Laboratory Experiments Contrasting Growth of Uniformly and Nonuniformly Spaced Hydraulic Fractures

Abstract

Because of major advances in hydraulic fracturing and horizontal drilling technology, vast tracts of gas bearing shale formations have become a significant source of hydrocarbon production in North America and beyond. These formations are called unconventional resources because they cannot be developed and produced by conventional production methods. As a result of their low permeability, higher intensity operations such as drilling a horizontal wellbore in the formation and creating multiple transverse hydraulic fractures crossing this wellbore are essential to make unconventional reservoirs economically viable. Although the type of formation and experience with horizontal wells in a specific formation will dictate the most appropriate type of well completion to be used, a commonality is the use of simultaneous injection into multiple entry points (i.e., clusters of perforation holes made in the casing and cement) with the intent of creating multiple hydraulic fractures in each of multiple, repeated stages (see Figure 1). Typically, each stage comprises three to six perforation clusters, and each stage is repeated 20-40 times on each well. The goal of this completion technique is to generate uniform hydraulic fractures from all perforation clusters within a stage; hence, to create high conductivity pathways to the formation for oil and gas production that uniformly stimulate the reservoir rock. However, industry experience with field data analysis (i.e., production logging during which a flow sensor is moved through the well to measure the contribution of each perforation cluster to the overall production rate) and predictions from simulations make it clear that uniform stimulation can be an elusive goal. For example, Miller et al. (2011) interpreted hundreds of production logs from multiple basins, concluding that approximately two thirds of perforation clusters contribute to well production. Similarly, Molenaar et al. (2012) published one of the first studies using distributed acoustic sensing (DAS) technology with fiber optic cables in a horizontal wellbore, thereby detecting that

Physics-embedded inverse analysis with algorithmic differentiation for the earth’s subsurface

“…At the same time, for almost all depths of interest, the hydraulic fracture will be normal to the direction of the horizontal well. In this study, a cluster with five hydraulic fractures has been selected to present the process of inverse analysis during gas production 60 . A medium-scale matrix of size 100 m × 100 m, with a 78 m drilled well in the center position, was used to represent the research domain.…”

Perforation Optimization of Intensive-Stage Fracturing in a Horizontal Well Using a Coupled 3D-DDM Fracture Model

“…A hydraulic fracture is treated as a discontinuous displacement plane. The displacement discontinuity method (DDM) provides the displacement and stress solutions in an infinite elastic medium [12,37]. The 3D DDM is based on the elastic solution to the problem of a discontinuous displacement over a finite area in an infinite region [38].…”

“…Extensive numerical methods were developed to model the fracture propagation, such as the extended finite element method [9][10][11], boundary element method [12][13][14], discrete element method [15,16], phase field method [17], peridynamics [18,19] and cracking particles [20], etc. Usually, in hydraulic fracture simulators, the rock is assumed to be an isotropic linear elastic medium, and thus the boundary element method constitutes an efficient method because only the boundary is discretized, and it yields accurate results for linear elastic fracture mechanics.…”

Multiscale Spatial Patterns in Giant Dike Swarms Identified Through Objective Feature Extraction

“…These studies have highlighted the critical role of crustal layering (both rigidity and density layering), topographic stresses, magma buoyancy, and magma inflow rate in controlling the spatial pattern of dike propagation (e.g., vertical vs. lateral propagation) (Kavanagh et al., 2015; Urbani et al., 2018). Despite uncertainties about how well single dike models extrapolate to large dike swarms with complex inter‐dike interaction (Gunaydin et al., 2021), dike swarms have been widely interpreted in terms of paleostresses and as direct evidence of a transcrustal magma plumbing system (Mittal et al., 2021; Rivalta et al., 2015).…”