基于正演模拟的复合曲流带砂体内部构型解剖研究及应用

Q油田是渤海大型河流相沉积的稠油油田,其北区NmⅣ1主力含油砂体为复合曲流带沉积,经过16年的注水开发,油水关系复杂,平面注水受效不均的问题日益严重,如何优化注釆结构来改善开发效果已成为急需解决的问题。优化现有注釆井网的关键是认识复合曲流带砂体内部不同单河道砂体的切叠关系及展布特征,即对目标砂体开展内部不同单河道的构型单元分布特征研究。首先,依据岩电标定的测井曲线特征、局部发育的薄夹层以及曲流河纵向下切模式,对复合砂体内部不同单河道砂进行划分与对比;然后基于单井沉积微相划分结果,开展井间剖面相对比分析,表明复合砂体内部存在5种不同单河道砂体切叠模式;建立5种正演概念模型,利用地震正演模拟合成地震记录,总结了不同单河道砂体间顶面高程差异、点坝边界、废弃河道等曲流河砂体构型边界的波形特征;利用地震属性提取及多种地质构型方法,综合分析,最终实现了海上大井距条件下复合曲流带砂体内部不同单一曲流河砂体构型边界的精细识别;最后由注采动态资料的响应关系评估不同的切叠模式对注水效果的侧向遮挡程度,并以此为依据,优化现有的注釆井网并取得了非常好的生产效果。     

Modelling controls on aeolian dune‐field pattern evolution

A second‐generation, source‐to‐sink cellular automaton‐based model presented here captures and quantifies many of the factors controlling the evolution of aeolian dune‐field patterns by varying only a small number of parameters. The role of sediment supply, sediment availability and transport capacity (together defined as sediment state) in the development and evolution of an aeolian dune‐field pattern over long time scales is quantified from model simulations. Seven dune‐field patterns can be classified from simulation results varying the sediment supply and transport capacity that control the type and frequency of dune interactions, the sediment availability of the system and, ultimately, the development of dune‐field patterns. This model allows predictions to be made about the range of sediment supply and wind strengths required to produce the dune‐field patterns seen in the real world. A new clustered dune‐field pattern is identified from model results and used to propose an alternative mechanism for the formation of superimposed dunes. Bedforms are hypothesized to cluster together, simultaneously forming two spatial scales of bedforms without first developing a large basal dune with small superimposed dunes. Manipulation of boundary conditions produces evolving dune fields with different spatial configurations of sediment supply. Trends of spacing and crest length increase with decreasing variability as the dune field matures. This simple model is a valuable tool which can be used to elucidate the dominant control of aeolian sediment state on the construction and evolution of aeolian dune‐field patterns.     

Estimation of irrigation return flow on monthly time resolution using SWAT model under limited data availability

ABSTRACT

This study is an assessment of the return flow ratio of an irrigation abstraction using the flow records of a downstream stream-gauging station, with the example of the Kozluk scheme irrigated by diverted water from Garzan Creek flowing through the southeastern region of Turkey. In the planning reports of the major dam projects of the region, an unverified return ratio was assumed in eliminating the influence of this irrigation on the flow measurements of Garzan Creek. The correctness of this assumed return ratio is evaluated by analysing the monthly streamflow measurements of the Besiri station through a Soil and Water Assessment Tool (SWAT) model constructed with the coarse-scale topography, land use and soil data from open source databases. The results show the necessity of irrigation project-based return flow analyses using regional fine-scale datasets, instead of rule-of-thumb assumptions, to determine the effects of irrigation activities on flow regimes more accurately.     

图形化的地学耦合建模环境与原型系统设计

耦合建模是近年来地学研究使用的重要方法.建模框架是应用较多的一类地学耦合建模环境.由于要求研究者完成耦合模型的程序编码,在一定程度上降低了它的可用性,同时也带给使用者更多的负担.本文以建模框架ESMF作为基础,对构建完全图形化的地学耦合建模环境中的问题和解决方法进行探讨.主要包括:根据确定的耦合模式及其隐含的模型调用和...     

A way to synchronize models with seismic faults for earthquake forecasting: Insights from a simple stochastic model

Numerical models are starting to be used for determining the future behaviour of seismic faults and fault networks. Their final goal would be to forecast future large earthquakes. In order to use them for this task, it is necessary to synchronize each model with the current status of the actual fault or fault network it simulates (just as, for example, meteorologists synchronize their models with the atmosphere by incorporating current atmospheric data in them). However, lithospheric dynamics is largely unobservable: important parameters cannot (or can rarely) be measured in Nature. Earthquakes, though, provide indirect but measurable clues of the stress and strain status in the lithosphere, which should be helpful for the synchronization of the models.The rupture area is one of the measurable parameters of earthquakes. Here we explore how it can be used to at least synchronize fault models between themselves and forecast synthetic earthquakes. Our purpose here is to forecast synthetic earthquakes in a simple but stochastic (random) fault model. By imposing the rupture area of the synthetic earthquakes of this model on other models, the latter become partially synchronized with the first one. We use these partially synchronized models to successfully forecast most of the largest earthquakes generated by the first model. This forecasting strategy outperforms others that only take into account the earthquake series. Our results suggest that probably a good way to synchronize more detailed models with real faults is to force them to reproduce the sequence of previous earthquake ruptures on the faults. This hypothesis could be tested in the future with more detailed models and actual seismic data.     

龙门山冲断带的隆升和川西前陆盆地的沉降

通过龙门山区和川西前陆盆地岩石样品的裂变径迹和镜质体反射率的测定和计算机模拟得出：１）松潘－甘孜褶皱带１０Ｍａ以来至少隆升了３－４ｋｍ，隆升速率最低为０．３－０．４ｍｍ／ａ；（２）龙门山逆冲推覆构造带１０Ｍａ以来至少隆升了５－６ｋｍ，隆升速率最低为０．０１６－０．０３２ｍｍ／ａ；（４）川西前陆盆地６０Ｍａ以来降升１－２ｋｍ，降升速率为０．０２８－０．０５ｍｍ／ａ；（５）１０Ｍａ以来北川－映秀－小关     

Water and salt balance modelling to predict the effects of land-use changes in forested catchments. 1. Small catchment water balance model

A long-term water balance model has been developed to predict the hydrological effects of land-use change (especially forest clearing) in small experimental catchments in the south-west of Western Australia. This small catchment model has been used as the building block for the development of a large catchment-scale model, and has also formed the basis for a coupled water and salt balance model, developed to predict the changes in stream salinity resulting from land-use and climate change. The application of the coupled salt and water balance model to predict stream salinities in two small experimental catchments, and the application of the large catchment-scale model to predict changes in water yield in a medium-sized catchment that is being mined for bauxite, are presented in Parts 2 and 3, respectively, of this series of papers. The small catchment model has been designed as a simple, robust, conceptually based model of the basic daily water balance fluxes in forested catchments. The responses of the catchment to rainfall and pan evaporation are conceptualized in terms of three interdependent subsurface stores A, B and F. Store A depicts a near-stream perched aquifer system; B represents a deeper, permanent groundwater system; and F is an intermediate, unsaturated infiltration store. The responses of these stores are characterized by a set of constitutive relations which involves a number of conceptual parameters. These parameters are estimated by calibration by comparing observed and predicted runoff. The model has performed very well in simulations carried out on Salmon and Wights, two small experimental catchments in the Collie River basin in south-west Western Australia. The results from the application of the model to these small catchments are presented in this paper.     

A sediment fluxes investigation for the 2-D modelling of large river morphodynamics

A complete understanding of alluvial-bed dynamics is desirable for evaluating a variety of issues related to water resources.Sediment fluxes were investigated in a bifurcation of the large Parana River near Rosario, Argentina. The backscatter estimations from the Doppler profilers provided the suspended load of the sediment forming the riverbed. An echo-sounder was applied to track the dunes yielding the bed-load estimation.Aiming to show the usefulness of the recorded data, a 2-D numerical code was applied to the 10-km long and 2-km wide Rosario reach. The morphodynamic module was un-coupled from the hydrodynamics assessment, which enabled the long-term prediction of the river morphology accounting for the hydrological yearly variation with a quasi-steady approach.Numerical experiments were performed to test the sensitivity of the hydrodynamic model to the computational time-step and mesh size, to test the un-coupling scheme performance regarding the full-dynamic modelling, to test the accuracy of the sediment transport formulae based on the field evidence and, finally, to provide guidance to properly fix the model parameters.     

New basis for the constitutive modelling of aggregated soils

Natural and compacted soils are usually characterized by aggregation of particles. The mechanical behaviour of these materials depends on soil structure. The oedometric compression tests performed on aggregated samples presented here showed that these materials exhibit a yield limit depending not only on stress history and stress state but also on soil structure. Evidence is provided using the neutron tomography technique. These results revealed that soil structure modification occurs together with plastic deformations. The experimental results are used to propose a new state parameter to quantify the soil structure. Based on pore-scale experimental observations, an evolution law for this parameter is proposed as a function of associated plastic strains. Considering both soil fabric and inter-particle bonding effects, a new yield limit depending on stress state, stress history and soil structure is introduced for the aggregated soils. Accordingly, a new constitutive framework consistent with strain hardening plasticity is proposed to consider soil structure effects in the modelling of aggregated soils.