Multi-well studies to identify the causes of sudden water breakthrough to producers

Introduction. The aggressive injection pressure resulting in spontaneous hydraulic fractures in injection wells improves the process of maintaining reservoir pressure in low-permeability reservoirs. However, the instability of fracture development may adversely affect field development by disrupting the uniformity of displacement, creating a hydrodynamic connection between adjacent areas, and leading to uncontrolled water breakthrough to producing wells.
Aim. The goal of the study is to identify and comprehensively analyze the causes of the sharp water production increase in producing wells following the implementation of injection pressures with the induced fracture in an injection well, using the example of a field with several licensed areas.
Materials and methods. This work utilized pressure transient analysis and production logging interpretation results, petrophysics, tracer tests, and 6K analysis of the produced fluid composition. In addition, analytical modeling was applied to evaluate parameters such as the formation bedding angle, and a calculation of spontaneous hydraulic fracture propagation was performed.
Results. Data analysis allowed for the consideration of all potential causes of the observed phenomenon and confirmed the existence of well interference between license areas. It was established that the spontaneous hydraulic fracture, occurring in injection wells on an adjacent area, led to the formation of an extensive fracture that crossed the boundaries of the licensed areas and facilitated the influx of water into the producing wells.
Conclusions. The study revealed that for a correct interpretation of the production logging, the formation bedding angle should be taken into account. It also emphasized the importance of a comprehensive analysis of neighboring areas prior to conducting any operations. The risk of direct water breakthrough from injectors to producers through spontaneous hydraulic fracture, even over large distances, has been confirmed on a low permeable asset.

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