Numerical experiments for the conductive properties of saturated rock

The reservoir evaluation as a key technology in oil exploration and production is based on the electrical transport property (ETP) of saturated rock that is described in a mathematical form with Arhcie’s equa-tion. But there have been increasing cases observed in many researches indicating that the ETP is non-Archie especially for the complex reservoir with low porosity and permeability. In this paper,the numerical experiments based on the Lattice Boltzmann method (LBM) have been employed to study the effect of porous structure and fluids on the ETP for revealing the nature of non-Archie phenomenon in micro-scale. The results of numerical experiments have proved that the saturation exponent n is a function of water saturation and porosity instead of being a constant in Archie’s equation. And then,a new formula has been developed for the EPT through combining the result of numerical simulation with that of laboratory measurements. The calculations from the new formula show very good agreement with laboratory measurements to demonstrate the efficiency of the new formula over the conventional methods in non-Archie rock.     

A positive definite continuous FEM model for advection

This work introduces a continuous and sign-preserving finite element model (FEM) for advection problems. The model is formulated by integrating flux corrected transport technique (FCT) with the characteristic based (CB) FEM. Low order solution for the FCT has the form of element contribution and derives from an upwind monotone scheme with the minimum necessary diffusion for positivity. Selected numerical experiments illustrate the efficacy of the method by comparing results with some successful models, by demonstrating an approximate conservation of the accuracy of original CB algorithm once the complete procedure is operating, and by testing the model for severe time dependent advective flows.     

Thermal conductive heating in fractured bedrock: Screening calculations to assess the effect of groundwater influx

A two-dimensional semi-analytical heat transfer solution is developed and a parameter sensitivity analysis performed to determine the relative importance of rock material properties (density, thermal conductivity and heat capacity) and hydrogeological properties (hydraulic gradient, fracture aperture, fracture spacing) on the ability to heat fractured rock using thermal conductive heating (TCH). The solution is developed using a Green’s function approach in which an integral equation is constructed for the temperature in the fracture. Subsurface temperature distributions are far more sensitive to hydrogeological properties than material properties. The bulk ground water influx (q) can provide a good estimate of the extent of influx cooling when influx is low to moderate, allowing the prediction of temperatures during heating without specific knowledge of the aperture and spacing of fractures. Target temperatures may not be reached or may be significantly delayed when the groundwater influx is large.     

Legacies from three former manufactured-gas plants: impacts on groundwater quality

Groundwater contamination due to accidental releases of mono- and polycyclic aromatic compounds (MAHs and PAHs) from decommissioned manufactured-gas plants is an ongoing and litigious problem. The MAHs and PAHs are derived from coal tar, which was a by-product of the gas-manufacturing process. While originally designed to contain coal tar, the manufactured-gas plant structures that remain today have often degraded over time and are not completely leak-proof. Over a period of many years, subsurface water has seeped into and out of the structures, resulting in groundwater contamination. This was particularly true once the tops of the structures were removed. In this study, process-based simulations were conducted to estimate the groundwater-quality impacts of accidental releases of dissolved naphthalene (C₁₀H₈) from the sites of three former manufactured-gas plants. The results from one-dimensional, transient, unsaturated, near-surface fluid-flow and solute-transport simulations served as input to three-dimensional saturated subsurface fluid-flow and solute-transport simulations. The simulation results and sensitivity analysis reported here indicate that accidental releases of naphthalene had significant, negative impacts on groundwater quality at each of the three sites. Electronic Publication     

论北半球三大温带草原农垦与沙漠化的关系

我国东北西部和内蒙中东部,与北哈萨克斯坦、美国中西部大平原为北半球温带三大肥沃草原。雨量在300~ 400mm之间,地形平坦,气候适宜于畜牧业,实为天然的殷实草原。文章根据调查材料和文献提供了有关这三大草场大规模农垦旱作以致变成沙荒、沙漠化土地和尘源的一些信息。     

Tidal Vorticity around a Coastal Promontory

The vorticity generation around a coastal promontory is examined using a transport vorticity equation. The complete vorticity balance analysis is made for the transient and residual vorticity generations around an idealized, symmetric promontory. The topographic vorticity tendency is found to be the dominant forcing term in the production of transient tidal vorticities. This result is different from the previous works which emphasized the effects of lateral and bottom frictions. The residual vorticity balance is between advection and topographic vorticity tendency. The model results are consistent with the observations off Gay Head, Massachusetts. Also, the stability of a promontory as well as the offshore sand bank formation are studied by examining the sand transport pattern around the promontory. Strong deposition occurs off the tip of the promontory while erosion occurs along the upstream slope of the promontory suggesting that an originally symmetric promontory tends to incline cyclonically from the axis normal to the tidal stream. Such tendency is indeed found among coastal promontories.     

应用激电法勘查隐蔽型油砂矿--以二连盆地包楞油砂矿为例

巴音都兰凹陷包楞地区是二连盆地油砂资源主要分布的三大地区之一,油砂层厚度大、埋藏浅、含油率高,属于隐蔽型油砂矿,为古油藏破坏型成矿模式。为了进一步搞清油砂矿的分布范围和资源规模,对包楞油砂矿进行了激电法勘探,建立了电性参数与油砂矿分布之间的对应关系,圈定了油砂分布面积,预测了油砂地质资源,并选择激电法勘查的有利区进行了钻井验证。结果表明,激电法对包楞隐蔽油砂矿勘探是有效的勘查方法。     

Back‐barrier flooding by storm surges and overland flow

Low‐elevation areas within a sandy barrier island are subject to flooding via saturation overland flow following moderate storm surges and rainfall events. Using a high resolution topographic survey and simple hydrology models, we estimate the discharge and velocities from storm surge return flow and saturation overland flow. Results show that return flow velocities are of the same magnitude as the critical velocity necessary to mobilize sand when a hydraulic connection between the watershed and back‐barrier bay is present. Storms of moderate strength and rainfall intensity may be sufficient to keep the return channels open within the back‐barrier, thus providing natural conduits for water exchange from overwash events during extreme storm surges triggered by hurricanes. Copyright © 2011 John Wiley & Sons, Ltd.     

X-Ray Line Transfer in Plasmas with Large Velocity Gradients

An astrophysically relevant experiment is compared to the output of a multidimensional radiation transfer code in which populations and radiation are self-consistently treated. Experimental Al Ly α spectra obtained with a very high-resolution spectrometer are presented as quantitative evidence of dot plasma non-planar expansion. Analysis of these spectra using the code is performed, in particular examining the effects of velocity gradients in directions other than that of the primary expansion. These calculations are found to be in good agreement with the experimental results. Usage of the Ly α doublet as a planarity diagnostic is discussed.