Utpal Ganguly

Fracture Network Development and Proppant Placement During Slickwater Fracturing Treatment of Barnett Shale Laterals

This paper presents an application of the wiremesh hydraulic fracturing model to analyze slickwater fracturing stimulation treatments of three Barnett Shale horizontal gas wells. For each treatment stage, the created hydraulic fracture network (HFN) was characterized on the basis of associated microseismic events distribution, treatment data, and geomechanical properties of involved formation layers. A systematic analysis of all stages, such as the potential effect of earlier treatment stages on a later one, the relationship between HFN properties such as the fracture surface area and treatment parameters, etc, was also presented. The information obtained was then applied to examine proppant placement in each of the HFNs. Potential ways of treatment improvement and optimization for future jobs are discussed based on these analyses. Introduction Slickwater fracturing stimulation has been applied to many shale gas plays to enhance gas production. However better understanding of how the induced HFN grows and where proppants are placed is still needed more than ever. A new model (Xu et al. 2009a, Xu et al. 2009b, Xu et al. 2010) was developed to represent a HFN on average by an increasing stimulated shale volume consisting of two perpendicular sets of vertical planar fractures in a vertically variable and horizontal anisotropic stress field quantified by the horizontal minimum principle stress h and maximum principle stress H for each of involved formation layers (Figure 1). The size of the stimulated formation is described by the major axis a, the minor axis b and the mean height h of an expanding ellipsoid. The HFN is further characterized by its fracture spacing parameters dx and dy. Mechanical interactions among fractures and between injected fluid and fracture walls are accounted for. HFN growth is constrained by the amount and rate of fluid injection. Figure 1. Wiremesh model of complexe hydraulic fracture network illustrating (a) the expanding stimulated formation volume containing (b) the hydraulic fracture network

Multidomain Data and Modeling Unlock Unconventional Reservoir Challenges

32 JPT • AUGUST 2012 Completion strategy and hydraulic fracture stimulation are important keys to economic success in lowpermeability and unconventional reservoirs such as tight sand and shale. Therefore, engineering workflows in unconventional reservoirs need to focus on completion and stimulation optimization, just as they do well placement and spacing. The primary obstacles associated with optimizing completions in these reservoirs have been the absence of hydraulic fracture models that properly simulate the complex fracture propagation common in many reservoirs, the lack of efficient methods to create discrete reservoir simulation grids to rigorously model hydrocarbon production from complex hydraulic fractures, the lack of automated fracture treatment staging algorithms, and the lack of ability to efficiently integrate microseismic mapping measurements with geological and geophysical data. This article details a novel approach for enabling efficient multistage completions, new complex fracture models, unstructured gridding-based reservoir simulation, and a comprehensive integrated workflow developed within single reservoir-centric stimulation design software. Though primarily focused on unconventional reservoirs, this efficient full-cycle seismic-tosimulation workflow is applicable also for conventional reservoirs.