scholarly journals Application of Unconventional Seismic Attributes and Unsupervised Machine Learning for the Identification of Fault and Fracture Network

2020 ◽  
Vol 10 (11) ◽  
pp. 3864 ◽  
Author(s):  
Umar Ashraf ◽  
Hucai Zhang ◽  
Aqsa Anees ◽  
Hassan Nasir Mangi ◽  
Muhammad Ali ◽  
...  
Keyword(s):  
Neural Networks ◽  
Median Filter ◽  
Fracture Network ◽  
Structural Features ◽  
Small Scale ◽  
Fracture Density ◽  
Fracture Characterization ◽  
Field Development ◽  
Fracture Length ◽  
Dip Angle

The identification of small scale faults (SSFs) and fractures provides an improved understanding of geologic structural features and can be exploited for future drilling prospects. Conventional SSF and fracture characterization are challenging and time-consuming. Thus, the current study was conducted with the following aims: (a) to provide an effective way of utilizing the seismic data in the absence of image logs and cores for characterizing SSFs and fractures; (b) to present an unconventional way of data conditioning using geostatistical and structural filtering; (c) to provide an advanced workflow through multi-attributes, neural networks, and ant-colony optimization (ACO) for the recognition of fracture networks; and (d) to identify the fault and fracture orientation parameters within the study area. Initially, a steering cube was generated, and a dip-steered median filter (DSMF), a dip-steered diffusion filter (DSDF), and a fault enhancement filter (FEF) were applied to sharpen the discontinuities. Multiple structural attributes were applied and shortlisted, including dip and curvature attributes, filtered and unfiltered similarity attributes, thinned fault likelihood (TFL), fracture density, and fracture proximity. These shortlisted attributes were computed through unsupervised vector quantization (UVQ) neural networks. The results of the UVQ revealed the orientations, locations, and extensions of fractures in the study area. The ACO proved helpful in identifying the fracture parameters such as fracture length, dip angle, azimuth, and surface area. The adopted workflow also revealed a small scale fault which had an NNW–SSE orientation with minor heave and throw. The implemented workflow of structural interpretation is helpful for the field development of the study area and can be applied worldwide in carbonate, sand, coal, and shale gas fields.

SEEPAGE PROPERTIES OF ROCK FRACTURES WITH POWER LAW LENGTH DISTRIBUTIONS

Fractals ◽  
2019 ◽  
Vol 27 (04) ◽  
pp. 1950057 ◽  
Author(s):  
TONGJUN MIAO ◽  
SUJUN CHENG ◽  
AIMIN CHEN ◽  
YAN XU ◽  
GUANG YANG ◽  
...  
Keyword(s):  
Power Law ◽  
Structural Parameters ◽  
Length Distribution ◽  
Fracture Network ◽  
Analytical Models ◽  
Fracture Density ◽  
Fracture Networks ◽  
Permeability Model ◽  
Fracture Length ◽  
Power Law Exponent

Fractures with power law length distributions abound in nature such as carbonate oil and gas reservoirs, sandstone, hot dry rocks, etc. The fluid transport properties and morphology characterization of fracture networks have fascinated numerous researchers to investigate for several decades. In this work, the analytical models for fracture density and permeability are extended from fractal fracture network to general fracture network with power law length distributions. It is found that the fracture density is related to the power law exponents [Formula: see text] and the area porosity [Formula: see text] of fracture network. Then, a permeability model for the fracture length distribution with general power law exponent [Formula: see text] and the power law exponent [Formula: see text] for fracture length versus aperture is proposed based on the well-known cubic law in individual fracture. The analytical expression for permeability of fractured networks is found to be a function of power law exponents [Formula: see text], area porosity [Formula: see text] of fracture network, and the micro-structural parameters (maximum fracture length [Formula: see text], fracture azimuth [Formula: see text] and fracture dip angle [Formula: see text]). The present model may shed light on the mechanism of seepage in fracture networks with power law length distributions.

scholarly journals Study on the effects of fracture on permeability with pore-fracture network model

2018 ◽  
Vol 36 (6) ◽  
pp. 1556-1565 ◽  
Author(s):  
Chunyan Jiao ◽  
Yong Hu ◽  
Xuan Xu ◽  
Xiaobing Lu ◽  
Weijun Shen ◽  
...  
Keyword(s):  
Network Model ◽  
Fracture Network ◽  
Network Control ◽  
Control Mode ◽  
Fractured Reservoir ◽  
Fracture Density ◽  
Gas Reservoirs ◽  
Fracture Length ◽  
Fracture Development ◽  
The Matrix

Reservoir quality and productivity of fractured gas reservoirs depend heavily on the degree of fracture development. The fracture evaluation of such reservoir media is the key to quantify reservoir characterization for the purposes such as well drilling and completion as well as development and simulation of fractured gas reservoirs. In this study, a pore-fracture network model was constructed to understand the effects of fracture on permeability in the reservoir media. The microstructure parameters of fractures including fracture length, fracture density, fracture number, and fracture radius were analyzed. Then two modes and effects of matrix and fracture network control were discussed. The results indicate that the network permeability in the fractured reservoir media will increase linearly with fracture length, fracture density, fracture number, and fracture radius. When the fracture radius exceeds 80 µm, the fracture radius has a little effect on network permeability. Within the fracture density less than 0.55, it belongs to the matrix control mode, while the fracture network control mode is dominant in the fracture density exceeding 0.55. The network permeability in the matrix and fracture network control modes is affected by fracture density and the ratio of fracture radius to pore radius. There is a great change in the critical density for the matrix network control compared with the fracture network control. This work can provide a better understanding of the relationship between matrix and fractures, and the effects of fracture on permeability so as to evaluate the fluid flow in the fractured reservoir media.

Diffraction imaging in fractured carbonates and unconventional shales

2015 ◽  
Vol 3 (1) ◽  
pp. SF69-SF79 ◽  
Author(s):  
Ioan Sturzu ◽  
Alexander Mihai Popovici ◽  
Tijmen Jan Moser ◽  
Sudha Sudhakar
Keyword(s):  
Natural Fracture ◽  
Small Scale ◽  
Fracture Density ◽  
New Approach ◽  
Field Development ◽  
Time Migration ◽  
The Us ◽  
Diffraction Imaging ◽  
Resolution Imaging ◽  
Shale Reservoirs

Diffraction imaging is recognized as a new approach to image small-scale fractures in shale and carbonate reservoirs. By identifying the areas with increased natural fracture density, reservoir engineers can design an optimal well placement program that targets the sweet spots (areas with increased production), and minimizes the total number of wells used for a prospective area. High-resolution imaging of the small-scale fractures in shale reservoirs such as Eagle Ford, Bakken, Utica, and Woodbine in the US, and Horn River, Montney, and Utica in Canada improves the prospect characterization and predrill assessment of the geologic conditions, improves the production and recovery efficiency, reduces field development cost, and decreases the environmental impact of developing the field by using fewer wells to optimally produce the reservoir. We evaluated several field data examples using a method of obtaining images of diffractors using specularity filtering that could be performed in depth and time migration. Provided that a good migration velocity was available, we used the deviation of ray scattering from Snell’s law to attenuate reflection energy in the migrated image. The resulting diffraction images reveal much of the structural detail that was previously obscured by reflection energy.

scholarly journals Fracture networks in Rotliegend gas reservoirs of the Dutch offshore: implications for reservoir behaviour

2000 ◽  
Vol 79 (1) ◽  
pp. 45-57 ◽  
Author(s):  
B.D.M. Gauthier ◽  
R.C.W.M. Franssen ◽  
S. Drei
Keyword(s):  
Fracture Network ◽  
Development Planning ◽  
Small Scale ◽  
List Type ◽  
Gas Reservoirs ◽  
Positive Role ◽  
Field Development ◽  
Fracture Systems ◽  
Reservoir Flow ◽  
Gas Fields

AbstractFracture systems of Rotliegend gas fields in and at the margins of the northern Broad Fourteens Basin in the Dutch offshore are described in terms of orientation, frequency, origin and type, and in relation to larger-scale structures. First, fracture data collected from core and image logs have been corrected to account for the bias related to the 1-D sampling. Second, these results were integrated with data on fracture cements and diagenesis in order to assess the timing of the fracture network development.On the basis of their regional extent three phases of fracturing and four orientation trends can be distinguished in the basin: (1)at Triassic times and related to early diagenesis and burial, NW-SE to NNW-SSE and NE-SW to ESE-WNW particulate-shear fractures developed;(2)during the Mid-Kimmerian and related to the main burial stage, shear-related and dilational-shear-fault-related fracturing occurred parallel with larger-scale faults;(3)during the Cretaceous and related to uplift, NW-SE and NE-SW joints propagated; a regional joint system developed outside the Jurassic rift basin, preferentially oriented E-W to ESE-WNW; these joints have not been dated accurately.The fault-related shear fractures tend to compartmentalise the reservoirs, whereas the regional joints tend to enhance reservoir flow properties. These fracture systems are thought to play a negative or positive role, respectively, but only in fields with poor reservoir quality. Consequently, in such cases small-scale fractures should be taken into account in field development planning.

scholarly journals Developing a new algorithm for numerical modeling of discrete fracture network (DFN) for anisotropic rock and percolation properties

2021 ◽  
Vol 11 (2) ◽  
pp. 839-856
Author(s):  
Erfan Hosseini ◽  
Mohammad Sarmadivaleh ◽  
Zhongwei Chen
Keyword(s):  
Fractured Rock ◽  
Fracture Network ◽  
Connected Components ◽  
Threshold Condition ◽  
Fracture Density ◽  
Anisotropic Rock ◽  
Fracture Properties ◽  
Fracture Length ◽  
Discrete Fracture ◽  
Dfn Model

AbstractThe role of natural fractures in future reservoir performance is prominent. The fractured porous media is composed of an interconnected network of fractures and blocks of the porous medium where fractures occur in various scales and have a strong influence either when most of the flow is concentrated and them or when they act as barriers. A general numerical model for discrete fracture networks (DFN) is usually employed to handle the observed wide variety of fracture properties and the lack of direct fracture visualization. These models generally use fracture properties’ stochastic distribution based on sparse and seismic data without any physical model constraint. Alternatively, a DFN model includes usual numerical geomechanical approaches like boundary element and finite element. But here, a geostatistical methodology has been used to generate a DFN model. In this paper, an alternative modeling technique is employed to create the realization of an anisotropic fractured rock using simulated annealing (SA) optimization algorithm. There is a notable positive correlation between fracture length and position. There are three principal subjects in a study of fractured rocks. Firstly, the network’s connectivity, secondly, fluid flows through the system, and thirdly, dispersion. Here, connectivity of generated networks is considered. Continuum percolation is the mathematical model to study the geometry of connected components in a random subset of space. Different random realizations from the S.A. algorithm in four different sizes of L = 100, 150, 200, 250 at post-threshold condition are used as disordered media in percolation theory to compute percolation properties using Monte Carlo simulation. The percolation threshold (critical fracture density) and two crucial scaling exponents (β and υ) that dictate the model’s connectivity behavior are estimated to over 200 realizations.

scholarly journals SEISMIC ATTRIBUTES AIDED DETECTION OF NW-SE TRENDING FAULTS DEVELOPED ON AN ISOLATED CARBONATE PLATFORM IN THE NW SIRTE BASIN, NORTH CENTRAL LIBYA

2021 ◽  
Vol 5 (11) ◽  
Author(s):  
Muneer Abdalla
Keyword(s):  
Seismic Data ◽  
Carbonate Platform ◽  
Median Filter ◽  
Random Noise ◽  
Seismic Attributes ◽  
Structural Features ◽  
North Central ◽  
Field Development ◽  
Sirte Basin ◽  
Upper Paleocene

The lower and upper Paleocene reservoir formations, the primary producing formations in the northwest Sirte Basin, north-central Libya have complex structures which have an impact on the performance of the reservoirs. It is extremely crucial to understand the complex relationships between the fault networks and stratigraphy of the area for future field development. However, delineating faults particularly subtle faults is not an easy process due to the low signal-to-noise ratio in the post stack seismic data despite the effort and careful process of the pre-stack data. Seismic attributes are critical tools in detecting and enhancing major and minor fault interpretation beyond the seismic resolution of the conventional seismic dataset. This study utilizes variance, root mean square, and curvature attributes computed from the post-stack 3D seismic data acquired in the northwest Sirte Basin to detect major and minor faults along an isolated carbonate platform. A spectral whitening and median filter were applied to improve the quality of the data and remove random noise resulted from data acquisition and processing steps. Those methods were utilized to provide high-resolution seismic data and better show edges and structural features. Numerous faults have been detected in the study area. Most major faults in the lower and upper Paleocene reservoir formations are located along the margins of the isolated carbonate platform and have a NW-SE trend. Data conditioning and seismic attribute analyses applied on the 3-D seismic dataset effectively enhanced our understanding of the reservoir complexity and improve the detection of the major and minor faults and fracture zones in the study area.

Graph classification based on structural features of significant nodes and spatial convolutional neural networks

2021 ◽  
Vol 423 ◽  
pp. 639-650
Author(s):  
Tinghuai Ma ◽  
Hongmei Wang ◽  
Lejun Zhang ◽  
Yuan Tian ◽  
Najla Al-Nabhan
Keyword(s):  
Neural Networks ◽  
Convolutional Neural Networks ◽  
Structural Features ◽  
Graph Classification

Dual-Permeability Modeling of Capillary Diversion and Drift Shadow Effects in Unsaturated Fractured Rock

2009 ◽  
Vol 131 (10) ◽  
Author(s):  
Clifford K. Ho ◽  
Bill W. Arnold ◽  
Susan J. Altman
Keyword(s):  
Fractured Rock ◽  
Constitutive Relations ◽  
Water Flux ◽  
Fracture Network ◽  
Small Scale ◽  
Grid Refinement ◽  
Capillary Pressures ◽  
And Behavior ◽  
Capillary Pressure Curves ◽  
The Impact

The drift-shadow effect describes capillary diversion of water flow around a drift or cavity in porous or fractured rock, resulting in lower water flux directly beneath the cavity. This paper presents computational simulations of drift-shadow experiments using dual-permeability models, similar to the models used for performance assessment analyses of flow and seepage in unsaturated fractured tuff at Yucca Mountain. Comparisons were made between the simulations and experimental data from small-scale drift-shadow tests. Results showed that the dual-permeability models captured the salient trends and behavior observed in the experiments, but constitutive relations (e.g., fracture capillary-pressure curves) can significantly affect the simulated results. Lower water flux beneath the drift was observed in both the simulations and tests, and fingerlike flow patterns were seen to exist with lower simulated capillary pressures. The dual-permeability models used in this analysis were capable of simulating these processes. However, features such as irregularities along the top of the drift (e.g., from roof collapse) and heterogeneities in the fracture network may reduce the impact of capillary diversion and drift shadow. An evaluation of different meshes showed that at the grid refinement used, a comparison between orthogonal and unstructured meshes did not result in large differences.

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