scholarly journals Advances in Laboratory-Scale Hydraulic Fracturing Experiments

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Yelin Qian ◽  
Panpan Guo ◽  
Yixian Wang ◽  
Yanlin Zhao ◽  
Hang Lin ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Laboratory Scale ◽  
Future Research ◽  
Accurate Estimation ◽  
Hydraulic Fractures ◽  
Scaling Analysis ◽  
Research Attention ◽  
Complete Control ◽  
Geological Conditions ◽  
Fracturing Experiments

Hydraulic fracturing has been widely applied to stimulate the natural gas and oil production from unconventional reservoirs. To optimize the design of hydraulic fracturing in this application, an accurate estimation of the initiation and propagation of hydraulic fractures is indispensable. However, it still remains challenging as a result of the complex stress state and geological conditions. On account of their ability to complete control some significant factors and efficient observation of fracture geometry, laboratory-scale hydraulic fracturing experiments have received abundant research attention in recent years. This paper presents a review of the state of the art of laboratory-scale hydraulic fracturing experiments, focusing on the scaling analysis, experimental setup, fracturing fluids, and sample preparation. A discussion of the directions for future research is also provided with the intention of stimulating the development of the experimental technique for investigating hydraulic fracturing.

scholarly journals Methodological approach to optimal geological and technological characteristics determining when planning hydraulic fracturing at multilayer facilities

2021 ◽  
pp. 182-191
Author(s):  
V. A. Grishchenko ◽  
◽  
R. U. Rabaev ◽  
I. N. Asylgareev ◽  
V. Sh. Mukhametshin ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Methodological Approach ◽  
Oil Fields ◽  
Hydraulic Fractures ◽  
Reservoir Properties ◽  
Effective Power ◽  
Stage Of Development ◽  
Technological Characteristics ◽  
Specific Loading ◽  
Geological Conditions

The paper considers the issue of increasing the hydraulic fracturing efficiency in a multilayer facility at the final stage of development with an uneven degree of reserves development along the section. Based on the results of the analysis, it was found that the upper layers, which have the worst filtration-reservoir properties, are less developed in comparison with the highly productive lower ones. When hydraulic fracturing was carried out in the upper formations, some of the operations had low success due to the breakthrough of hydraulic fractures into the lower depleted formations. On the basis of the revealed dependencies, the work determined the optimal specific loading of proppant per meter of effective power, depending on the geological conditions, and maps of the prospects for hydraulic fracturing are built. Keywords: oil fields development; hydraulic fracturing; hydraulic fracturing optimization; multilayer facilities.

Proppant Transport in Hydraulic Fractures by Creating a Capillary Suspension

2021 ◽  
Author(s):  
Ayomikun Bello
Keyword(s):  
Hydraulic Fracturing ◽  
Significant Risk ◽  
High Viscosity ◽  
Hydraulic Fractures ◽  
Main Task ◽  
Low Viscosity ◽  
Fracturing Fluids ◽  
Geological Conditions ◽  
Fracture Development ◽  
The Impact

Abstract Slick water fracturing fluids with high viscosity and minimal friction pressure losses are commonly employed in hydraulic fracturing nowadays. At the same time, high injection rates can be used to perform hydraulic fracturing to get the calculated fracture sizes. The conventional algorithm for conducting a standard proppant hydraulic fracturing includes performing a pressure test using a linear gel without a trial proppant pack to determine the quality of communication with the formation and the initial parameters of the fracture; and performing a mini-hydraulic fracturing on a cross-linked gel with a trial proppant pack (1000 - 2000 kg) to assess the parameters of the fracture development used to correct the design of the main hydraulic fracturing operation. However, in complex geological conditions associated with the presence of small clay barriers between the target formation and above or below the water-saturated layers, as well as in low-productive formations, this conventional method of conducting hydraulic fracturing operations using high-viscosity fluids is not always suitable. Hydraulic fracturing in thin-layer formations is associated with a significant risk of the tightness established by the fracture being broken, as well as fluids contained in the underlying or overlying layers being involved in the drainage process. Hydraulic fracturing in low-productive formations creates fractures that are similar in shape to radial fractures, reducing the efficiency and profitability of the impact due to inefficient use of materials and reagents. The main task in this situation is to limit the height of the fracture development and increase their length. It is necessary to use low-viscosity fracturing fluids with a high ability to transfer proppants to reduce the specific pressure in the fracture and control the height of the rupture. The goal of this research is to develop such fluid.

scholarly journals Investigation of the Fracturing Effect Induced by the Disturbing Stress of Hydrofracturing Using the Bonded-Particle Model

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-24
Author(s):  
Xin Zhang ◽  
Yuqi Zhang ◽  
Bingxiang Huang
Keyword(s):  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Fracture Zone ◽  
Fracture Propagation ◽  
Bedding Plane ◽  
Particle Model ◽  
Hydraulic Fractures ◽  
Bedding Planes ◽  
Geological Conditions ◽  
Hydraulic Fracture Propagation

Hydraulic fracturing applications have shown a stress disturbance effect during hydraulic fracture propagation, which is often ignored. Using laboratory and discrete element numerical simulation tests, hydraulic fracture propagation under this stress disturbance is systematically studied. The results show that during hydraulic fracturing, the bedding plane is damaged by the stress disturbance, forming a bedding fracture zone (BFZ). The nonlinear fracture characteristics of the formation process of the disturbed fracture zone are revealed, and two indexes (the number of fractures in the disturbed fracture zone and the size of the disturbed fracture zone) are proposed to evaluate the fracturing effect of the stress disturbance. Based on these indexes, multifactor sensitivity tests are conducted under different geological conditions and operational factors. When the principal stress ( σ 1 ) difference is large, the number of hydraulic fractures gradually decreases from many to one, and the direction of the hydraulic fractures gradually approaches the vertical direction of σ 3 , but the change in the in situ stress condition has no obvious effect on the stress disturbance effect. The weaker the bonding strength of the bedding plane, the more significant the stress disturbance effect is, and the easier it is for the fractures to expand along the bedding plane. With increasing injection rate, the stress disturbance effect first increases and then decreases, and the hydraulic fracture propagates from along the bedding plane to cross the bedding plane. With increasing relative distance between the injection hole and bedding plane, the stress disturbance effect presents a linearly increasing trend, and the hydraulic fractures along the bedding planes extend. Based on the experimental results, the relationship between the fracturing effect of the stress disturbance and the extension mode of the hydraulic fracture is determined, and an optimization method for hydraulic fracturing in composite rock reservoirs is given. The research results can provide a theoretical basis for controlling the formation of complex fracture networks in composite rock reservoirs.

Chemically-Induced Pressure Pulse: Fracturing Competent Reservoirs

2021 ◽  
Author(s):  
Ayman R. Al-Nakhli ◽  
Zeeshan Tariq ◽  
Mohamed Mahmoud ◽  
Abdulazeez Abdulraheem
Keyword(s):  
Hydraulic Fracturing ◽  
Rock Fracture ◽  
Applied Pressure ◽  
Hydraulic Fractures ◽  
Breakdown Pressure ◽  
Hydrocarbon Production ◽  
Fracture Pressure ◽  
Micro Cracks ◽  
Chemically Induced ◽  
Fracturing Experiments

Abstract Commercial volumes of hydrocarbon production from tight unconventional reservoirs need massive hydraulic fracturing operations. Tight unconventional formations are typically located inside deep and over-pressured formations where the rock fracture pressure with slickwater becomes so high because of huge in situ stresses. Therefore, several lost potentials and failures were recorded because of high pumping pressure requirements and reservoir tightness. In this study, thermochemical fluids are introduced as a replacement for slickwater. These thermochemical fluids are capable of reducing the rock fracture pressure by generating micro-cracks and tiny fractures along with the main hydraulic fractures. Thermochemical upon reaction can generate heat and pressure simultaneously. In this study, several hydraulic fracturing experiments in the laboratory on different synthetic cement samples blocks were carried out. Cement blocks were made up of several combinations of cement and sand ratios to simulate real rock scenarios. Results showed that fracturing with thermochemical fluids can reduce the breakdown pressure of the cement blocks by 30%, while applied pressure was reduced up to 88%, when using thermochemical fluid, compared to slickwater. In basins with excessive tectonic stresses, the current invention can become an enabler to fracture and stimulate well stages which otherwise left untreated. A new methodology is developed to lower the breakdown pressure of such reservoirs, and enable fracturing. Keywords: Unconventional formation; breakdown pressure; thermochemicals; micro fractures.

scholarly journals Laboratory-Scale Hydraulic Fracturing Experiments Using Super-Critical State Carbon Dioxide, Water and Viscous Oil

2015 ◽  
Vol 131 (4) ◽  
pp. 115-121
Author(s):  
Tsuyoshi ISHIDA ◽  
Yuya NAGAYA ◽  
Shuhei INUI ◽  
Ziad BENNOUR ◽  
Youqing CHEN ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Hydraulic Fracturing ◽  
Critical State ◽  
Laboratory Scale ◽  
Viscous Oil ◽  
Fracturing Experiments

A Case Study Using Integrated Multi Disciplinary Approach to Model Microseismic Events During Stimulation

2021 ◽  
Author(s):  
Ghazal Izadi ◽  
Colleen Barton ◽  
Pierre-Francois Roux ◽  
Tebis Llobet ◽  
Thiago Pessoa ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Fracture Propagation ◽  
Natural Fracture ◽  
Fracture Model ◽  
Hydraulic Fractures ◽  
Natural Fractures ◽  
Unconventional Reservoir ◽  
Geological Conditions ◽  
Source Mechanisms

Abstract For tight reservoirs where hydraulic fracturing is required to enable sufficient fluid mobility for economic production, it is critical to understand the placement of induced fractures, their connectivity, extent, and interaction with natural fractures within the system. Hydraulic fracture initiation and propagation mechanisms are greatly influenced by the effect of the stress state, rock fabric and pre-existing features (e.g. natural fractures, faults, weak bedding/laminations). A pre-existing natural fracture system can dictate the mode, orientation and size of the hydraulic fracture network. A better understanding of the fracture growth phenomena will enhance productivity and also reduce the environmental footprint as less fractures can be created in a much more efficient way. Assessing the role of natural fractures and their interaction with hydraulic fractures in order to account for them in the hydraulic fracture model is achieved by leveraging microseismicity. In this study, we have used a combination of borehole and surface microseismic monitoring to get high vertical resolution locations and source mechanisms. 3D numerical modelling of hydraulic fracturing in complex geological conditions to predict fracture propagation is essential. 3D hydraulic fracturing simulation includes modelling capabilities of stimulation parameters, true 3D fracture propagation with near wellbore 3D complexity including a coupled DFN and the associated microseismic event generation capability. A 3D hydraulic fracture model was developed and validated by matching model predictions to microseismic observations. Microseismic source mechanisms are leveraged to determine the location and geometry of pre-existing features. In this study, we simulate a DFN based on the recorded seismicity of multi stage hydraulic fractures in a horizontal well. The advanced 3D hydraulic fracture modelling software can integrate effectively and efficiently data from a variety of multi-disciplinary sources and scales to create a subsurface characterization of the unconventional reservoir. By incorporating data from 3D seismic, LWD/wireline, core, completion/stimulation monitoring, and production, the software generates a holistic reservoir model embedded in a modular, multi-physics software platform of coupled numerical solvers that capture the fundamental physics of the processes being modelled. This study illustrates the importance of a powerful software tool that captures the necessary physics of stimulation to predict the effects of various completion designs and thereby ensure the most accurate representation of an unconventional reservoir response to a stimulation treatment.

scholarly journals Multifractal Analysis of Acoustic Emissions during Hydraulic Fracturing Experiments under Uniaxial Loading Conditions: A Niutitang Shale Example

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Jingqiang Tan ◽  
Jun Xie ◽  
Lei Li ◽  
Qiao Lyu ◽  
Jianqiang Han ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Multifractal Analysis ◽  
Uniaxial Loading ◽  
Hydraulic Fractures ◽  
Time Frequency ◽  
Fracturing Process ◽  
Fracturing Experiments ◽  
Fracture Scale ◽  
Ae Signals ◽  
Multifractal Method

Fracture characterization is essential for estimating the stimulated reservoir volume and guiding subsequent hydraulic fracturing stimulations in shale reservoirs. Laboratory fracturing experiments can help provide theoretical and technical guidance for field operations. In this study, hydraulic fracturing experiments on the shale samples from Niutitang Formation in Hunan Province (China) under a uniaxial loading condition are conducted. The multifractal method is used to analyze the acoustic emission (AE) signals and characterize fracture initiation and propagation. The hydraulic fracturing process can be divided into three stages based on the characteristics of AE signals: the initial stage, the quite stage, and the fracturing stage. The multifractal analysis results showed that: (1) the value of the spectrum width, Δα, continues to increase as the energy accumulates until the fracturing stage starts; and (2) the difference in the multifractal spectrum values, Δf, reflects the relationship between small and large signal frequencies and can quantify the fracture scale, i.e., the lower the Δf, the larger the fracture scale and vice versa. The results were further verified using a time-frequency analysis of the AE signals and micro-CT scanning of the samples. This study demonstrates that the multifractal method is feasible for quantitatively characterizing hydraulic fractures and can aid field hydraulic fracturing operations.

scholarly journals Social exclusion increases the executive function of attention networks

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Huoyin Zhang ◽  
Shiyunmeng Zhang ◽  
Jiachen Lu ◽  
Yi Lei ◽  
Hong Li
Keyword(s):  
Social Exclusion ◽  
Executive Control ◽  
Brain Regions ◽  
Negative Influence ◽  
Future Research ◽  
Research Attention ◽  
Attention Network ◽  
Attention Networks ◽  
The Social ◽  
And Control

AbstractPrevious studies in humans have shown that brain regions activating social exclusion overlap with those related to attention. However, in the context of social exclusion, how does behavioral monitoring affect individual behavior? In this study, we used the Cyberball game to induce the social exclusion effect in a group of participants. To explore the influence of social exclusion on the attention network, we administered the Attention Network Test (ANT) and compared results for the three subsystems of the attention network (orienting, alerting, and executive control) between exclusion (N = 60) and inclusion (N = 60) groups. Compared with the inclusion group, the exclusion group showed shorter overall response time and better executive control performance, but no significant differences in orienting or alerting. The excluded individuals showed a stronger ability to detect and control conflicts. It appears that social exclusion does not always exert a negative influence on individuals. In future research, attention to network can be used as indicators of social exclusion. This may further reveal how social exclusion affects individuals' psychosomatic mechanisms.

Sign in / Sign up

Export Citation Format

Share Document