Fluid-Solid Coupled Production Model of Fractured Horizontal Well in Glutenite Tight Oil Reservoirs

Abstract

ABSTRACT Clarifying the seepage mechanism and production decline law of fractured horizontal wells in glutenite reservoirs is crucial for guiding fracturing design, optimizing the production system, and realizing efficient reservoir development. In this paper, a production model suitable for fractured horizontal wells in glutenite tight oil reservoirs was established, based on the principle of fluid-solid coupling and comprehensive consideration of the characteristics of reservoir rock deformation and permeability stress sensitivity during production. An example application was used to verify the accuracy of the model, and the factors affecting production were discussed. The research results demonstrate that the model can reflect the dynamic change characteristics of the stress field and permeability during the production process. The production differential pressure must be controlled within the critical production differential pressure to avoid shear compaction in some formations near the wellbore, which could greatly reduce permeability and production. Among the fracturing engineering parameters, fracture spacing mainly affects the early linear seepage of the fractured horizontal well, whereas fracture half-length mainly affects the mid-late radial seepage. Increasing the fracture half-length has a more significant impact on increasing the long-term cumulative production of fractured horizontal wells in glutenite reservoirs. INTRODUCTION The Mahu Oilfield is situated in the Mahu Sag of the Junggar Basin, Xinjiang, with geological reserves of 1.24 billion tons and proven reserves of 520 million tons. It is currently the world's largest glutenite tight oil reservoir (Anon, 2018; He and Zhang, 2017). Thanks to the development of large-scale volumetric fracturing technology for horizontal wells, significant breakthroughs have been made in production in this area, making it the primary region for increasing reserves and production in the Xinjiang Oilfield (Li et al., 2020). However, glutenite tight reservoirs typically possess poor physical properties, strong heterogeneity, and weak matrix fluid supply capacity (Gao, 2022; Hao et al., 2021). Consequently, the pressure attenuation speed is often rapid after fracturing in certain blocks, resulting in insufficient continuous production capacity. Therefore, understanding the seepage mechanism and production decline law is critical for guiding fracturing design, optimizing the production system, and achieving efficient development of glutenite tight oil reservoirs.