ABSTRACT:

Multi-stage hydraulic fracturing technology for enhanced production from unconventional reservoirs has improved significantly during the past decade. However, multi-stage fracturing for multiple closely spaced long horizontal wellbores introduces several technical challenges. One example is Fracture Driven Interaction (FDI). In this study, we document a Fracture Driven Interaction case study where the primary well was drilled into the Three Forks Formation, and an offset well was drilled in the Middle Bakken. The idea of this study was to investigate the possibility of frac-hit as the cause of low production rate in the offset well. This study estimates the stress in the petroleum system, and combine that with petrophysical analysis to construct a fully coupled hydraulic fracturing, geomechanics and reservoir numerical model. The model matched the production data and the results show the occurrence of a fracture driven interaction was a result of stress decrease due to depletion. Fracture driven interaction effect was severe on the offset well reducing the stimulated reservoir volume, thus jeopardizing the production.

1. INTRODUCTION

During the last decade, hydraulic fracturing designs included larger proppant volume injection in order to maximize stimulated reservoir volume (SRV) and increase recovery (Gupta et al., 2021; Seth et al., 2020; Xu et al., 2018). Along with implementing multi-pads, a connection between fractures from adjacent wells was noted. This connection was defined as Fracture Driven Interaction (FDI) so called frac-hit or frac-bashing (Daneshy, 2020). Miller et al. (2016) reported the impact of FDI on production for several plays of the United States. This effect can cause either an increase or a decrease in production. FDI was first reported in the work of Ajani and Kelkar (2012). Gupta et al. (2021) reported the factors that can cause an FDI to occur. In this work, we focus on two factors: stress profile and depletion.

When depleting the primary well (parent well), pore pressure decreases, leading to a decrease in the total stress around the primary well. Consequently, the new distribution of stress will cause asymmetric growth in the fractures of the offset well (child well). The asymmetric growth reduces the stimulated reservoir volume because the fractures grow in the direction of the depleted zones, i.e., the zones with the least resistance to propagation (Ajani & Kelkar, 2012; Daneshy & King, 2019; Gupta et al., 2021; Kumar et al., 2020; Manchanda et al., 2017; Rezaei et al., 2019; Seth et al., 2020; Zheng et al., 2019)

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