Waterflood-assisted oil recovery with sulfate-spiked seawater would cause incompatibility scaling in carbonate reservoirs and reduce economic benefits.This research investigated the benefits of polyphosphate compounds...Waterflood-assisted oil recovery with sulfate-spiked seawater would cause incompatibility scaling in carbonate reservoirs and reduce economic benefits.This research investigated the benefits of polyphosphate compounds in reducing scaling potential as well as its effect on oil recovery when mixed in high sulfate flood water.Severity of scaling potential of sulfate-spiked water in a carbonate reservoir environment was measured,followed by systematic screening of a polyphosphate compound,which successfully inhibited the sulfate scale precipitation at concentration as low as 100 ppm.The new formulation(seawater with four times sulfate and phosphate,SW4 SP)was evaluated and compared with benchmark formulation(modified seawater with four times sulfate,SW4 S).Contact angle,ζ-potential and drainage studies show that SW4 SP changed the rock wettability from oil wet to water wet to a larger degree compared to SW4 S.Improved recovery efficiency of SW4 SP was confirmed through a set of core flooding studies in the tertiary and quaternary flood modes.Whereas SW4 S recovered 7.7%of original oil in place(OOIP),SW4 SP recovered about 8%of OOIP in the tertiary mode under approximately identical flow conditions.Flooding with SW4 SP in the quaternary mode following a tertiary flood with SW4 S on the same core resulted in 1.7%additional oil recovery,showing improved efficiency of the new flood water formulation.展开更多
The removal efficiency of heavy metals from offshore muds is enhanced in the presence of generated chlorine gas (Cl2). The tests showed a high removal efficiency of heavy metals at the anode end of cores after 24 hour...The removal efficiency of heavy metals from offshore muds is enhanced in the presence of generated chlorine gas (Cl2). The tests showed a high removal efficiency of heavy metals at the anode end of cores after 24 hours of EK application. In the initial tests, high electrokinetic flow potential was achieved;however, high levels of chlorine gas were produced in the high-salinity environments. The process was improved by controlling and maintaining a certain fraction of the chlorine gas (Cl2) in place. The pH was controlled by the chlorine gas maintained in-situ and transported from the anode to cathode. The transports of four heavy metals were evaluated in this study. The chlorine gas can have two impacts on the transport of metals in the system. One is to oxidize the metal ions to a higher oxidation state and the second is to form chloride complexes, which have higher mobility in the system. Determination of oxidation state and the subsequent metal chloride complex are left for future research.展开更多
文摘Waterflood-assisted oil recovery with sulfate-spiked seawater would cause incompatibility scaling in carbonate reservoirs and reduce economic benefits.This research investigated the benefits of polyphosphate compounds in reducing scaling potential as well as its effect on oil recovery when mixed in high sulfate flood water.Severity of scaling potential of sulfate-spiked water in a carbonate reservoir environment was measured,followed by systematic screening of a polyphosphate compound,which successfully inhibited the sulfate scale precipitation at concentration as low as 100 ppm.The new formulation(seawater with four times sulfate and phosphate,SW4 SP)was evaluated and compared with benchmark formulation(modified seawater with four times sulfate,SW4 S).Contact angle,ζ-potential and drainage studies show that SW4 SP changed the rock wettability from oil wet to water wet to a larger degree compared to SW4 S.Improved recovery efficiency of SW4 SP was confirmed through a set of core flooding studies in the tertiary and quaternary flood modes.Whereas SW4 S recovered 7.7%of original oil in place(OOIP),SW4 SP recovered about 8%of OOIP in the tertiary mode under approximately identical flow conditions.Flooding with SW4 SP in the quaternary mode following a tertiary flood with SW4 S on the same core resulted in 1.7%additional oil recovery,showing improved efficiency of the new flood water formulation.
文摘The removal efficiency of heavy metals from offshore muds is enhanced in the presence of generated chlorine gas (Cl2). The tests showed a high removal efficiency of heavy metals at the anode end of cores after 24 hours of EK application. In the initial tests, high electrokinetic flow potential was achieved;however, high levels of chlorine gas were produced in the high-salinity environments. The process was improved by controlling and maintaining a certain fraction of the chlorine gas (Cl2) in place. The pH was controlled by the chlorine gas maintained in-situ and transported from the anode to cathode. The transports of four heavy metals were evaluated in this study. The chlorine gas can have two impacts on the transport of metals in the system. One is to oxidize the metal ions to a higher oxidation state and the second is to form chloride complexes, which have higher mobility in the system. Determination of oxidation state and the subsequent metal chloride complex are left for future research.
