scholarly journals Propellant Stimulation and Hydraulic Fracturing

2021 ◽  
Vol 9 (6) ◽  
pp. 80-96
Author(s):  
Essa Georges Lwisa
Keyword(s):  
Hydraulic Fracturing ◽  
Compressive Stress ◽  
Fluid Flows ◽  
Injection Rate ◽  
Explosive Material ◽  
Material Quality ◽  
Reservoir Rocks ◽  
A Value ◽  
Principal Elements

The Propellant Stimulation is applied to increase the permeability of rocks; a certain quantity of explosive material is donated at the bottom of the well opposite the producing layer, which causes many cracks in the near well area. A good Propellant Stimulation process must consider the explosive material quality and quantity, and the explosion should be prevented from vertically spread so all its energy will be used to crack the rocks. The first part of this chapter explains all the above in addition to the directed explosions and its calculation in an easy way. In the second part, I explained the Hydraulic Fracturing of the reservoir rocks in details, from principal elements of the process passing through cracking fluids, proppants, preparing the wells and ending with evaluating the effectiveness and discussing the methods of hydraulic fracturing. Hydraulic fracturing is the process of pumping fluid into a wellbore at an injection rate that is too high for the formation to accept without breaking. During injection the resistance to flow in the formation increases, the pressure in the wellbore increases to a value called the break-down pressure, that is the sum of the in-situ compressive stress and the strength of the formation. Once the formation “breaks down,” a fracture is formed, and the injected fluid flows through it.

DEM modeling of hydraulic fracturing in permeable rock: influence of viscosity, injection rate and in situ states

2018 ◽  
Vol 13 (5) ◽  
pp. 1187-1202 ◽  
Author(s):  
Kang Duan ◽  
Chung Yee Kwok ◽  
Wei Wu ◽  
Lu Jing
Keyword(s):  
Hydraulic Fracturing ◽  
Injection Rate ◽  
Permeable Rock

Field Experiments on Hydraulic Fracturing

1972 ◽  
Vol 12 (01) ◽  
pp. 69-77 ◽  
Author(s):  
Hilmar von Schonfeldt ◽  
C. Fairhurst
Keyword(s):  
Hydraulic Fracturing ◽  
Pore Pressure ◽  
Compressive Stress ◽  
Rupture Strength ◽  
Breakdown Pressure ◽  
Near Surface ◽  
Fracturing Process ◽  
Fluid Penetration ◽  
Regional Stresses

Abstract Hydraulic fracturing experiments at two underground and one near-surface location in igneous and shale formations were described. The tests were designed to study the feasibility of hydraulic fracturing as a method of determining in-situ stresses. The tests were carried out in open holes of 2-3/8-in. diameter. Fracturing tests on two 5-ft diameter cores were also reported. The test results revealed an increase in the magnitude of the stress as the face of an opening was approached from inside a rock mass. Horizontal fractures also were observed in areas of reportedly high lateral stress, providing some evidence for the validity of the providing some evidence for the validity of the principle of least resistance. The results also principle of least resistance. The results also indicate that caution must be used in using the shut-in pressure as a measure of the least compressive stress. Introduction Hydraulic fracturing is best known as a well stimulation method. There are other important applications, however, for which the process shows great potential. One of these is in the area of in-situ stress determination as suggested by Scheidegger Kehle and Fairhurst. The mechanics of the fracturing process is the same in any application, and improvement of the method may therefore be expected through a mutual exchange of experience in each of these areas. The theory of the hydraulic fracturing technique relates measurable quantities such as the breakdown pressure and the instantaneous shut-in pressure to pressure and the instantaneous shut-in pressure to the tectonic stresses and certain physical rock properties. properties. Assuming negligible pore pressure and fluid penetration, the break-down pressure (pC) at the penetration, the break-down pressure (pC) at the instant of fracture initiation is given by the following expressions....................(1) when the fracture extends in a "radial" direction (in a plane parallel to the axis of the borehole). And...................(2) when the fracture extends in a direction normal to the borehole axis. Corresponding expressions that include the effect of pore pressure and fluid penetration are given in the literature Because our work was done in dry and impermeable formations, Eqs. 1 and 2 are considered adequate. These formulae are based on the assumption that the borehole is drilled parallel to 3 and that the rock behaves as a linearly elastic isotropic material; it also assumes that the fracture is initiated in a direction perpendicular to the least compressive stress, i.e., 2 or 3, respectively, in accordance with the principle of least resistance. The terms "radial" and "normal" fractures are introduced in place of the commonly used terms "vertical" and "horizontal" fractures in order to avoid possible confusion in the event a borehole is drilled in a direction other than the vertical. Eqs. 1 and 2 establish a simple relation between the breakdown pressure and the regional (far-field) stresses. It also has been suggested that the instantaneous shut-in pressure is a measure for the least compressive stress because a fracture will propagate in a direction normal to it. Therefore, propagate in a direction normal to it. Therefore, or ..........................(3) Thus Eqs. 1 and 3 may serve to estimate the regional stresses 1, and 2 provided it is known that a radial fracture was generated, and it is possible to determine the rupture strength (K ). possible to determine the rupture strength (K ). Similarly Eqs. 2 or 3 will give an estimate of the stress 3. Scheidegger and Kehle determined regional stresses through a similar analysis of hydraulic fracturing data. SPEJ P. 69

scholarly journals Study on Propagation Behaviors of Hydraulic Fracture Network in Tight Sandstone Formation with Closed Cemented Natural Fractures

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-22
Author(s):  
Jun Zhang ◽  
Yu-Wei Li ◽  
Wei Li ◽  
Zi-Jie Chen ◽  
Yuan Zhao ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Fracture Network ◽  
In Situ Stress ◽  
Injection Rate ◽  
Fluid Viscosity ◽  
Tight Sandstone ◽  
Propagation Behavior ◽  
Sandstone Formation

Natural fractures in tight sandstone formation play a significant role in fracture network generation during hydraulic fracturing. This work presents an experimental model of tight sandstone with closed cemented preexisting fractures. The influence of closed cemented fractures’ (CCF) directions on the propagation behavior of hydraulic fracture (HF) is studied based on the hydraulic fracturing experiment. A field-scaled numerical model used to simulate the propagation of HF is established based on the flow-stress-damage (FSD) coupled method. This model contains the discrete fracture network (DFN) generated by the Monte-Carlo method and is used to investigate the effects of CCFs’ distribution, CCFs’ strength, and in-situ stress anisotropy, injection rate, and fluid viscosity on the propagation behavior of fracture network. The results show that the distribution direction of CCFs is critical for the formation of complex HFs. When the angle between the horizontal maximum principal stress direction and the CCFs is in the range of 30° to 60°, the HF network is the most complex. There are many kinds of compound fracture propagation patterns, such as crossing, branching, and deflection. The increase of CCFs’ strength is not conducive to the generation of branched and deflected fractures. When the in-situ stress difference ranges from 3 MPa to 6 MPa, the HF network’s complexity and propagation range can be guaranteed simultaneously. The increase in the injection rate will promote the formation of the complex HF network. The proper increase of fracturing fluid viscosity can promote HF’s propagation. However, when the viscosity is too high, the complex HFs only appear around the wellbore. The research results can provide new insights for the hydraulic fracturing optimization design of naturally fractured tight sandstone formation.

scholarly journals Investigation of Hydraulic Fracturing Behavior in Heterogeneous Laminated Rock Using a Micromechanics-Based Numerical Approach

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3500
Author(s):  
Zhao ◽  
Tannant ◽  
Ma ◽  
Guo ◽  
Feng
Keyword(s):  
Hydraulic Fracturing ◽  
Shear Failure ◽  
Damage Zone ◽  
Numerical Approach ◽  
Injection Rate ◽  
Gas Production ◽  
Tensile Failure ◽  
Rock Matrix ◽  
Stress Ratios

Understanding hydraulic fracturing mechanisms in heterogeneous laminated rocks is important for designing and optimizing well production, as well as for predicting shale gas production. In this study, a micromechanics-based numerical approach was used to understand the physical processes and underlying mechanisms of fracking for different strata orientations, in-situ stresses, rock strengths, and injection parameters. The numerical experiments revealed a very strong influence of the pre-existing weakness planes on fracking. Geological models for rock without weakness planes and laminated rock behave very differently. Most simulated fractures in the rock without weakness planes were caused by tensile failure of the rock matrix. In an intact rock model, although a radial damage zone was generated around the injection hole, most of the small cracks were isolated, resulting in poor connectivity of the fracture network. For rock models with pre-existing weakness planes, tension and shear failure of these structural planes formed an oval-shaped network. The network was symmetrically developed around the injection well because the strength of the pre-existing weakness planes is generally lower than the rock matrix. The research shows that the angular relations between the orientation of the structural planes and the maximum horizontal stress, as well as the in-situ stress ratios, have significant effects on the morphology and extent of the networks. The strength of the pre-existing weakness planes, their spacing, and the injection rate can dramatically influence the effectiveness of hydraulic fracturing treatments.

Simulation of proppant transport and fracture plugging in the framework of a radial hydraulic fracturing model

2020 ◽  
Vol 35 (6) ◽  
pp. 325-339
Author(s):  
Vasily N. Lapin ◽  
Denis V. Esipov
Keyword(s):  
Numerical Model ◽  
Hydraulic Fracturing ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Injection Rate ◽  
Fluid Injection ◽  
Subtraction Technique ◽  
Gas Industry ◽  
Proppant Transport ◽  
Hydraulic Fracture Propagation

AbstractHydraulic fracturing technology is widely used in the oil and gas industry. A part of the technology consists in injecting a mixture of proppant and fluid into the fracture. Proppant significantly increases the viscosity of the injected mixture and can cause plugging of the fracture. In this paper we propose a numerical model of hydraulic fracture propagation within the framework of the radial geometry taking into account the proppant transport and possible plugging. The finite difference method and the singularity subtraction technique near the fracture tip are used in the numerical model. Based on the simulation results it was found that depending on the parameters of the rock, fluid, and fluid injection rate, the plugging can be caused by two reasons. A parameter was introduced to separate these two cases. If this parameter is large enough, then the plugging occurs due to reaching the maximum possible concentration of proppant far from the fracture tip. If its value is small, then the plugging is caused by the proppant reaching a narrow part of the fracture near its tip. The numerical experiments give an estimate of the radius of the filled with proppant part of the fracture for various injection rates and leakages into the rock.

A Value Focused Thinking Approach to Decommissioning Decision Making

2021 ◽  
Author(s):  
Aaron Tung
Keyword(s):  
Decision Making ◽  
Scientific Evidence ◽  
Analysis Tool ◽  
Stakeholder Values ◽  
A Value ◽  
Value Focused Thinking ◽  
Science Theory ◽  
Past Experiences ◽  
Stakeholder Acceptance

Abstract Values are what stakeholders regard to be important to decisions (Kruglanski & Higgins 2007). How stakeholder prioritize, rank, balance, and trade-off values can have significant influence on their reasoning and evaluation of decommissioning outcomes and decisions. Stakeholder values can vary depending on various factors including religious beliefs, personal interests, and past experiences (Lechner et al., 2017). Value-focused thinking is a decision science theory developed by Keeney (1992) which builds upon the concept of varying stakeholder values. Keeney (1992) argues that the best decision is one that best reflects the actual values of stakeholders. which suggests that the acceptability of decommissioning decisions (full removal, partial removal, leave in-situ, rigs-to-reefs, etc.) by stakeholders will vary depending on the values of stakeholder in that particular context. This paper explores the idea of value-focused thinking and derive implications for decommissioning decision-making. Overall, the research finding suggests that rather than basing a decommissioning decision solely on scientific evidence, there is also a need for the decommissioning decisions to be able to reflect the actual values of stakeholders in that particular context. The criteria and weightage of the adopted multi-criteria decision analysis tool, for example, should accurately represent the actual values of stakeholders, so as to enable the tool to produce outcomes and decisions that has a higher probability of stakeholder acceptance.

scholarly journals Elaboration of nitride thin films by reactive sputtering

2006 ◽  
Vol 59 (2) ◽  
pp. 225-232 ◽  
Author(s):  
Pierre Yves Jouan ◽  
Arnaud Tricoteaux ◽  
Nicolas Horny
Keyword(s):  
Thin Films ◽  
Compressive Stress ◽  
Bias Voltage ◽  
Substrate Surface ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
A Value ◽  
Dc Reactive Magnetron Sputtering ◽  
Nitrogen Contents

The aim of this paper is first a better understanding of DC reactive magnetron sputtering and its implications, such as the hysteresis effect and the process instability. In a second part, this article is devoted to an example of specific application: Aluminium Nitride. AlN thin films have been deposited by reactive triode sputtering. We have studied the effect of the nitrogen contents in the discharge and the RF bias voltage on the growth of AlN films on Si(100) deposited by triode sputtering. Stoichiometry and crystal orientation of AlN films have been characterized by means of Fourier-transform infrared spectroscopy, X-ray diffraction and secondary electron microscopy. Dense and transparent AlN layers were obtained at high deposition rates. These films have a (002) orientation whatever the nitrogen content in the discharge, but the best crystallised ones are obtained at low value (10%). A linear relationship was observed between the AlN lattice parameter "c" (perpendicular to the substrate surface) and the in-plane compressive stress. Applying an RF bias to the substrate leads to a (100) texture, and films become amorphous. Moreover, the film's compressive stress increases up to a value of 8GPa before decreasing slowly as the bias voltage increases.

scholarly journals Protein kinase C and calcineurin cooperatively mediate cell survival under compressive mechanical stress

2017 ◽  
Vol 114 (51) ◽  
pp. 13471-13476 ◽  
Author(s):  
Ranjan Mishra ◽  
Frank van Drogen ◽  
Reinhard Dechant ◽  
Soojung Oh ◽  
Noo Li Jeon ◽  
...  
Keyword(s):  
Cell Survival ◽  
Mechanical Stress ◽  
Compressive Stress ◽  
Surface Protein ◽  
Downstream Signaling ◽  
Cell Responses ◽  
Single Cell Responses ◽  
Map Kinase Pathway ◽  
Mediate Cell

Cells experience compressive stress while growing in limited space or migrating through narrow constrictions. To survive such stress, cells reprogram their intracellular organization to acquire appropriate mechanical properties. However, the mechanosensors and downstream signaling networks mediating these changes remain largely unknown. Here, we have established a microfluidic platform to specifically trigger compressive stress, and to quantitatively monitor single-cell responses of budding yeast in situ. We found that yeast senses compressive stress via the cell surface protein Mid2 and the calcium channel proteins Mid1 and Cch1, which then activate the Pkc1/Mpk1 MAP kinase pathway and calcium signaling, respectively. Genetic analysis revealed that these pathways work in parallel to mediate cell survival. Mid2 contains a short intracellular tail and a serine−threonine-rich extracellular domain with spring-like properties, and both domains are required for mechanosignaling. Mid2-dependent spatial activation of the Pkc1/Mpk1 pathway depolarizes the actin cytoskeleton in budding or shmooing cells, thereby antagonizing polarized growth to protect cells under compressive stress conditions. Together, these results identify a conserved signaling network responding to compressive mechanical stress, which, in higher eukaryotes, may ensure cell survival in confined environments.

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