Transient Pressure Behavior of Finite-Conductivity Fractures in Horizontal Wells Considering Interference of Water-Injection Wells

Abstract

Fractured horizontal wells and water-flooding development are effective means to stabilize oil production in low-permeability reservoirs; however, transient pressure behavior analysis based on a single-well testing model ignores the interference effect caused by water-injection wells. With advancements in horizontal drilling technology, multiple-fracture horizontal wells are widely used in tight reservoirs, and researchers have concluded that pressure drops in hydraulic fractures cannot be ignored. In this paper, we present a well testing model that considers the effects of finite-conductivity fractures and the interference of water-injection wells. The analytical solutions were derived based on the source function and superposition principle, and the characteristics of the transient pressure behavior at the bottom hole are analyzed and discussed. The typical pressure curve of our model showed that seven flow regimes exist: wellbore storage stage, transitional flow, first linear flow, fracture interference flow, second linear flow, pseudoradial flow, and interference flow. Furthermore, the results of the sensitivity analysis indicated that the flow regimes are greatly affected by the properties of the fractures and water-injection wells. The length of the fracture mainly affects the transitional flow, first linear flow, fracture interference flow, and second linear flow regimes, whereas the number of fractures predominantly affects the first two stages. The fracture spacing has a significant effect on the fracture interference flow and second linear flow regimes, and the water-injection rate mainly affects the interference flow regime. The well spacing determines when the interference effect occurs. These findings will support more accurate modeling of well production performance considering the impact of water-injection wells. Well test analysis is an effective measure in the process of reservoir development, and it is mainly used to monitor well production performance or estimate the physical parameters of the formation. Currently, multiple-fracture horizontal wells and water-flooding development are widely used in low-permeability reservoirs; however, a single-well test analysis method cannot reflect the reality of communication between production wells and adjacent wells. In this work, we present an interference well testing model that considers the effect of water-injection wells. The transient bottom-hole pressure response under different parameters was studied and analyzed, and the results of this study can be mainly applied in the arrangement of well groups in the development decision stage and adjustments of oil recovery plans in the middle production period. The cases investigated in this study provide several reliable references for engineers in well production management, and may also provide some guidance in further development decisions for oil fields applying multiple-fracture horizontal wells and water flooding.