Influence of Injection Induced Fractures Along Horizontal Wells with ICDs During Subsurface Cold Fluid Injection
Authors: Hu Jinchuan , Sharma Mukul 
Published: August 2024

Injection Induced Fractures (IIFs) are often formed during subsurface fluid injection. Reservoir cooling caused by the injection of cold fluids can reduce the fracture gradient significantly and exacerbate the problem. Uncontrolled IIFs can result in unexpected problems, such as non-uniform injection, poor oil recovery, fault activation, and even earthquakes. By redistributing the injected flow along the wellbore, Inflow Control Devices (ICDs) can significantly influence oil recovery. In this study, a fully coupled reservoir-fracture-wellbore simulator is applied, (a) to study changes in stress during subsurface cold-water injection through horizontal wells with ICDs, and (b) to study the influence of growing IIFs on the distribution of injected fluids. We model a complex wellbore with ICDs and couple it with reservoir flow. It allows dynamic fracture initiation and propagation based on the dynamic stress field accounting for thermo-poro-elasticity, and both internal and external filtration caused by particle plugging. Different injection conditions are simulated. The results show that the rock stress along the horizontal injectors significantly decreases as the cold fluid is injected and this leads to fracture propagation. The application of ICDs significantly influences the growth of IIFs, and proper ICD design is needed to control and prevent unexpected thief zones.

1. INTRODUCTION

Even after decades of research, the issue of injection-induced fractures (IIFs) often remains underemphasized in the modeling of subsurface fluid movements. This lack of focus can introduce significant inaccuracies and elevate the risk of premature water or gas breakthroughs, reduced efficiency in oil extraction, the initiation of faults, and possibly even seismic occurrences. In response, the adoption of Advanced Well Completions (AWCs), notably Inflow Control Devices (ICDs), is growing to better regulate injection profiles within intricate well systems. The principal goal of this research is to use an integrated simulator for the reservoir, fracture, and wellbore that improves our understanding of ICD implementation. This will enable us to more accurately control water injection into specific reservoir areas, thereby reducing the likelihood of seismic activity and the extension of fractures beyond intended zones.

1.1. Advanced Well Completions (AWCs)

AWCs are becoming a more widely adopted suite of technologies in oil and gas operations, having been implemented in a multitude of wells to adjust the flow profiles in either production or injection wells, as noted by Muradov (2018). Within the spectrum of AWC technologies, Flow Control Devices (FCDs) are specifically used within the intervals designated for production or injection. Additional measures like annular flow isolation, gravel packs, and liners are often deployed in conjunction to manage sand and enhance overall well efficiency. The relationship between the pressure drops and flow rate is quadratic, as expressed in Equation 1, facilitating more even inflow or outflow profiles across the completion. FCDs are differentiated based on their operational mechanism into three categories: passive (with a fixed restriction), active (featuring controllable and adjustable restriction), and autonomous (designed to automatically adjust to block unwanted fluids). Although with different designs, the pressure drops across most of them is governed by: