Fracture Network Development and Proppant Placement during Slickwater
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SPE 135484
Fracture Network Development and Proppant Placement during Slickwater
Fracturing Treatment of Barnett Shale Laterals
Wenyue Xu, Marc Thiercelin, Joel Le Calvez, Ruhao Zhao, Utpal Ganguly, Xiaowei Weng, Hongren Gu,
Schlumberger; Jerry Stokes, Mid-Continent Geological Inc.; Horacio Moros, EagleRidge Energy
Copyright 2010, Society of Petroleum Engineers This paper was prepared for presentation at the SPE Annual Technical Conference and Exhibition held in Florence, Italy, 19–22 September 2010. This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of SPE copyright.
Abstract
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 σh and maximum principle stress σH 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 2 SPE 135484
A couple of important approximations were made to simplify the mathematical expression of the model. The first is to assume
an elliptic fluid flow through the HFN from the center to its edge. It is also assumed that at any given point of time a mechanical
equilibrium of the HFN is reached. The latter enables a quasi-steady description of the HFN geometry. The mathematical model
constructed based on the mechanisms mentioned above together with these assumptions can be expressed by a set of three
algebraic equations posed in terms of treatment parameters (pumping duration tp, slurry rate q, fluid viscosity μ, bottomhole net
pressure Δp), formation mechanical properties (Young’s modulus E, Poison’s ratio ν), stress field (minimum principle stress σh,
maximum principle stress σH) and HFN geometry parameters (spacing dx and dy, major axis a, minor axis b and mean height h)
(Figure 2). The equation set can be solved to obtain information of the created HFN (dx, dy, Δσ) using measured stimulated volume
parameters (a, b, h) via microseismic monitoring. This approach is suitable for post-job analysis and was applied to characterize
the HFNs created by hydraulic fracturing stimulation of the three Barnett Shale laterals discussed in this paper. The same set of
