Top PDF Creation and Impairment of Hydraulic Fracture Conductivity in Shale Formations

Creation and Impairment of Hydraulic Fracture Conductivity in Shale Formations

Creation and Impairment of Hydraulic Fracture Conductivity in Shale Formations

The modified ISO test, or non-ISO standard test, on the other hand, has been made by various research parties for different applications. Among these, the commonest modification is to use a modified API conductivity cell to accommodate 3 times thicker samples to account for fluid leakoff through the sample during the experiment. Instead of flowing 2% KCl through the fracture as specified by ISO standards, the modified tests can flow dry gas, wet gas, fresh water, brine of various concentrations and multi-phase flow for different reasons, such as protecting the shale sample by flowing dry nitrogen (Zhang et al. 2013a), keeping the gel hydrated by wet gas (Awoleke et al. 2012), studying the water sensitivity (Conway et al. 2011), and investigating the effect of multiphase flow and non-Darcy flow (Barree et al. 2009). Both cylindrical core plugs and samples of API dimensions (7 inch long, 1.5 inch wide with curved ends) are used in the non-ISO tests (Ramurthy et al. 2011). Moreover, proppants are placed on smooth saw-cut Berea sandstone samples in ISO tests while any type of rock with either saw-cut smooth faces or rough faces can be used in the non-ISO tests.
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A Comprehensive Study of the Eagle Ford Shale Fracture Conductivity

A Comprehensive Study of the Eagle Ford Shale Fracture Conductivity

Hydraulic fracturing is a stimulation process that involves pumping a pressurized mixture of fluids, chemicals and proppants (usually sand) down a well. On high permeability reservoirs the objective of hydraulic fracturing is to bypass a damage zone near the wellbore. On the other hand, in low permeability formations like shale reservoirs the objective is to increase the contact area with the reservoir so commercial flow rates can be obtained. The hydraulic fracturing process begins with pumping pad fluid at pressures higher than the formation fracturing pressure which fractures the rock. Next, proppants are added to the fluids and it is expected that the proppants will fill the newly created fractures and keep them open once the pumping stage is over. Chemicals are added at every stage of the hydraulic fracturing process. These chemicals are used to reduce the friction between the slurry and the pipe, increase and maintain the fluid viscosity, limit corrosion and scale deposition in the pipe, clean the perforations and to avoid/minimize formation damage.
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The Effects of Fracture Orientation and Anisotropy on Hydraulic Fracture Conductivity in the Marcellus Shale

The Effects of Fracture Orientation and Anisotropy on Hydraulic Fracture Conductivity in the Marcellus Shale

To approximate horizontal fractures, samples were broken parallel to the bedding planes. Although the bedding planes may have a non-zero dip angle at formation depths, the dip angle is assumed to be low enough to make this a valid approximation. That said, fractures in formations such as the Marcellus do not usually propagate horizontally because of the large overburden pressure at depth. However, the current literature on the subject of propped fracture conductivity has used horizontally-fractured samples for discussion. Operators who test fracture conductivity also generate samples with this fracture orientation, meaning that horizontally-fractured samples remain the best way to compare results from this work to those from previous studies or operator data.
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Predicting Hydraulic Fracture Conductivity In Shale Plays

Predicting Hydraulic Fracture Conductivity In Shale Plays

Even though mechanical properties were varied in the shale conductivity experiments, many other variables were present which made it difficult to pinpoint the effects each property was having on conductivity. In addition, there were significant gaps in the data where important mechanical properties were not measured for certain formations. For example, Brinell hardness was only measured for the Eagle Ford dataset and compressive strength only for the Marcellus samples. This section presents results from a new rock mechanics study, which isolated the properties of Brinell hardness, Young’s Modulus, Poisson’s ratio, and compressive strength. The relationship between these parameters and fracture conductivity is discussed along with validation for how these properties should be handled in the conductivity correlations. The four formations investigated were Austin chalk, Lueders limestone, Crab Orchard sandstone, and Castlegate sandstone. These rocks were readily available and offered a wide range of mechanical properties, which were the primary concerns in sample selection.
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The Effect of Proppant Size and Concentration on Hydraulic Fracture Conductivity in Shale Reservoirs

The Effect of Proppant Size and Concentration on Hydraulic Fracture Conductivity in Shale Reservoirs

Hydraulic fracture conductivity in ultra-low permeability shale reservoirs is directly related to well productivity. The main goal of hydraulic fracturing in shale formations is to create a network of conductive pathways in the rock which increase the surface area of the formation that is connected to the wellbore. These highly conductive fractures significantly increase the production rates of petroleum fluids. During the process of hydraulic fracturing proppant is pumped and distributed in the fractures to keep them open after closure. Economic considerations have driven the industry to find ways to determine the optimal type, size and concentration of proppant that would enhance fracture conductivity and improve well performance. Therefore, direct laboratory conductivity measurements using real shale samples under realistic experimental conditions are needed for reliable hydraulic fracturing design optimization.
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The Effect of Rock Properties on Hydraulic Fracture Conductivity in the Eagle Ford and Fayetteville Shales

The Effect of Rock Properties on Hydraulic Fracture Conductivity in the Eagle Ford and Fayetteville Shales

In order to characterize the mechanical properties of the shale formations, a triaxial rock testing system was used. The GCTS RTX-1500 Triaxial Rock Testing System is specifically designed to test rock parameters such as Young’s Modulus and Poisson’s Ratio while controlling confining and pore pressures. The system is capable of measuring the properties of rock samples with diameters up to 2 inches and sample lengths up to 4 inches. An axial load of up to 1500 kN can be applied to the rock. The system is capable of confining pressures of up to 20,000 psi. It is also capable of maintaining an internal rock pore pressure of up to 20,000 psi. For the purposes of this research, the full loading capabilities (axial, confining, and pore) were unnecessary. The pore pressure capabilities were not used at all. The major benefit of the GCTS RTX- 1500 system is the deformation instrumentation and data acquisition. Internal instrumentation, using Linear Variable Differential Transformers (LVDTs), is able to measure axial and circumferential deformations as small as 0.001 millimeters. The RTX- 1500 meets the specifications of the International Society of Rock Mechanics (ISRM) for rock sample triaxial tests.
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Fracture Conductivity Behavior in Shale Formations

Fracture Conductivity Behavior in Shale Formations

The way rock fails enabling the creation of a fracture depends on the stress distribution downhole in the field, and also on the mineralogy distribution of the formation. For whatever the reasons, the fractures created by hydraulic power in the field all have certain degree of unevenness along the fracture face. To understand fracture conductivity behavior, using artificially fractured samples represent an improvement to better emulate the fracture surfaces in the field. For an uneven surface, proppant concentration varied along the fracture surface. Meanwhile, some areas of the fracture surface carried a higher level of stress than others. This non-uniform stress profile along the fracture surface can occur any time the two fracture surfaces do not come in perfect contact with each other. These two features caused by fractured surface topography, uneven proppant distribution and uneven stress distribution, can both enhance fracture conductivity. Hundreds of fracture conductivity experiments were conducted under different test conditions, including by Enriquez (2016), and as summarized and analyzed by Kainer et al. (2017), and others using the same Modified API Fracture Conductivity Cell utilized in this study. All of them used a rough fractured surface instead of a saw-cut smooth surface. Yet, the self-channeling phenomenon was observed in only in a small portion of the tested samples.
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Factors affecting hydraulic conductivity of asphalt mixture

Factors affecting hydraulic conductivity of asphalt mixture

The main objective of this research is to understand the effect of air void topology on the hydraulic conductivity of asphalt mixture. With this purpose, permeability tests have been conducted on asphalt test samples with a wide range of air void content, ranging from 8.7 to 26%, built by changing aggregate grada- tion and using different compaction levels. We have aimed that these materials are representative of asphalt mixture in practice. Furthermore, CT-scans have been used to assess the structure of air voids, and their topological properties have been related to the hydraulic conductivity of asphalt mixture. Finally, a Weibull model for hydraulic conductivity has been proposed and used to explain the relationship between hydraulic conductivity and air voids in commonly used asphalt road materials.
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Probabilistic study on hydraulic conductivity of concrete at mesoscale

Probabilistic study on hydraulic conductivity of concrete at mesoscale

By taking advantage 15 of some of the available analytical models relating conductivity of composite material to volume 16 fraction of non-conductive particles, a new conceptual model re[r]

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Development of Pedotransfer Functions for Saturated Hydraulic Conductivity

Development of Pedotransfer Functions for Saturated Hydraulic Conductivity

[4] noted that data from existing international soil data bases having measured soil data can be analyzed to enable prediction of hydraulic characteristics from measured soil data. Availability of measured soil hydraulic characte- ristics for a wide range of soils and from a large and reliable international data bases are considered prere- quisite for development of pedotransfer functions. The ISRIC soils database was used to obtain measured data on soil hydraulic characteristics and basic soil properties. It was possible to obtain all the required measured data on 457 soil samples from various parts of the world. The data contained measured moisture retention curves as well as data on texture (Sand%, Clay% and Silt%). The ISRIC dataset [11] was used for this test. This dataset contains Water Retention Curve (WRC) for both topsoil (between 0 and 20 cm depth) and subsoil (between 20 and 100 cm) from many countries in the world. It has 8 levels of measured suction potential (at 0, 0.1, 0.312, 1.0, 1.99, 5.01, 2.5, and 15.8 m) (Figure 1). The lowest suction potential was taken as 0.01 to avoid errors with logarithmic trans- formations. The observed moisture retention curve ob- tained from measured data on moisture retention cha- racteristics was fitted to the van Genuchten moisture retention Equation (11)
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The impact of vegetation on hydraulic conductivity of sandy soil

The impact of vegetation on hydraulic conductivity of sandy soil

It can be stated that soil biota and terrestrial plants can change the physical properties of soils through both the hydrophobic coating of the soil particles and the surface-vented macropores. The unsaturated hydraulic conductivity seems to be strongly influenced by the hydrophobic coating due to different plant coverage, which corresponds to the results of WDPT tests. On the other hand, the surface-vented macropores lead the majority of water from ponding (i.e. under the conditions similar to a heavy rain event), as indicated by high values of the share of flux through the pores with radii longer than approximately 0.5 mm. A further study is proposed to make evidence of these statements and to find the direct quantita- Table 3. The impact of vegetation on hydraulic conductivity of sandy soil at the locality Mláky II near Sekule (southwest Slovakia); The results for n measurements are presented in the form: arithmetic mean ± standard deviation
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An investigation of Hydraulic Conductivity Determination for Anisotropic Soils

An investigation of Hydraulic Conductivity Determination for Anisotropic Soils

One of the important parameters for determining the discharge through the subsurface system in groundwater engineering is hydraulic conductivity coefficient. This parameters the factor of oil skeleton and fluid properties. The horizontal and vertical components of saturated hydraulic conductivity coefficient can be obtained from the laboratory and field testing methods. Those are usually constant and variable head tests. In this research the three-dimensional ellipsoid of hydraulic conductivity coefficients is obtained. Using the hydraulic conductivity ellipsoid it is possible of obtain the permeability of soil in any direction. The above model has the effective application for calculation of one, two and three-dimensional fluid flow in the anisotropic porous media. The accuracy of thehydraulic conductivity obtained by the model can be checked by laboratory tests. The model is applied for the calculation of infiltration from the natural or man-made surface channels, also exfilitration from the subsurface water resources.
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Analysis and interpretation of a hydraulic fracture treatment using offset vertical observation wells and a hydraulic fracture simulator

Analysis and interpretation of a hydraulic fracture treatment using offset vertical observation wells and a hydraulic fracture simulator

Further highlighting the importance of establishing an appropriate hydraulic fracture half-length, companies producing from unconventional formations are continually seeking to streamline drilling and completion processes ( Arguijo et al., 2012) . In general, the basic goal of streamlining is to develop one (or several) stimulation treatments and use the same process on all wells within a given field. The benefit for companies is they can better control costs associated with fracturing a well. Costs are better controlled by focusing on one (or several) treatments as opposed to performing a wide range of treatment schedules. The downside however, is that one (or a few) fracture treatment designs will not necessarily be the most effective for extracting hydrocarbons from a shale field.
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DIELECTRIC AND AC CONDUCTIVITY OF POLYSTYRENE/OIL SHALE COMPOSITES

DIELECTRIC AND AC CONDUCTIVITY OF POLYSTYRENE/OIL SHALE COMPOSITES

in anoxic environments. As the deposits are buried by additional sediment, high temperature and pressure remove water and enable chemical reactions that transform the organic matter into kerogen. These reactions can proceed at greater temperatures to produce oil, but oil shale have not been buried to sufficient depths to allow this further conversion [5].Oil shale typically contains enough hydrocarbons to burn in raw form and can be used directly as a solid fuel. However, producing oil from kerogen requires pyrolysis, an energy intensive process in which the rock is heated to) 450-550 o C( in the absence of oxygen. The industrial procedure used to convert oil shale into useful hydrocarbons is called "retorting''.
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Investigating Effects Of Carbonate Minerals On Shale- Hydraulic Fracturing Fluid Interactions In The Marcellus Shale

Investigating Effects Of Carbonate Minerals On Shale- Hydraulic Fracturing Fluid Interactions In The Marcellus Shale

various pH dependent reactions taking place in the shale reservoir. While numerous studies have investigated the dynamics of how carbonates may affect the shale-HFF system, none have analyzed these reactions under representative high pressure temperature well conditions and keeping all other variables constant (Wang et al., 2015, 2016). A recent study indicates that several other factors such as cation exchange on clay surfaces, adsorption of ions in organic matter, and formation of organo-metallic complex compounds affect mineral dissolution and precipitation reactions between shale and HFF (Pilewski et al., 2019). Therefore, to evaluate the true impact of carbonate content in shale-HFF reactions we need to keep other variable constant. The aim of this study was to isolate the effects of carbonate mineral content on the shale-HFF reactions keeping all the other variables constant, and mimicking the subsurface pressure temperature conditions using high pressure temperature reactors. Developing better
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Carbon dioxide injection and associated hydraulic fracturing of reservoir formations

Carbon dioxide injection and associated hydraulic fracturing of reservoir formations

4 The advent of developments in numerical techniques have prompted more studies (Al-Busaidi et al., 2005, Alqahtani and Miskimins, 2010, Boone and Ingraffea, 1990, Boutt et al., 2007, Boutt et al., 2011, Casas et al., 2006, Dean and Schmidt, 2009, El Shamy and Zeghal, 2005, Hoffman and Chang, 2009, Jansen et al., 2008, Lam and Cleary, 1986, Lujun et al., 2009, Papanastasiou, 1997, Rungamornrat et al., 2005, Shimizu et al., 2009, Shimizu et al., 2011, Warpinski et al., 1982, Yamamoto et al., 1999, Yew and Liu, 1993); these have added flexibility that complement field/laboratory experiments which, on their own, have limited and controlled conditions. Examples of the application of numerical methods include the finite element modelling technique used by Alqahtani and Miskimins (2010) to determine the stress distribution caused by the application of predefined sets of triaxial stresses on layered block systems (in order to simulate laboratory experiments) and the use of finite difference techniques by Hoffman and Chang (2009) to model hydraulically fractured wells and predict productivity. In addition, Dean and Schmidt (2009) illustrated the capability of a multiphase/multi-component modelling technique that couples hydraulic fracturing with other processes such as flow through porous media, heat convection and conduction, solids deposition and poroelastic/ poroplastic deformation.
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Microseismic Fracture Mapping Results in the Woodford Shale

Microseismic Fracture Mapping Results in the Woodford Shale

Network Size, Frac Spacing and Conductivity are Key For Production From Shale Networks. Frac Spacing Size[r]

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Review on Shale gas by using Hydraulic Fracturing in India

Review on Shale gas by using Hydraulic Fracturing in India

India is the fourth largest energy consumer in the world after USA, China and Japan. About 52% of her energy requirement is met by coal, 32% by oil and 6% by natural gas (Sen, 2013). Depletion of fossil fuels (coal, oil and natural gas) and non-discovery of major conventional hydrocarbon resources during the last few decades have prompted us to look for alternate sources of energy for development and sustainable growth of India. The Gas-hydrates, Shale gas and Coal bed methane are considered to be major potential resources of energy for India. The shale gas has stolen the spotlight in recent times after its successful production in USA using the hydraulic fracturing and horizontal drilling (King, 2010).
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A Study on Hydraulic Conductivity of Fine Oil Sand Tailings

A Study on Hydraulic Conductivity of Fine Oil Sand Tailings

Miller (2010) carried out a comprehensive study to evaluate the properties and processes influencing the rate and magnitude of volume decrease for fine oil sand tailings resulting from different bitumen extraction processes (caustic versus non- caustic). In this study, the fine content of tailings samples ranged from 96% to 100%. The specific gravity of samples varied from 2.48 to 2.55. The liquid limit of samples varied between 50% and 60% and plasticity limit varied between 21% and 31%. Based on USCS , fine oil sand tailings samples used in this study should be classed as clay with high plasticity (CH). The experimental apparatus, the testing method and testing procedures used in this study were the same as those used in Suthaker’s study (1995) and Jeeravipoolvarn’s study (2010). The hydraulic conductivity data obtained from this study are presented in Figure 2.10, where it can be found that the hydraulic conductivity decreased by five orders of magnitude when the void ratio decreased from 10 to 1.
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Banded iron formations, pyritic black shale, and gold deposits : a re evaluation

Banded iron formations, pyritic black shale, and gold deposits : a re evaluation

The purpose of this research is to re-evaluate the epigenetic model of ore formation for two iron formation-hosted gold districts, Homestake (USA) and Randalls (Australia), using iron formation and pyritic black shale from the mines (in the case of Homestake) as well as samples of pyritic black shale from the Lucky Bay gold prospect, 10 km W of the Randalls district. Further work on the trace element character of pyrite within the black shale facies has been carried out on one other, non-BIF- hosted orogenic gold deposit, the Golden Mile (Australia). The primary method of analysis has been the laser ablation (LA-ICPMS) imaging technique previously described to determine the trace element contents and zonation within the diagenetic pyrite and iron-rich mesobands of the iron formations and surrounding lithologies, with particular interest in gold and the ore-forming trace element suite. These deposits were selected on the basis of their differing metamorphic grades, with Homestake having the highest metamorphic grade (lower amphibolite facies) and Randalls being the lowest grade district (maximum upper greenschist facies). This spectrum of metamorphic conditions is necessary for unravelling the evolution of these ores. Testing this model at the selected sites (as well as at the Golden Mile greenstone-hosted orogenic Au deposit) has hopefully provided a clearer paragenetic sequence of gold mineralization in BIF-hosted systems than currently exists. Lead isotopes in pyrite (Meffre et al., 2008), conventional and SHRIMP sulfur isotope studies, and whole-rock geochemical analyses have complimented the LA-ICPMS results and help construct a more robust framework for understanding the origins of iron formation-hosted gold ores. Research questions answered in this study include: • Is gold originally concentrated in pyritic carbonaceous shale (‘sulfide-facies BIF’) only, as previous
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