This paper presents an integrated experience in injection horizontal wells (HW) using with a varied well completion type, including multi-stage hydraulic fracturing. The historical path of development systems: from multi-row with directional wells (DW) and low rigidity of the reservoir pressure maintenance system to oriented dispersed waterflood systems with HW are considered. Based on the data of hydrodynamic studies of wells, Hall plots, well interference analysis, well tests results, the development self-induced hydraulic fracturing in HW was proved. In the low-permeability reservoirs the achievement of the planned injectivity is determined by the presence of a self-induced hydraulic fracture, which is initiated when the bottomhole pressure exceeds the formation fracture pressure. It is noted that with an increase reservoir pressure, a decrease in the self-induced hydraulic fracturing effect and degradation of the fracture is observed. To assess the horizontal wells effectiveness, a comparison was made of the starting parameters and dynamics of the injection HW vs. DW. The results of studies of HW injectivity profiles are analyzed, potential reasons for the uneven injection distribution across hydraulic fracturing ports are considered. The areas of injection HW applicability in different geological and physical conditions, that is, when the injection HW allows a complete replacement of two DW to achieve the planned injectivity and injection ratio, as well as the sweep efficiency in linear development systems, have been identified. Recommendations on the further research program for horizontal injection wells and on improving the efficiency of this waterflooding method were given. The study is important due to the constant increasing technological complexity of well completion and the HW increasing share.
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