scholarly journals Experimental Studies on Shale Cracks and Permeability Evolution Based on Acoustic Emission Monitoring

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Hao Chen ◽  
Hongkui Ge ◽  
Xiaoqiong Wang ◽  
Jianbo Wang ◽  
Shan Wu
Keyword(s):  
Acoustic Emission ◽  
Percolation Threshold ◽  
Microseismic Monitoring ◽  
Permeability Evolution ◽  
Stimulated Reservoir Volume ◽  
Reservoir Volume ◽  
Longmaxi Shale ◽  
Before And After ◽  
Shale Reservoirs ◽  
The Relationship

The matrix permeability of shale reservoirs is extremely low. Therefore, massive volume fracturing is needed to form a complex crack network and get adequate sufficient capacity during the well completion. After fracturing, the effective stimulated reservoir volume (ESRV) is vital for developing shale reservoirs, mainly determined by stimulated reservoir volume (SRV) and the increase in permeability. Microseismic monitoring is widely used in the field to describe the crack shape and determine the SRV, to evaluate the stimulation effect. However, no studies have been conducted on the relationship between microseismic parameters and permeability. Thereby, we conducted uniaxial compression tests on Longmaxi shale samples and measured their changes in porosity and permeability before and after loading combining the microseismic monitoring under a laboratory scale (acoustic emission (AE)). Results show that porosity has little influence on the permeability before and after loading, while the propagation and connection of cracks are the most critical factors. As the loading stress increases, the crack volume and sample connectivity both grow. Besides, for the Longmaxi shale, when the stress is loaded to 30~50% of uniaxial compressive strength (UCS), the cracks start to propagate steadily (dilation), the permeability begins to increase rapidly, and percolation occurs, which indicates that the dilation point is closely related to the percolation threshold. The AE rate and accumulative ringing number both increase when it is larger than the percolation threshold value. The variation of AE characteristics can be used to identify the percolation threshold. Finally, the graphic model including AE parameters, crack, and permeability evolution is established based on the experimental results, which could help us understand the relationship between microseismic parameters and permeability and provide a methodological basis for the ESRV evaluation in the field.

scholarly journals APPLICATION OF FRACTAL GEOMETRY IN EVALUATION OF EFFECTIVE STIMULATED RESERVOIR VOLUME IN SHALE GAS RESERVOIRS

Fractals ◽  
2017 ◽  
Vol 25 (04) ◽  
pp. 1740007 ◽  
Author(s):  
GUANGLONG SHENG ◽  
YULIANG SU ◽  
WENDONG WANG ◽  
FARZAM JAVADPOUR ◽  
MEIRONG TANG
Keyword(s):  
Hydraulic Fracturing ◽  
Shale Gas ◽  
Fractal Geometry ◽  
Fracture Network ◽  
Gas Reservoirs ◽  
Stimulated Reservoir Volume ◽  
Reservoir Volume ◽  
Adsorbed Gas ◽  
Shale Gas Reservoirs ◽  
Shale Reservoirs

According to hydraulic-fracturing practices conducted in shale reservoirs, effective stimulated reservoir volume (ESRV) significantly affects the production of hydraulic fractured well. Therefore, estimating ESRV is an important prerequisite for confirming the success of hydraulic fracturing and predicting the production of hydraulic fracturing wells in shale reservoirs. However, ESRV calculation remains a longstanding challenge in hydraulic-fracturing operation. In considering fractal characteristics of the fracture network in stimulated reservoir volume (SRV), this paper introduces a fractal random-fracture-network algorithm for converting the microseismic data into fractal geometry. Five key parameters, including bifurcation direction, generating length ([Formula: see text]), deviation angle ([Formula: see text]), iteration times ([Formula: see text]) and generating rules, are proposed to quantitatively characterize fracture geometry. Furthermore, we introduce an orthogonal-fractures coupled dual-porosity-media representation elementary volume (REV) flow model to predict the volumetric flux of gas in shale reservoirs. On the basis of the migration of adsorbed gas in porous kerogen of REV with different fracture spaces, an ESRV criterion for shale reservoirs with SRV is proposed. Eventually, combining the ESRV criterion and fractal characteristic of a fracture network, we propose a new approach for evaluating ESRV in shale reservoirs. The approach has been used in the Eagle Ford shale gas reservoir, and results show that the fracture space has a measurable influence on migration of adsorbed gas. The fracture network can contribute to enhancement of the absorbed gas recovery ratio when the fracture space is less than 0.2 m. ESRV is evaluated in this paper, and results indicate that the ESRV accounts for 27.87% of the total SRV in shale gas reservoirs. This work is important and timely for evaluating fracturing effect and predicting production of hydraulic fracturing wells in shale reservoirs.

scholarly journals Understanding the True Stimulated Reservoir Volume in Shale Reservoirs

2017 ◽  
Author(s):  
Maaruf Hussain ◽  
Bilal Saad ◽  
Ardiansyah Negara ◽  
Shuyu Sun
Keyword(s):  
Stimulated Reservoir Volume ◽  
Reservoir Volume ◽  
Shale Reservoirs

Recognition of Fracturing by Stimulated Reservoir Volume (SRV) in Shale Gas Wells

2011 ◽  
Vol 361-363 ◽  
pp. 349-352 ◽  
Author(s):  
Hui Hui Kou ◽  
Wei Dong Liu ◽  
Dong Dong Hou ◽  
Ling Hui Sun
Keyword(s):  
Fracture Network ◽  
Single Fracture ◽  
Well Performance ◽  
Stimulated Reservoir Volume ◽  
Fracture Length ◽  
Reservoir Volume ◽  
Tight Gas Sands ◽  
Well Pattern ◽  
Complex Fracture Network ◽  
Shale Reservoirs

Ultra-low permeability shale reservoir require a large fracture network to maximal well performance. In conventional reservoirs and tight gas sands, single fracture length and conductivity are the key drivers for stimulation performance. In shale reservoirs, where complex fracture network are created, single fracture length and conductivity are insufficient to stimulate. This is the reason for the concept of using stimulated reservoir volume as a correlation parameter for well performance. This paper mainly illustrates perforation with interlaced row well pattern and multi-fracture fracturing technology and refracturing applied in vertical wells. Moreover, it establishes the seepage differential equation of multi-fracture.

Numerical Modeling of Fracture Propagation During Temporary-Plugging Fracturing

SPE Journal ◽  
2019 ◽  
Vol 25 (03) ◽  
pp. 1503-1522 ◽  
Author(s):  
Yushi Zou ◽  
Xinfang Ma ◽  
Shicheng Zhang
Keyword(s):  
Influence Factors ◽  
Injection Pressure ◽  
Natural Fracture ◽  
Hydraulic Fractures ◽  
Pumping Rate ◽  
Stimulated Reservoir Volume ◽  
Reservoir Volume ◽  
Interaction Behavior ◽  
Before And After ◽  
Horizontal Differential Stress

Summary Temporary-plugging fracturing (TPF) is becoming a promising technique for maximizing the stimulated-reservoir volume in tight reservoirs by injecting diverting agents to plug the preferred perforations and/or hydraulic fractures (HFs). Previous work has developed diverting agents and evaluated their blocking efficiency. However, the mechanism and dominant influence factors of HF growth during TPF remain poorly understood to date, which restricts the application of this technique. To understand the problem and help improve the TPF design, this study simulated the HF-propagation process during TPF in a naturally fractured formation using a previously developed 3D discrete-element-method (DEM) -based complex fracture model. Plugged fracture elements with negligible permeability were incorporated into the model to characterize the blocking intervals of diverting agents within HFs. Parameters, including horizontal differential stress (Δσh), natural-fracture (NF) properties, the number of pluggings, plugging positions, and pumping rate, were investigated to determine their effects on the HF/NF-interaction behavior and the resulting HF geometry. The change in injection pressure before and after plugging under different conditions was also recorded in detail. Modeling results show that the HF/NF-interaction behavior might surprisingly change before and after plugging the preferred HF, ranging from HF crossing of NFs to HF opening of NFs. Notably, Δσh is still the most influential geological parameter that governs the HF-growth behavior during TPF. For a moderate Δσh (=8 MPa), the growth of a single planar HF before plugging can be changed easily into a complex HF network (HFN) through opening of NFs after plugging in the target stimulated region (TSR). In this case, the complexity and covering area of the resulting HFN is closely related to the NF density (positive correlation) and plugging positions. However, for a high Δσh (=12 MPa), opening (usually partially) the NFs after plugging is difficult even in formations with a high density of NFs. In such a case, a large volume of fluid, a high pumping rate, and several repeat pluggings during TPF are necessary. The results of this study help to understand the HF-growth mechanism during TPF and help to optimize the treatment design of TPF and to adjust it in a timely manner.

Interrelationships of Marcellus Shale gas production to frac-induced microseismicity, interpreted minor faults and fractures zones, and stimulated reservoir volume, Greene County, Pennsylvania

2016 ◽  
Vol 4 (1) ◽  
pp. T15-T30 ◽  
Author(s):  
Thomas H. Wilson ◽  
Ariel K. Hart ◽  
Pete Sullivan
Keyword(s):  
Hydraulic Fracture ◽  
Marcellus Shale ◽  
Gas Production ◽  
3D Seismic ◽  
Fracture Zones ◽  
Stimulated Reservoir Volume ◽  
Reservoir Volume ◽  
Microseismic Event ◽  
Greene County ◽  
The Relationship

The data we analyzed are from a Marcellus Shale gas field in Greene County, southwestern Pennsylvania. We first investigated the relationship between microseismic event trends and discontinuities extracted from 3D seismic data and their relationship to [Formula: see text]. This analysis was followed by an examination of the relationship of cumulative gas production to radiated energy, stimulated reservoir volume (SRV), and energy density (ED). We have determined that microseismic event trends observed in multiwell hydraulic fracture treatments were similar to the trends of interpreted small faults and fracture zones extracted from 3D seismic coverage of the area. Hydraulic fracture treatments conducted in six laterals produced clusters of microseismic events with an average trend of N51°E and, to a more limited extent, N56°W. The N51°E microseismic event trend coincided closely with the average N52°E trend of interpreted minor faults and fracture zones extracted from the 3D seismic data. That relationship suggested that microseismic events form through reactivation of old faults and fracture zones in response to an easterly trending [Formula: see text]. We also found that variations in gas production correlated with variations in radiated microseismic energy ([Formula: see text] of 0.985), SRV ([Formula: see text] of 0.974), and ED ([Formula: see text] of 0.989). SRV is a measure of the volume of space occupied by induced microseismicity, whereas energy release per unit volume (ED) can be directly related to rupture area created through hydraulic fracture stimulation. We suggest that ED serves as a better estimator of production potential in unconventional shale reservoirs.

Enhancing Spatial Ability Through Sport Practice

2012 ◽  
Vol 33 (2) ◽  
pp. 83-88 ◽  
Author(s):  
David Moreau ◽  
Jérome Clerc ◽  
Annie Mansy-Dannay ◽  
Alain Guerrien
Keyword(s):  
Mental Rotation ◽  
Spatial Representations ◽  
Mental Rotation Test ◽  
Sport Training ◽  
Sport Practice ◽  
Undergraduate University Students ◽  
Before And After ◽  
Cognitive Plasticity ◽  
Reported Data ◽  
The Relationship

This experiment investigated the relationship between mental rotation and sport training. Undergraduate university students (n = 62) completed the Mental Rotation Test ( Vandenberg & Kuse, 1978 ), before and after a 10-month training in two different sports, which either involved extensive mental rotation ability (wrestling group) or did not (running group). Both groups showed comparable results in the pretest, but the wrestling group outperformed the running group in the posttest. As expected from previous studies, males outperformed women in the pretest and the posttest. Besides, self-reported data gathered after both sessions indicated an increase in adaptive strategies following training in wrestling, but not subsequent to training in running. These findings demonstrate the significant effect of training in particular sports on mental rotation performance, thus showing consistency with the notion of cognitive plasticity induced from motor training involving manipulation of spatial representations. They are discussed within an embodied cognition framework.

Klein with Lacan: A Study on the Reception of Lacanian Ideas in Uruguay and Its Effects on Clinical Practices (1955–82)

2020 ◽  
Vol 22 (3) ◽  
pp. 341-361
Author(s):  
Gonzalo Grau-Pérez ◽  
J. Guillermo Milán
Keyword(s):  
Clinical Practice ◽  
Clinical Material ◽  
Clinical Practices ◽  
Before And After ◽  
The Difference ◽  
The 1960S ◽  
The Relationship ◽  
Discursive Approach ◽  
The Way ◽  
Clinical Cases

In Uruguay, Lacanian ideas arrived in the 1960s, into a context of Kleinian hegemony. Adopting a discursive approach, this study researched the initial reception of these ideas and its effects on clinical practices. We gathered a corpus of discursive data from clinical cases and theoretical-doctrinal articles (from the 1960s, 1970s and 1980s). In order to examine the effects of Lacanian ideas, we analysed the difference in the way of interpreting the clinical material before and after Lacan's reception. The results of this research illuminate some epistemological problems of psychoanalysis, especially the relationship between theory and clinical practice.

The influence of ultrasound signal parameters on sonoluminescence light intensity

2013 ◽  
Vol 62 (4) ◽  
pp. 605-612
Author(s):  
Marek Szmechta ◽  
Tomasz Boczar ◽  
Dariusz Zmarzły
Keyword(s):  
Acoustic Emission ◽  
Acoustic Waves ◽  
Power Transformer ◽  
Electrical Power ◽  
Partial Discharges ◽  
Research Project ◽  
Insulation Systems ◽  
Secondary Phenomenon ◽  
New Research ◽  
The Relationship

Abstract Topics of this article concern the study of the fundamental nature of the sonoluminescence phenomenon occurring in liquids. At the Institute of Electrical Power Engineering at Opole University of Technology the interest in that phenomenon known as secondary phenomenon of cavitation caused by ultrasound became the genesis of a research project concerning acoustic cavitation in mineral insulation oils in which a number of additional experiments performed in the laboratory aimed to determine the influence of a number of acoustic parameters on the process of the studied phenomenona. The main purpose of scientific research subject undertaken was to determine the relationship between the generation of partial discharges in high-voltage power transformer insulation systems, the issue of gas bubbles in transformer oils and the generated acoustic emission signals. It should be noted that currently in the standard approach, the phenomenon of generation of acoustic waves accompanying the occurrence of partial discharges is generally treated as a secondary phenomenon, but it can also be a source of many other related phenomena. Based on our review of the literature data on those referred subjects taken, it must be noted, that this problem has not been clearly resolved, and the description of the relationship between these phenomena is still an open question. This study doesn’t prove all in line with the objective of the study, but can be an inspiration for new research project in the future in this topic. Solution of this problem could be a step forward in the diagnostics of insulation systems for electrical power devices based on non-invasive acoustic emission method.

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