Low permeability thin oil layers have become the main object for waterflooding production in extreme high water cut stage in Changyuan area

Daqing oil field.However

conventional methods

such as well pattern infilling and layer-specific water injection

could get no satisfying effect.Therefore

a method of independent development of low permeability thin oil layers is put forward by taking into account features of these low permeability thin oil layers and technologies of layered hydraulic fracturing.Two kinds of development models are suggested

and one of the models designs how water wells perforate reservoir zones depending on the number and pattern of oil wells that perforate low permeability thin oil layers only

the other one designs how oil wells perforate zones depending upon the number and patterns of water wells that perforate low permeability thin oil layers only.Then

the recovery of these two modes are compared by waterflooding physical simulation experiments with multi-layer artificial casting cores.The productivity model of layered fractured vertical well is deduced considering the threshold pressure gradient and horizontal fractures in shallow reservoirs

and the technology limits are calculated and analyzed for the independent development of low permeability thin oil layers.The results show that the first model will get more recovery than the second one

and the technical limit of spacing is about 228 m

the economic limit of thickness is 2 m.With the increasing of low permeability thin oil layers thickness to total perforated thickness ratio

recovery declines firstly and then remained stable

and rises rapidly finally.Field application shows that the average well production is 3.7 tons/day under the independent development of low permeability thin oil layers

its development effect is better than tertiary well pattern infilling.