Identification of Horizontal Fracture Morphology and Flow Characteristics in Shallow Oil Reservoirs
Aiming at the problem of unclear understanding of fracture morphology and water flooding seepage law af-ter fracturing in shallow reservoirs,the Chang 6 Reservoir in the eastern area of Yanchang of Ordos Basin was taken as the research object.The fracture morphology was identified by laboratory experiments of fracture pressure gradient and instantaneous pump-off pressure.The three-dimensional flow pressure and streamline distribution characteris-tics of a single horizontal fracture under real formation conditions were simulated by large-scale true triaxial labora-tory experiments.Based on the Newman product method and Green's function concepts,a numerical model of ellipti-cal horizontal fracture considering fracture skin effect and wellbore storage effect was established.This model reveals the impact of fracture morphology,fracture distribution location,and permeability anisotropy on horizontal fracture flow characteristics.The research indicates that the pressure drop across horizontal fractures shows an asymmetric distribution along the horizontal direction,with longer propagation distances along the major axis and shorter dis-tances along the minor axis.Fracture morphology,permeability anisotropy and fracture distribution position have great influence on bottom hole pressure and fracture flow at the initial stage,but have little influence on horizontal fracture flow at the later stage.Building on these findings,a development mode of staggered bottom water injection is put forward.Field application demonstrates significant enhancement in oil recovery and terrific effects on water pro-duction control.This research can provide technical references for water injection development in shallow oil reser-voirs.
shallow oil reservoirhorizontal fracturefracture morphologypermeability characteristicsphysical sim-ulationnumerical model
万方数据
维普
