Injection Profiling in Polymer Injectors in Daqing Oilfield

摘要

Daqing oilfield is implementing large-scale polymer floodingrnto increase oil recovery. With the increasing of injection fluidrnviscosity, some traditional injection profiling methods lostrntheir validity. Three methods developed for polymer injectionrnprofiling have been used in Daqing oilfield.rnAn electromagnetic flowmeter was designed for water/rnpolymer injection profiling in injectors without separate-zonerninjection mandrel at zones. It can survey in both continuousrnand stationary modes. It is verified that the logging tool stringrnalso works perfectly in Alkaline/Surfactant/Polymer injectors.rnIt has been successfully applied more than 2400 runs forrnpolymer injection profiling.rnOxygen activation tools have been applied for measuringrnwater or polymer flow behind tubing and even casing. Thernlogging tool widely used in Daqing oilfield consists of casingrncollar locater, a neutron generator, three gamma-ray detectors,rnand relevant circuits. Its measurement error is less than 5 % inrnthe flowrate range from 20 m3/d (130 B/D) to 400 m3/d (2520rnB/D) of flow in the annular space between 73 mm (2-7/8 in)rnOD tubing and 140 mm (5-1/2 in) OD casing. It is applied 350rnruns each year, including 250 runs for polymer injectionrnprofiling.rnTracer logging with correlation arithmetic has been appliedrnmore than 500 times in polymer injectors. The method utilizesrngamma-ray detectors to measure flow velocity after a slug ofrnradioactive tracer has been ejected into borehole. The methodrnis preferred for low-injection separate-zone polymer injectors.rnExperimental results and field examples have proved thatrnelectromagnetic flowmeter, oxygen activation tool, and tracerrnlogging with correlation arithmetic are suitable for polymerrninjection profiling in Daqing oilfield.