An Analytical Framework for Stress Shadow Analysis During Hydraulic Fracturing – Applied to the Bakken Formation, Saskatchewan, Canada

Abstract

Abstract. This paper presents selected results of a broader research project pertaining to the hydraulic fracturing of oil reservoirs hosted in the siltstones and fine grained sandstones of the Bakken Formation in southeast Saskatchewan, Canada. The Bakken Formation contains significant volumes of hydrocarbon, but large-scale hydraulic fracturing is required to achieve economic production rates. The performance of hydraulic fractures is strongly dependent on fracture attributes such as length and width, which in turn are dependent on in-situ stresses. This paper reviews methods for estimating changes to the in-situ stress field (stress shadow) resulting from mechanical effects (fracture opening), poro-elastic effects, and thermo-elastic effects associated with fluid injection for hydraulic fracturing. The application of this method is illustrated for a multi-stage hydraulic fracturing operation, to predict principal horizontal stress magnitudes and orientations at each stage. A methodology is also presented for using stress shadow models to assess the potential for inducing shear failure on natural fractures. The results obtained in this work suggest that thermo and poro-elastic stresses are negligible for hydraulic fracturing in the Bakken Formation of southeast Saskatchewan, hence a mechanical stress shadow formulation is used for analyzing multistage hydraulic fracture treatments. This formulation (and a simplified version of the formulation) predicts an increase in instantaneous shut-in pressure (ISIP) that is consistent with field observations (i.e., ISIP increasing from roughly 21.6 MPa to values slightly greater than 26 MPa) for a 30-stage fracture treatment. The size of predicted zones of shear failure on natural fractures are comparable with the event clouds observed in microseismic monitoring when assumed values of 115°/65° are used for natural fracture strike/dip; however, more data on natural fracture attributes and more microseismic monitoring data for the area are required before rigorous assessment of the model is possible.

The hydraulic fracturing design technology and application of geological-engineering integration for tight gas in jinqiu gas field

“…This study figure out the main control engineering parameters of different types of reservoirs, and the optimization sequence of stimulation process and fracturing parameters. Affected by fluid filtration (Davletbaev, 2012) and inter fracture interference (Gorjian et al, 2021) during fracture propagation period, the fracture length of Class I reservoir is smaller than that of Class II and III reservoirs under the same fluid strength (Figure 11). The According to the fracture propagation and productivity simulation results (Figures 13,14), the main engineering factor in JQ511 platform fracturing design is cluster spacing.…”

Experimental investigation on the hydraulic fracture initiation and propagation of temporary plugging and acid fracturing in a large-scale true triaxle simulation

“…However, relying solely on a single main fracture during development may not yield the desired increase in production for ultra-low permeability reservoirs. In recent years, petroleum scientists have directed their attention towards fracture network fracturing technology, which leverages newly created fractures as well as reopened secondary fractures to enhance well productivity by increasing discharge volume [6][7][8][9]. This approach enables dynamic control over reserves [10][11][12][13][14].…”

“…Some scholars have developed threedimensional numerical models to simulate fracture initiation under different completion methods based on hypothetical strata. They also consider factors such as completion methods, cluster spacing, in-situ stress, and weak interfaces that in uence fracturing fractures [15][16][17][18][19][20]. Hou et al [21,22] investigated the behavior of hydraulic fracture propagation in a 30 cm shale outcrop cube with natural fractures and examined the impact of geological and engineering factors on it.…”