Identification of Horizontal Fracture Morphology and Flow Characteristics in Shallow Oil Reservoirs

doi:10.3969/j.issn.1006-6535.2024.06.011

Abstract

Abstract: Aiming at the problem of unclear understanding of fracture morphology and water flooding seepage law after 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 characteristics of a single horizontal fracture under real formation conditions were simulated by large-scale true triaxial laboratory experiments.Based on the Newman product method and Green's function concepts,a numerical model of elliptical 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 distances 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 production control.This research can provide technical references for water injection development in shallow oil reservoirs.

Key words: shallow oil reservoir, horizontal fracture, fracture morphology, permeability characteristics, physical simulation, numerical model

CLC Number:

TE357

Shi Tiaotiao, Shi Lihua, Wu Xiaoting, Tong Changbing, Shen Zhenzhen, Cai Jianchao. Identification of Horizontal Fracture Morphology and Flow Characteristics in Shallow Oil Reservoirs[J]. Special Oil & Gas Reservoirs, 2024, 31(6): 91-99.

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