A Simulation Approach to Modelling and Understanding Fracture Geometry with Respect to Well Spacing in Multi Well Pads in the Duvernay – A Case Study

Abstract

Hydraulic fracturing in multi stage horizontal unconventional wells is perhaps one of the most important if not the most important in the drilling and completion cycle of these wells. It's also the most applied technique repeatedly in multiple formations throughout the world and yet the question that looms large over us, do we understand the fracture geometry in these unconventional environments.Year on year most unconventional formations seem to fall in line with the industry trend of increasing lateral lengths and pumping more stages to improve production and recovery. Again, we need to ask ourselves if this is sustainable. Introspection of data available from public data seems to indicate that a significant chunk of these wells buck the trend of increased lateral lengths and stages and we still continue to apply these techniques especially in a price sensitive oil market. What if we could challenge this paradigm through a systematic engineering process that could relate the impact of fracture geometry and well spacing? We selected one of the up and coming plays in Canada that is on the road to development called the Duvernay.The Duvernay Formation is a unit of the Woodbend Group and is considered as the source rock for prolific reservoirs such as the Leduc reefs. Duvernay formation holds an estimated 443 trillion cubic feet of gas and 61.7 billion barrels of oil.This paper is an attempt to model and understand complex hydraulic fractures in a multi well pad environment coupled with production modelling to understand drainage patterns. Public data from the IHS database was used to construct and build a geocellular model and wells that had petrophysical and geomechanical data were used to build a representative well pad model. Using the model built complex fractures using the unconventional fracture models were simulated in a multi well pad environment. Impact on reservoir drainage has been assessed with various simulations by changing different parameters with respect to hydraulic fracturing. The results of these various simulations are presented in the paper and these simulations act as a tool to understand when possible interference may occur in these pads. Spacing of wells and frac sizes can be adjusted to minimize competitive drainage between wells.

Interaction of natural and hydraulic fractures: the impact on reservoir pressure buildup and risk of shear fault reactivation in the Upper Devonian Duvernay Formation, Fox Creek, Alberta

“…The HFM results presented in this study (Fig. 6, 9) are similar to complex hydraulic fracture networks simulated in the Duvernay Formation and reported earlier (Ramanathan et al 2015;Ferrer et al 2020). Based on the results of HF simulations with DFN-1 (Case 1) and DFN-2 (Cases 2 and 3) of this study (Fig.…”

“…Numerical simulations studies have shown that presence of natural fractures in a formation impacts hydraulic fracture propagation resulting in complex HFs-NFs networks (Weng et al 2011;Wu et al 2012;Haege et al 2015;Weng 2015;Rutqvist et al 2018). The fracture network complexity contributes to the efficiency of hydraulic fracturing operations in unconventional reservoirs (Ramanathan et al 2015;Ferrer et al 2020;Li et al 2020). Additionally, fluid pressure transmission through complex HFs-NFs networks in tight fractured formations may result in shear slip reactivation of critically-stressed faults and induced seismicity.…”

A Novel Optimization Workflow Coupling Statistics-Based Methods to Determine Optimal Well Spacing and Economics in Shale Gas Reservoir with Complex Natural Fractures

“…Alternative approaches include the consideration of geomechanics [11] and microseismic analysis [12], but these face the issues of inadequate data, due to high data acquirement costs and extra uncertainty, which is especially observed in the noisy microseismic data. Extensive analytical and numerical simulation approaches have been conducted for the well spacing problem by various authors [13][14][15], since it is relatively cheap. However, these simulations rarely consider the subsurface uncertainties associated with the fractures.…”