Effect of Dynamic Active Fracture Interaction DAFI on Activation of Natural Fractures in Horizontal Wells

2016 ◽  
Author(s):  
Ali Daneshy
Keyword(s):  
Horizontal Wells ◽  
Natural Fractures ◽  
Active Fracture ◽  
Fracture Interaction

Laboratory study of Hydraulic Fracture interaction with artificial interfaces.

2020 ◽  
Author(s):  
Anna Shevtsova ◽  
Egor Filev ◽  
Maria Bobrova ◽  
Sergey Stanchits ◽  
Vladimir Stukachev
Keyword(s):  
Hydraulic Fracturing ◽  
Laboratory Study ◽  
Deformation Monitoring ◽  
Unconventional Reservoirs ◽  
Fluid Viscosity ◽  
Natural Fractures ◽  
Bedding Planes ◽  
Hf Propagation ◽  
Fracture Interaction ◽  
Series Of Experiments

<p>Nowadays Hydraulic Fracturing (HF) is one of the most effective stimulation technique for hydrocarbon extraction from unconventional reservoirs, as well as enhanced geothermal applications. Practical applications of HF can have different aims. In one case, we need to stop cracks inside the host rock to avoid some HF breakthroughs into other formations and possible groundwater pollutions. The second situation is when we need to fracture several bedding planes in a reservoir which has a complex structure, especially in case of the presence of multiple natural fractures in unconventional reservoir. It is important to study hydraulic fracturing, its propagation and conditions of interaction with interfaces in laboratory conditions before expensive field application.</p><p>The present work demonstrates the results of a laboratory study designed to understand fracture interaction with artificial interfaces. For the first series of experiments, we used some natural materials such as shales, sandstones, dolomites and limestones with different porosity, permeability and mechanical properties. During these experiments we initiated hydraulic fracturing in homogeneous specimens with and without artificial surfaces, modelling natural fractures or bedding planes in unconventional reservoirs. For the second series of experiments, we used a combination of different materials to understand HF propagation in heterogeneous media, to study conditions of HF crossing or arrest at the boundaries between different types of rock. These laboratory experiments were done to create HF simulating natural processes in fractured and heterogeneous rocks or reservoirs.</p><p>Series of hydraulic fracturing experiments under uniaxial load conditions were conducted using the multifunctional system MTS 815.04. Before testing, samples were scanned by 3D CT System to characterize the rock fabric, and after testing, CT scanning was repeated to characterize 3D shape of created HF. The dynamics of HF initiation and propagation was monitored by Acoustic Emission (AE) technique, using piezoelectric sensors glued to the surface of the rock to record elastic waves radiated during the process of HF propagation. The experiments were made with different injection rates and fluid viscosities. Changes in radial strain, injection pressure and microseismic data over time were recorded.</p><p>As the result, these experiments indicate significant factors (rock heterogeneity, porosity, permeability, fluid viscosity and injection rate), influencing cracks initiation, propagation or arrest on the artificial interface. The fracture propagation and opening are characterized by measured radial deformation, fluid pressure and geometrical orientation in the sample volume. The experiments demonstrated, that fracture easily crossed artificial surface in the homogeneous limestone samples. And cracks initiated in limestone were arrested on the border with shale. In all cases combination of the AE and deformation monitoring allows to indicate fracture initiation, propagation and arrest.</p>

Seismic azimuthal anisotropy analysis after hydraulic fracturing

2013 ◽  
Vol 1 (2) ◽  
pp. SB27-SB36 ◽  
Author(s):  
Kui Zhang ◽  
Yanxia Guo ◽  
Bo Zhang ◽  
Amanda M. Trumbo ◽  
Kurt J. Marfurt
Keyword(s):  
Hydraulic Fracturing ◽  
Anisotropy Field ◽  
Horizontal Wells ◽  
Horizontal Stress ◽  
Azimuthal Anisotropy ◽  
Barnett Shale ◽  
Natural Fractures ◽  
Tight Sandstone ◽  
Induced Fractures ◽  
Maximum Horizontal Stress

Many tight sandstone, limestone, and shale reservoirs require hydraulic fracturing to provide pathways that allow hydrocarbons to reach the well bore. Most of these tight reservoirs are now produced using multiple stages of fracturing through horizontal wells drilled perpendicular to the present-day azimuth of maximum horizontal stress. In a homogeneous media, the induced fractures are thought to propagate perpendicularly to the well, parallel to the azimuth of maximum horizontal stress, thereby efficiently fracturing the rock and draining the reservoir. We evaluated what may be the first anisotropic analysis of a Barnett shale-gas reservoir after extensive hydraulic fracturing and focus on mapping the orientation and intensity of induced fractures and any preexisting factures, with the objective being the identification of reservoir compartmentalization and bypassed pay. The Barnett Shale we studied has near-zero permeability and few if any open natural fractures. We therefore hypothesized that anisotropy is therefore due to the regional northeast–southwest maximum horizontal stress and subsequent hydraulic fracturing. We found the anisotropy to be highly compartmentalized, with the compartment edges being defined by ridges and domes delineated by the most positive principal curvature [Formula: see text]. Microseismic work by others in the same survey indicates that these ridges contain healed natural fractures that form fracture barriers. Mapping such heterogeneous anisotropy field could be critical in planning the location and direction of any future horizontal wells to restimulate the reservoir as production drops.

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