scholarly journals Natural Fractures Characteristics of the Carboniferous Volcanic Reservoir in Northwestern Margin of Junggar Basin

2021 ◽  
Author(s):  
Bei Lv ◽  
Luo Yao ◽  
Bo Wang ◽  
Jian Wang ◽  
Lizhi Wang
Keyword(s):  
Junggar Basin ◽  
High Conductivity ◽  
Fracture Density ◽  
Natural Fractures ◽  
Fracture Width ◽  
Media Type ◽  
Volcanic Reservoir ◽  
Northwestern Margin ◽  
Regional Tectonic

Research on the regional fracture’s development is important for reservoir fracturing. This paper takes the Carboniferous volcanic reservoir in the northwestern margin of Junggar Basin as the research object. Based on understanding the regional tectonic faults and geological characteristics, the parameter characteristics of natural fractures are analyzed using imaging logging data, and natural fractures distribution characteristics are compared with regional faults and in-situ stresses, as well as the pattern of natural fractures formation is revealed. The results indicated that: (1) The Carboniferous in the northwestern margin of Junggar Basin area mainly develops 3 NE-trending reverse faults. The reservoir type is pore-fracture dual media type, with an average porosity of 7.64% and an average permeability of 1.16mD, which belongs to the medium-porosity and ultra-low permeability reservoir; (2) Reservoir fractures are generally well developed. High-conductivity fractures and high-resistance fractures coexist, but high-conductivity fractures are the main ones. The fracture width is between 0.053 and 0.23 mm, and the fracture density is between 0.5 and 1.68 strips/m. The length is between 0.54-1.88m, the fracture porosity is between 3.4×10-5-41×10-5, and the dominant fracture trend is mainly NE50°-NE80°; (3) The direction of the maximum horizontal in-situ stress of the reservoir is mainly NE30°-NE60°, in the direction of NEE, it differs from fracture strike by 10°-50°, and roughly the same as the strike of the three reverse faults.

High-strength and high-conductivity in situ Cu–TiB2 nanocomposites

2021 ◽  
pp. 141952
Author(s):  
Shuaihang Pan ◽  
Tianqi Zheng ◽  
Gongcheng Yao ◽  
Yitian Chi ◽  
Igor De Rosa ◽  
...  
Keyword(s):  
High Strength ◽  
High Conductivity

scholarly journals 3D finite-element modeling of effective elastic properties for fracture density and multiscale natural fractures

2021 ◽  
Vol 18 (4) ◽  
pp. 567-582
Author(s):  
Shikai Jian ◽  
Li-Yun Fu ◽  
Chenghao Cao ◽  
Tongcheng Han ◽  
Qizhen Du
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Elastic Properties ◽  
Least Square ◽  
P Wave ◽  
Fracture Density ◽  
Equivalent Stiffness ◽  
Natural Fractures ◽  
Effective Elastic Properties ◽  
Element Modeling

Abstract Natural fractures are usually multiscale in size, orientations and distribution, resulting in complex anisotropic characteristics. Analytical methods for quantifying the associated effective elastic properties are based on some assumptions, such as dilute fracture concentration and regular-shaped fractures, which do not occur in actual reservoirs. Here, we conduct anisotropic finite-element modeling of effective elastic properties of complex fractured rocks using the least-square fitting method. The algorithm is developed for a 3D case and validated by classical effective medium theories for models with different fracture densities. The results of the 3D numerical method agree well with the theoretical predictions at low fracture density. The model also considers the interactions among fractures to calculate equivalent stiffness tensors at high fracture density. Three 2D fracture models are simulated to demonstrate the basic behavior of stress interactions and their effect on the overall elasticity under different fracture densities. We applied the developed model to 3D natural fractures built from a real outcrop, and we found that the fracturing pattern significantly affects the effective anisotropy properties. The resultant P-wave phase velocities as functions of the incidence angle and frequency are anisotropic. This study provides a great potential to calculate equivalent stiffness tensors and anisotropic properties of 3D multiscale natural fractures.

scholarly journals Fractures in Volcanic Reservoir: a case study of Zhongguai uplift in Northwestern Margin of Junggar Basin, China

2018 ◽  
Vol 22 (3) ◽  
pp. 169-174 ◽  
Author(s):  
Cunhui Fan ◽  
Qirong Qin ◽  
Feng Liang ◽  
Zenghui Fan ◽  
Zhi Li
Keyword(s):  
Oil And Gas ◽  
Volcanic Rocks ◽  
Junggar Basin ◽  
Pressure Change ◽  
Reservoir Permeability ◽  
Northwestern Margin ◽  
Genetic Mechanisms ◽  
Relationship Of ◽  
Oilfield Development

Fractures in Carboniferous volcanic rocks located at Zhongguai Area (China) highly influence the accumulation and productivity of oil and gas. As such, the study of development periods and genetic mechanisms of tectonic fractures could throw useful information regarding the evaluation and development of that reservoir. Their tectonic origins caused high-angle and oblique shear fractures. The primary orientation of those fractures appears close to EW (270°±10°), NW (300°±15°), NE (45°±15°), and SN (0°±10°). At least four fracture generations can be found in Carboniferous volcanic rocks at Zhongguai Area. Combined with a tectonic evolution, they are based on the segmentation relationship of the fracture fillings, the thermometry measurement of the fracture filling inclusion, and the acoustic emission, as well. Affected by a new horizontal principal stress, the opening and permeability of nearly EW fractures are the best. In this way, a priority in the development of well's patterns should be considered close to EW fractures. The pressure change in the process of exploitation may damage the reservoir permeability of fractured volcano rocks severely. Accordingly, well patterns should be adjusted to dynamic changes of permeability happened during the oilfield development since some differences have been detected in distinct fracture sets. 

Patchy bedrock explained: Tectonic fracture control on landscape evolution patterns in south-Central Chile 

2021 ◽  
Author(s):  
Emma Lodes ◽  
Dirk Scherler ◽  
Hella Wittmann ◽  
Renee Van Dongen
Keyword(s):  
Chemical Weathering ◽  
Landscape Evolution ◽  
Tectonic Deformation ◽  
Fracture Density ◽  
Rock Fracturing ◽  
Central Chile ◽  
Erosion Rates ◽  
Denudation Rates ◽  
South Central

<p>Rock fracturing induced by tectonic deformation is thought to promote faster denudation in more highly fractured areas by lowering grain size and directing the flow of water. That the density and pattern of fractures in a landscape play a role in controlling erosion and landscape evolution has been known for over a century, but not until recently do we have tools, like cosmogenic nuclides, to quantify erosion rates in places with varying fracture densities. In the Nahuelbuta Range in south-central Chile, we observed that >30-m thick regolith exists next to patches of unweathered bedrock. We hypothesize that the density of fractures dictates the pace and patterns of chemical weathering, regolith conversion, and erosion in the Nahuelbuta Range. To test this, we used in situ cosmogenic <sup>10</sup>Be to obtain denudation rates from amalgamated samples of bedrock, corestones and soils, and measured fracture density and orientation, as well as hillslope boulder size in several sites in the Nahuelbuta Range. We found that more highly fractured areas indeed have higher denudation rates than less fractured areas, and that bedrock denudation rates are ~10 m/Myr while soil denudation rates are ~30 m/Myr, suggesting that soil-covered areas may be sites of higher fracture density at depth. Fractures have orientations that match mapped faults across the Nahuelbuta range, and thus are considered to be tectonically-induced. In addition, both fracture and fault orientations match the orientation of streams incising the range, suggesting that fractures control stream channel orientation by weakening bedrock and thus directing flow.</p>

Predicting the azimuth of natural fractures and in-situ horizontal stress: A case study from Sichuan Basin, China

Geophysics ◽  
2021 ◽  
pp. 1-97
Author(s):  
kai lin ◽  
Bo Zhang ◽  
Jianjun Zhang ◽  
Huijing Fang ◽  
Kefeng Xi ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Seismic Data ◽  
Sichuan Basin ◽  
Horizontal Stress ◽  
Seismic Attributes ◽  
Seismic Events ◽  
Natural Fractures ◽  
Microseismic Data ◽  
Maximum Horizontal Stress

The azimuth of fractures and in-situ horizontal stress are important factors in planning horizontal wells and hydraulic fracturing for unconventional resources plays. The azimuth of natural fractures can be directly obtained by analyzing image logs. The azimuth of the maximum horizontal stress σH can be predicted by analyzing the induced fractures on image logs. The clustering of micro-seismic events can also be used to predict the azimuth of in-situ maximum horizontal stress. However, the azimuth of natural fractures and the in-situ maximum horizontal stress obtained from both image logs and micro-seismic events are limited to the wellbore locations. Wide azimuth seismic data provides an alternative way to predict the azimuth of natural fractures and maximum in-situ horizontal stress if the seismic attributes are properly calibrated with interpretations from well logs and microseismic data. To predict the azimuth of natural fractures and in-situ maximum horizontal stress, we focus our analysis on correlating the seismic attributes computed from pre-stack and post-stack seismic data with the interpreted azimuth obtained from image logs and microseismic data. The application indicates that the strike of the most positive principal curvature k1 can be used as an indicator for the azimuth of natural fractures within our study area. The azimuthal anisotropy of the dominant frequency component if offset vector title (OVT) seismic data can be used to predict the azimuth of maximum in-situ horizontal stress within our study area that is located the southern region of the Sichuan Basin, China. The predicted azimuths provide important information for the following well planning and hydraulic fracturing.

scholarly journals New hydrocarbon exploration areas in footwall covered structures in northwestern margin of Junggar Basin

2008 ◽  
Vol 35 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Shu-wei GUAN ◽  
Ben-liang LI ◽  
Lian-hua HOU ◽  
Deng-fa HE ◽  
Xin SHI ◽  
...  
Keyword(s):  
Junggar Basin ◽  
Hydrocarbon Exploration ◽  
Northwestern Margin

scholarly journals Estimating Unpropped-Fracture Conductivity and Fracture Compliance From Diagnostic Fracture-Injection Tests

SPE Journal ◽  
2018 ◽  
Vol 23 (05) ◽  
pp. 1648-1668 ◽  
Author(s):  
HanYi Wang ◽  
Mukul M. Sharma
Keyword(s):  
Earth Science ◽  
Mathematical Framework ◽  
Field Scale ◽  
Time Data ◽  
Fracture Conductivity ◽  
Reliable Technique ◽  
Fracture Width ◽  
In Situ Conditions ◽  
Fracture Closure

Summary A new method is proposed to estimate the compliance and conductivity of induced unpropped fractures as a function of the effective stress acting on the fracture from diagnostic-fracture-injection-test (DFIT) data. A hydraulic-fracture resistance to displacement and closure is described by its compliance (or stiffness). Fracture compliance is closely related to the elastic, failure, and hydraulic properties of the rock. Quantifying fracture compliance and fracture conductivity under in-situ conditions is crucial in many Earth-science and engineering applications but is very difficult to achieve. Even though laboratory experiments are used often to measure fracture compliance and conductivity, the measurement results are influenced strongly by how the fracture is created, the specific rock sample obtained, and the degree to which it is preserved. As such, the results may not be representative of field-scale fractures. During the past 2 decades, the DFIT has evolved into a commonly used and reliable technique to obtain in-situ stresses, fluid-leakoff parameters, and formation permeability. The pressure-decline response across the entire duration of a DFIT reflects the process of fracture closure and reservoir-flow capacity. As such, it is possible to use these data to quantify changes in fracture conductivity as a function of stress. In this paper, we present a single, coherent mathematical framework to accomplish this. We show how each factor affects the pressure-decline response, and the effects of previously overlooked coupled mechanisms are examined and discussed. Synthetic and field-case studies are presented to illustrate the method. Most importantly, a new specialized plot (normalized system-stiffness plot) is proposed, which not only provides clear evidence of the existence of a residual fracture width as a fracture is closing during a DFIT, but also allows us to estimate fracture-compliance (or stiffness) evolution, and infer unpropped fracture conductivity using only DFIT pressure and time data alone. It is recommended that the normalized system-stiffness plot (NS plot) be used as a standard practice to complement the G-function or square-root-of-time plot and log-log plot because it provides very valuable information on fracture-closure behavior and the properties of fracture-surface roughness at a field-scale, information that cannot be obtained by any other means.

NATURAL FRACTURES OF THE SOUTHERN COOPER AND EASTERN WARBURTON BASINS, SOUTH AUSTRALIA

2001 ◽  
Vol 41 (1) ◽  
pp. 201 ◽  
Author(s):  
X. Sun
Keyword(s):  
South Australia ◽  
Open Fractures ◽  
Fracture Density ◽  
Natural Fractures ◽  
High Angle ◽  
Local Structures ◽  
Fracture Systems ◽  
Brittle Sandstone ◽  
Major Fault ◽  
Well Trajectory

A study of the southern Cooper and eastern Warburton Basins has resulted in classifying natural fractures and delineating regional fracture systems and orientations of open and partially open fractures. Firstly, natural fractures have been identified from selected lithological units in 44 wells of the southern Cooper Basin. Open fractures are developed mainly within the brittle Tirrawarra Sandstone. These open fractures are mostly high angle to subvertical, with measured apertures of up to 2 mm. Secondly, natural fractures have been characterised in Warburton Basin cores from 91 wells, 27 of which have dipmeter and/or FMS (Formation Micro- Scanner) logs. Fractures more commonly occur within brittle sandstone, dolomite, grainy limestone and ignimbrite.Two systems of orthogonal, high-angle, regional fracture sets (four fractures) have been identified. They extend across local structures in both basins in South Australia. System I is comprised of a pair of orthogonal fractures, striking NNE–SSW (20–200°) and ESE–WNW (110–290°), while a second pair of orthogonal fracture sets, striking NE–SW (60–240°) and NW–SE (150–330°), characterises System II. Open, steeply dipping SW fractures striking WNW and NW within Systems I and II have been interpreted from core and FMS data in several wells. The results indicate that an optimum well trajectory designed to maximise intersection with open natural fractures should be 200–210° and 240–250°, and possibly also 270–290°. The deviation angle should be 30° from horizontal in the fracture zone due to the high-angle and subvertical fracture dips. A semi-quantitative estimate of fracture density from cores in both basins has been determined: the greatest fracture density is located within major fault zones and structural culminations.

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