Simulation of Proppant Placement Efficiency at the Intersection of Induced and Natural Fractures

Abstract

ABSTRACT: The intersection of the pre-existing natural fractures (NF) with the hydraulic fractures (HF) forms a complex fracture network, which allows for increased well productivity. However, the complex fracture geometry may adversely affect the proppant placement and its transportation inside the fractures. The study reports the results of the Lattice numerical simulations of proppant placement at the intersection of fractures. Sensitivity analysis was performed to investigate the effect of pre-existing fracture friction angle, angle of approach as well as differential horizontal stress on HF-NF interaction mechanisms and proppant transport and placement. The results present the effect of these parameters on proppant transport and placement in NF. 1. INTRODUCTION Hydraulic fracturing (HF) is a commonly used stimulation technique that essentially consists of generating fluid-driven fractures in the reservoir to allow the flow of oil and gas into the wellbore with the goal of increasing reservoir conductivity (Michael J. Economides, 2000). However, this process can be more complex in naturally fractured formations (Boualam et al., 2019; Alexeyev et al., 2017; Djezzar et al., 2019, 2020; Djezzar et al., 2019; Djezzar et al., 2019b, 2019a) due to the possibility of intersection of induced fractures with the natural fractures. Crossing, arresting and opening are the three interaction mechanisms when HF intersects a natural interface (Kolawole & Ispas, 2020). The fracture network development leads to increased fracture conductivity (Djezzar & Boualam, 2020, 2021; Djezzar & Boualam, 2020), with NFs contributing to well productivity. However, intersection of HF with NF may negatively affect the propagation of the HF and the proppant placement, making pressure analysis and prediction of fracture morphology very difficult. Moreover, proppant may accumulate in the near region of the intersection by forming a proppant bridge(Kou et al., 2019), or that it is a continuous transport behavior of proppant in the natural fracture(Kou et al., 2018). Therefore, it is important to anticipate and understand intersection mechanisms when designing and executing HF treatment.