Abstract:

To address the issue of interwell interference caused by adjacent well fracturing and development adjustments in shale gas reservoirs, existing dynamic evaluation methods for well groups based on single wells or those ignoring fracture network connectivity are inadequate. A well test analysis model for shale gas well groups, incorporating the connectivity of fracturing network, was developed based on a variable conductivity fracture model. By discretizing the fracture network, the model equation of multi-stage fracturing well groups was transformed into linear equations and the bottom-hole pressure solution of well groups was obtained. The bottom-hole pressure solution of the well groups was compared and validated using the finite volume numerical method. Typical characteristic curve diagrams of bottom-hole pressure, both with and without connected fractures, were established. Application examples of four wells on two platforms in the Fuling shale gas field were provided. The results showed that: ① Production wells had bilinear flow (1/4 stage), linear flow (1/2 stage), unsteady crossflow, and boundary quasi-steady flow stages, while non-production wells rarely had bilinear or linear flow stages. ②Under both connected and unconnected fractures, the bottom-hole pressure solution of the well group calculated by the finite volume numerical method was entirely consistent with that calculated by the method proposed in this paper. ③ The interpretation and evaluation results of measured data from four wells on two platforms in the Fuling shale gas field were consistent with field observations, verifying the reliability and practicality of the proposed method. The findings provide technical support for calculating shale gas reservoir parameters and fracturing parameters, and evaluating interwell connectivity.

Key words: shale gas, multi-stage fracturing, fracture connectivity, well group, well test analysis