Abstract
Salaxing oilfield of Daqing has been developed for more than 40 years and has entered the high water cut late development stage. The reservoirs are large lacustrine luvial delta facies with multi-layers, heterogeneity is serious, watered-out degree of the reservoirs are extremely uneven, remaining oil distribution is complicated too, but its potential to produce oil is still high, and is mainly concentrated in the thick reservoirs of sandstone sediment origin. To produce the remaining oil in the thick reservoirs, the currently used ways are selective perforation, deep profile modification, selective position fracturing etc., and the currently used methods are infill drilling, polymer flooding etc. However, the use of these ways and methods in vertical wells can't completely produce the remaining oil inside the thick reservoirs. This paper provides an example of a successful horizontal well with a horizontal section of 650 m and production rate of nearly 100 t/d, which is drilled in channel sandstone of 7 m (of which the lower part has been watered-out to a medium ~ high degree) with the remaining oil bearing thickness of only 3 m. The key technologies are lateral accretion interlayer prediction technology by detailed reservoir description, accurate remaining oil description to avoid the watered-out section of the horizontal well, and optimally perforation technology for horizontal well. This indicates that drilling horizontal wells in Salaxing oilfield of Daqing can increase the oil recovery of channel sandstones reservoirs with extra high water cut.
