共查询到20条相似文献，搜索用时 453 毫秒
1.
S. Seifollahi P. A. Dowd C. Xu A. Y. Fadakar 《Rock Mechanics and Rock Engineering》2014,47(4):1225-1235
Fracture network modelling plays an important role in many application areas in which the behaviour of a rock mass is of interest. These areas include mining, civil, petroleum, water and environmental engineering and geothermal systems modelling. The aim is to model the fractured rock to assess fluid flow or the stability of rock blocks. One important step in fracture network modelling is to estimate the number of fractures and the properties of individual fractures such as their size and orientation. Due to the lack of data and the complexity of the problem, there are significant uncertainties associated with fracture network modelling in practice. Our primary interest is the modelling of fracture networks in geothermal systems and, in this paper, we propose a general stochastic approach to fracture network modelling for this application. We focus on using the seismic point cloud detected during the fracture stimulation of a hot dry rock reservoir to create an enhanced geothermal system; these seismic points are the conditioning data in the modelling process. The seismic points can be used to estimate the geographical extent of the reservoir, the amount of fracturing and the detailed geometries of fractures within the reservoir. The objective is to determine a fracture model from the conditioning data by minimizing the sum of the distances of the points from the fitted fracture model. Fractures are represented as line segments connecting two points in two-dimensional applications or as ellipses in three-dimensional (3D) cases. The novelty of our model is twofold: (1) it comprises a comprehensive fracture modification scheme based on simulated annealing and (2) it introduces new spatial approaches, a goodness-of-fit measure for the fitted fracture model, a measure for fracture similarity and a clustering technique for proposing a locally optimal solution for fracture parameters. We use a simulated dataset to demonstrate the application of the proposed approach followed by a real 3D case study of the Habanero reservoir in the Cooper Basin, Australia. 相似文献
2.
Fracture network modeling is an essential part of the design, development and performance assessment of Enhanced Geothermal Systems. These systems are created from geothermal resources, usually located several kilometers below the surface of the Earth, by establishing a network of connected fractures through which fluid can flow. The depth of the reservoir makes it impossible to make direct measurements of fractures and data are collected from indirect measurements such as geophysical surveys. An important source of indirect data is the seismic event point cloud generated by the fracture stimulation process. Locations of these points are estimated from recorded micro-seismic signals generated by fracture initiation, propagation and slip. This point cloud can be expressed as a set of three-dimensional coordinates with attributes, for example Se ijk ={(x,y,z);?a|x,y,z∈R,?a∈I}. We describe two methods for reconstructing realistic fracture trace lines and planes given the point cloud of seismic events data: Enhanced Brute-Force Search and RANSAC. The methods have been tested on a synthetic data set and on the Habanero data set of Geodynamics’ geothermal project in the Cooper Basin of South Australia. Our results show that the RANSAC method is an efficient and suitable method for the conditional simulation of fracture networks. 相似文献
3.
Fractures and fracture networks are the fundamental components of enhanced geothermal systems and determine their technical and economic viability. A realistic fracture model that can adequately describe a fracture-stimulated reservoir is critical for subsequent flow and heat transfer analyses of the system. Fractures in these systems are essentially the product of hydraulic stimulations of the reservoir that, together with ground conditions and the local stress regime, determine how fractures are formed and propagated. This paper describes three methods for generating realistic fracture models for enhanced geothermal systems; two of them incorporate the fracture propagation process in the modelling and hence provide a stochastic fracture propagation model. The methods are: a Bayesian framework in the form of Markov Chain Monte Carlo simulation, an extended Random Sampling Consensus model and a Point and Surface Association Consensus model. The conditioning data used in these methods are seismic events recorded during fracture stimulation. Geodynamics’ Habanero reservoir in the Cooper Basin of South Australia is used as a case study to test these methods. 相似文献
4.
C. Danis C. O'Neill M. Lackie L. Twigg A. Danis 《Australian Journal of Earth Sciences》2013,60(5):517-542
A detailed deep 3D geological model is an important basis for many types of exploration and resource modelling. Renewed interest in the structure of the Sydney Basin, driven primarily by sequestration studies, geothermal studies and coal seam gas exploration, has highlighted the need for a model of deep basin geology, structure and thermal state. Here, we combine gravity modelling, seismic reflection surveys, borehole drilling results and other relevant information to develop a deep 3D geological model of the Sydney Basin. The structure of the Sydney Basin is characteristic of a typical intracontinental rift basin, with a deep north–south orientated channel in the Lachlan Fold Belt basement, filled with up to 4 km of rift volcanics, and overlain with Permo-Triassic sediments up to 4 km thick. The deep regional architecture presented in this study will form the framework for more detailed geological, hydrological and geothermal models. 相似文献
5.
Geometric modelling and object-oriented software concepts applied to a heterogeneous fractured network from the Grimsel rock laboratory 总被引：2，自引：0，他引：2
Thomas Kalbacher Ralph Mettier Chris McDermott Wenqing Wang Georg Kosakowski Takeo Taniguchi Olaf Kolditz 《Computational Geosciences》2007,11(1):9-26
Discrete fracture network simulations are computationally intensive and usually time-consuming to construct and configure.
This paper presents a case study with techniques for building a 3D finite element model of an inhomogeneous fracture network
for modelling flow and tracer transport, combining deterministic and stochastic information on fracture aperture distributions.
The complex intersected fractures represent a challenge for geometrical model design, mesh quality requirements and property
allocations. For the integrated and holistic modelling approach, including the application of numerical and analytical simulation
techniques, new object-oriented concepts in software engineering are implemented to ensure a resourceful and practicable software
environment. 相似文献
6.
Yongquan Hu Zhiqiang Li Jinzhou Zhao Zhengwu Tao Pan Gao 《Environmental Earth Sciences》2017,76(15):546
The ultra-low-permeability shale gas reservoir has a lot of well-developed natural fractures. It has been proven that hydraulic fracture growth pattern is usually a complex network fracture rather than conventional single planar fractures by micro-seismic monitoring, which can be explained as the shear and tensile failure of natural fractures or creation of new cracks due to the increase in reservoir pore pressure caused by fluid injection during the process of hydraulic fracturing. In order to simulate the network fracture growth, a mathematical model was established based on full tensor permeability, continuum method and fluid mass conservation equation. Firstly, the governing equation of fluid diffusivity based on permeability tensor was solved to obtain the reservoir pressure distribution. Then Mohr–Coulomb shear failure criterion and tensile failure criterion were used to decide whether the rock failed or not in any block on the basis of the calculated reservoir pressure. The grid-block permeability was modified according to the change of fracture aperture once any type of rock failure criterion was met within a grid block. Finally, the stimulated reservoir volume (SRV) zone was represented by an enhancement permeability zone. After calibrating the numerical solution of the model with the field micro-seismic information, a sensitivity study was performed to analyze the effects of some factors including initial reservoir pressure, injection fluid volume, natural fracture azimuth angle and horizontal stress difference on the SRV (shape, size, bandwidth and length). The results show that the SRV size increases with the increasing initial pore reservoir and injection fluid volume, but decreases with the increase in the horizontal principal stress difference and natural fracture azimuth angle. The SRV shape is always similar for different initial pore reservoir and injection fluid volume. The SRV is observed to become shorter in length and wider in bandwidth with the decrease in natural fracture azimuth angle and horizontal principal stress difference. 相似文献
7.
水力压裂是青海共和盆地干热岩地热资源开发的难点技术问题之一。本文基于升级改造的大尺寸真三轴水力压裂物理模拟实验系统模拟干热岩储层高温高压环境,利用青海共和盆地露头岩心进行水力压裂物理模拟实验,揭示干热岩储层水力裂缝的起裂和扩展规律。通过物理模拟实验发现：干热岩储层裂缝起裂可以通过文中提出的起裂模型判断起裂方式和预测起裂压力;水力裂缝在岩石基质中的扩展形态简单,仅沿最大主应力方向延伸;但是水力裂缝会受到岩石中弱面的影响,发生转向沿弱面延伸,形成较复杂的裂缝形态。因此,建议在干热岩储层实际施工中,在天然裂缝发育较丰富的层段开展水力压裂,以实现复杂裂缝网络提取地热能。 相似文献
8.
论述压裂过程中诱发微地震的激发机理,分析人造裂缝与地应力关系并叙述了微震事件的定位方法。利用微地震监测技术,通过实时定位理论系统对深凹区BYHF1井页岩水平井分段大型压裂过程实时监测,运用偶极子测井和VSP资料建立监测井区的初始速度模型,并通过射孔炮对其校正。在对实时监测定位理论系统数据进行综合处理分析,及有效微震事件识别的基础上,利用纵波和横波信息分析计算得到微地震事件的位置,通过可视化技术对压裂井区裂缝发育的方向、大小、空间分布进行了描述,监测结果是裂缝发育方向基本上为NE34°,与成像测井结果吻合良好。 相似文献
9.
A strategy to predict strain across geological structures, based on previous techniques, is modified and evaluated, and a practical application is shown. The technique, which employs cross-section restoration combined with kinematic forward modelling, consists of restoring a section, placing circular strain markers on different domains of the restoration, and forward modelling the restored section with strain markers until the present-day stage is reached. The restoration algorithm employed must be also used to forward model the structure. The ellipses in the forward modelled section allow determining the strain state of the structure and may indirectly predict orientation and distribution of minor structures such as small-scale fractures. The forward model may be frozen at different time steps (different growth stages) allowing prediction of both spatial and temporal variation of strain. The method is evaluated through its application to two stages of a clay experiment, that includes strain markers, and its geometry and deformation history are well documented, providing a strong control on the results. To demonstrate the method's potential, it is successfully applied to a depth-converted seismic profile in the Central Sumatra Basin, Indonesia. This allowed us to gain insight into the deformation undergone by rollover anticlines over listric normal faults. 相似文献
10.
This paper addresses the problem of explicit fractured media modelling in an operational case. On one side, realistic fracture models are mainly used for research purposes in order to investigate better the flow behaviour impacted by the complex multi-scale fracture network. Often, a very fine grid and hence an increased computation time are needed. On the other hand, an operational fractured reservoir is still generally modelled using an implicit fracture media representation. The upscaled petrophysical properties and dual media are defined on a coarse grid to limit the computational time of dynamic simulation. The challenge of this work is to demonstrate that an explicit fracture modelling is not reserved only for the research domain, but can be applied to an operational case study. The static model is constructed using a multiple point statistics approach in order to represent complex interaction patterns of fractures and faults observed at the analogue outcrop. The dynamic behaviour is simulated based on this spatial fracture network representation. 相似文献
11.
地热资源是一种新型无污染能源,具有极高的开采价值,已经受到世界各国的关注.盆地因其特殊的地质条件,内部往往蕴涵着丰富的地热资源,且具有易开采、利用的特点.但目前地热资源勘探的手段和研究方法单一,制约着地热资源的开采与开发.而盆地地热场模拟技术已经较为成熟,并在油气成藏模拟中广泛应用.我们可以在已有的技术手段下结合盆地地热模拟技术来提高勘探的精度.本文还探讨了以地温控制方程与地下热水水流方程相结合来建立模型,模拟盆地地热资源. 相似文献
12.
Reliable 3D modelling of underground hydrocarbon reservoirs is a challenging task due to the complexity of the underground geological formations and to the availability of different types of data that are typically affected by uncertainties.In the case of geologically complex depositional environments,such as fractured hydrocarbon reservoirs,the uncertainties involved in the modelling process demand accurate analysis and quantification in order to provide a reliable confidence range of volumetric estimations.In the present work,we used a 3D model of a fractured carbonate reservoir and populated it with different lithological and petrophysical properties.The available dataset also included a discrete fracture network(DFN)property that was used to model the fracture distribution.Uncertainties affecting lithological facies,their geometry and absolute positions(related to the fault system),fracture distribution and petrophysical properties were accounted for.We included all different types of uncertainties in an automated approach using tools available in today's modelling software packages and combining all the uncertain input parameters in a series of statistically representative geological realizations.In particular,we defined a specific workflow for the definition of the absolute permeability according to an equivalent,single porosity approach,taking into account the contribution of both the matrix and the fracture system.The results of the analyses were transferred into a 3D numerical fluid-dynamic simulator to evaluate the propagation of the uncertainties associated to the input data down to the final results,and to assess the dynamic response of the reservoir following a selected development plan.The"integrated approach"presented in this paper can be useful for all technicians involved in the construction and validation of 3D numerical models of hydrocarbon-bearing reservoirs and can potentially become part of the educational training for young geo-scientists and engineers,since an integrated and well-constructed workflow is the backbone of any reservoir study. 相似文献
13.
The Development of a new Numerical Modelling Approach for Naturally Fractured Rock Masses 总被引：1，自引：3，他引：1
Summary. An approach for modelling fractured rock masses has been developed which has two main objectives: to maximise the quality
of representation of the geometry of existing rock jointing and to use this within a loading model which takes full account
of this style of jointing. Initially the work has been applied to the modelling of mine pillars and data from the Middleton
Mine in the UK has been used as a case example. However, the general approach is applicable to all aspects of rock mass behaviour
including the stress conditions found in hangingwalls, tunnels, block caving, and slopes. The rock mass fracture representation
was based on a combination of explicit mapping of rock faces and the synthesis of this data into a three-dimensional model,
based on the use of the FracMan computer model suite. Two-dimensional cross sections from this model were imported into the
finite element computer model, ELFEN, for loading simulation.
The ELFEN constitutive model for fracture simulation includes the Rotating Crack, and Rankine material models, in which fracturing
is controlled by tensile strength and fracture energy parameters. For tension/compression stress states, the model is complemented
with a capped Mohr-Coulomb criterion in which the softening response is coupled to the tensile model. Fracturing due to dilation
is accommodated by introducing an explicit coupling between the inelastic strain accrued by the Mohr-Coulomb yield surface
and the anisotropic degradation of the mutually orthogonal tensile yield surfaces of the rotating crack model. Pillars have
been simulated with widths of 2.8, 7 and 14 m and a height of 7 m (the Middleton Mine pillars are typically 14 m wide and
7 m high). The evolution of the pillar failure under progressive loading through fracture extension and creation of new fractures
is presented, and pillar capacities and stiffnesses are compared with empirical models. The agreement between the models is
promising and the new model provides useful insights into the influence of pre-existing fractures. Further work is needed
to consider the effects of three-dimensional loading and other boundary condition problems. 相似文献
14.
Moment tensors and micromechanical models 总被引：4，自引：0，他引：4
A numerical modelling approach that simulates cracking and failure in rock and the associated seismicity is presented and a technique is described for quantifying the seismic source mechanisms of the modelled events. The modelling approach represents rock as an assemblage of circular particles bonded together at points of contact. The connecting bonds can break under applied stress forming cracks and fractures in the modelled rock. If numerical damping is set to reproduce realistic levels of attenuation, then energy is released when the bonds break and seismic source information can be obtained as damage occurs. A technique is described by which moment tensors and moment magnitudes can be calculated for these simulated seismic events. The technique basically involves integrating around the source and summing the components of force change at the surrounding particle contacts to obtain the elements of the moment tensor matrix. The moment magnitude is then calculated from the eigenvalues of the moment tensor. The modelling approach is tested by simulating a well-controlled experiment in which a tunnel is excavated in highly stressed granite while microseismicity is recorded. The seismicity produced by the model is compared to the actual recorded seismicity underground. The model reproduces the spatial and temporal distribution of seismicity observed around the tunnel and also the magnitudes of the events. A direct comparison between the actual and simulated moment tensors is not performed due to the two-dimensional nature of the model, however, qualitative comparisons are presented and it is shown that the model produces intuitively realistic source mechanisms. The ability to obtain seismic source information from the models provides a unique means for model validation through comparison with actual recorded seismicity. Once it is established that the model is performing in a realistic manner, it can then be used to examine the micromechanics of cracking, failure and the associated seismicity and to help resolve the non-uniqueness of the geophysical interpretation. This is demonstrated by examining in detail the mechanics of one of the modelled seismic events by observation of the time dependence of the moment tensor and by direct examination of the particle motions at the simulated source. 相似文献
15.
3D geological models are created to integrate a set of input measurements into a single geological model. There are many problems with this approach, as there is uncertainty in all stages of the modelling process, from initial data collection to the approach used in the modelling scheme itself to calculate the geological model. This study looks at the uncertainty inherent in geological models due to data density and introduces a novel method to upscale geological data that optimises the information in the initial dataset. This method also provides the ability for the dominant trend of a geological dataset to be determined at different scales. By using self-organizing maps (SOM's) to examine the different metrics used to quantify a geological model, we allow for a larger range of metrics to be used compared to traditional statistical methods, due to the SOM's ability to deal with incomplete datasets. The classification of the models into clusters based on the geological metrics using k-means clustering provides a useful insight into the models that are most similar and models that are statistical outliers. Our approach is guided and can be calculated on any input dataset of this type to determine the effect that data density will have on a resultant model. These models are all statistical derivations that represent simplifications and different scales of the initial dataset and can be used to interrogate the scale of observations. 相似文献
16.
离散裂隙渗流方法与裂隙化渗透介质建模 总被引：4，自引：1，他引：4
流体渗流模拟的连续介质方法通常适用于多孔地质体，并不一定适用于裂隙岩体，由于裂隙分布及其特征与孔隙差异较大。若流体渗流主要受裂隙的控制，对于一定尺寸的裂隙岩体，多孔介质假设则较难刻划裂隙岩体的渗流特征。离散裂隙渗流方法不但可直接用于模拟裂隙岩体非均质性和各向异性等渗流特征，而且可用其确定所研究的裂隙岩体典型单元体及其水力传导（渗透）张量大小。主要讨论了以下问题：（1）饱和裂隙介质中一般的离散流体渗流模拟；（2）裂隙岩体中的REV（典型单元体）及其水力传导（渗透）张量的确定；（3）利用离散裂隙网络流体渗流模型研究裂隙方向几何参数对水力传导系数和REV的影响；（4）在二维和三维离散裂隙流体渗流模型中对区域大裂隙和局部小裂隙的处理方法。调查结果显示离散裂隙流体渗流数学模型可用来评价不同尺度上的裂隙岩体的水力特征，以及裂隙方向对裂隙化岩体的水力特征有着不可忽视的影响。同时，局部小裂隙、区域大裂隙应当区别对待，以便据其所起的作用及水力特征，建立裂隙化岩体相应的流体渗流模型。 相似文献
17.
碳同位素动力学模拟及其在天然气评价中的应用 总被引：2，自引：0，他引：2
天然气碳同位素动力学模拟是国际油气地球化学界的前沿性研究方向。它和盆地沉积埋藏史、受热史结合起来,对于评价天然气的成因和成藏历史是一种新而且有效的手段,正逐渐为人们所接受。介绍了天然气形成的碳同位素动力学模拟,以及其在评价天然气的成熟度、气源、运移-聚集史和油气比研究等方面应用的新进展,充分展示了其具有良好的应用价值。天然气碳同位素特征不仅受母源、成熟度的影响,而且与运聚条件、沉积盆地增温速率有关。瞬时聚集气与累积聚集气在碳同位素特征存在明显差别。碳同位素分馏动力学模型在不同含油气盆地会存在差异,不仅取决于气源条件,还与运移-聚集史、沉积-构造史有关。中国叠合型盆地天然气藏成因复杂,具有多期、多源的特点,本研究对这类天然气的研究与评价提供了新思路。 相似文献
18.
This paper presents robust algorithms for application in polyhedral modelling of rock mass structure based on discrete fracture networks. The algorithms improve the robustness of current polyhedral modellers to challenging or degenerate geometries and geometrical errors. These issues are inevitably encountered when the fracture network realisations incorporate large numbers of fractures, or regions of densely packed fractures are modelled, or when the number of fracture network realisations interrogated is large. Several stages in the polyhedral modelling process which are sensitive to geometrical errors are reviewed and algorithms which are robust and capable of handling topological errors in the input fracture network geometry are presented. 相似文献
19.
本文分别以非接触式测量与三维裂隙网络模拟技术对汶川县绵虒镇大溪沟沟口高陡斜坡的结构面系统进行了深入研究。以无人机、数字近景摄影测量与三维激光扫描方法建立了现场斜坡的三维DEM模型并识别与解译了斜坡的结构面系统。尤其是采用无人机与近景摄影测量技术,识别并解译了整体斜坡的长大控制性结构面与坡面上的6663条随机构造结构面。基于以上数据,本文提出了一种适用于高陡斜坡分析的超大窗口三维裂隙网络模拟方法,采用概率统计与空间几何推导的方法,建立了岩体三维结构面的直径、产状与密度计算方法。这种方法更加简便且针对性强,现场验证也表明其具有较高的模拟精度。 相似文献
20.
Judith Sausse Chrystel Dezayes Louis Dorbath Albert Genter Joachim Place 《Comptes Rendus Geoscience》2010,342(7-8):531-545
This study presents a new deterministic 3D model of the fracture zones observed in the granitic reservoir of the Soultz European geothermal project. The major fracture zones encountered around 6 wells (4550, EPS1, GPK1, GPK2, GPK3 and GPK4) consist in 53 main structures that are located and characterized in terms of size and orientation: 39 fracture zones, 8 microseismic structures and 6 structures derived from vertical seismic profiles are represented in the 3D model using Discrete Fracture Network tools of the gOcad modelling platform (Paradigm?, Earth Decision?). This work illustrates the complexity of 3D fracture zone correlation and interpretation in crystalline rock masses characterized at meter scale (borehole) and at the reservoir scale (kilometer) thanks to geophysical imaging techniques. 相似文献