top overpressured surface in the clastic sedimentary basins,and has an important implication for understanding the internal correlation between the formation of carbonate cemented zones adjacent to top overpressured surface and geofluids expulsion out of overpressured system.
