NUMERICAL AND ANALYTICAL SOLUTIONS OF DISPERSION IN A FINITE,ADSORBING POROUS MEDIUM1

ABSTRACT Numerical and analytical solutions are developed for the distribution of a contaminant within an adsorbing porous medium in a unidirectional flow field subject to a step function for input concentration. The medium is considered to be homogeneous, isotropic, and areally finite. As a by-product, solutions are also obtained for the case of a non-absorbing porous medium. An example that demonstrates the applicability of the solutions is presented.     

Evaluation of Generic Types of Drilling Fluid Using a Risk-Based Analytic Hierarchy Process

The composition of drilling muds is based on a mixture of clays and additives in a base fluid. There are three generic categories of base fluid - water, oil, and synthetic. Water-based fluids (WBFs) are relatively environmentally benign, but drilling performance is better with oil-based fluids (OBFs). The oil and gas industry developed synthetic-based fluids (SBFs), such as vegetable esters, olefins, ethers, and others, which provide drilling performance comparable to OBFs, but with lower environmental and occupational health effects. The primary objective of this paper is to present a methodology to guide decision-making in the selection and evaluation of three generic types of drilling fluids using a risk-based analytic hierarchy process (AHP). In this paper a comparison of drilling fluids is made considering various activities involved in the life cycle of drilling fluids.This paper evaluates OBFs, WBFs, and SBFs based on four major impacts—operations, resources, economics, and liabilities. Four major activities—drilling, discharging offshore, loading and transporting, and disposing onshore—cause the operational impacts. Each activity involves risks related to occupational injuries (safety), general public health, environmental impact, and energy use. A multicriteria analysis strategy was used for the selection and evaluation of drilling fluids using a risk-based AHP. A four-level hierarchical structure is developed to determine the final relative scores, and the SBFs are found to be the best option.     

FIELD MEASUREMENT OF FLOW VELOCITIES,SUSPENDED SOLIDS CONCENTRATIONS,AND TEMPERATURES IN LAKE OKEECHOBEE1

ABSTRACT: This paper presents a field investigation of collecting hydrodynamic and sediment data in Lake Okeechobee with analyses examining mechanisms affecting sediment resuspension in the lake. Lake Okeechobee is a large subtropical lake located in south central Florida. Three‐dimensional flow velocities, suspended solids concentrations (SSC), and temperatures at four locations were measured from January 18 to March 5, 2000. Analyses of these data indicate that wind is the dominant factor in driving flow velocities and therefore transporting suspended solids. Wind direction also affects the SSC, especially in the north central and west littoral areas of the lake. The surface and bottom velocity components frequently flow in opposite directions, forming a stratification of the water column and preventing suspended solids from settling out. This retention of SSC in the water column may have a strong impact on the water quality of Lake Okeechobee. This study provides valuable storm event data and mechanism analyses, which will improve our understanding of the transport of suspended solids, thermal exchanges, and flow patterns within Lake Okeechobee.     

Intercomparison of Numerical Urban Dispersion Models – Part I: Street Canyon and Single Building Configurations

Microscale Computational Fluid Dynamics (CFD) models havebecome an efficient and common simulation tool forassessment and prediction of air quality in urban areas.The proper validation of such a model is a crucialprerequisite for its practical application. Within theframework of the European research network TRAPOS a workinggroup on computational fluid dynamics modelling wasestablished and model intercomparison exercises werelaunched. Different Computational Fluid Dynamics Codes wereapplied for simulating the wind flow and pollutantconcentration patterns in several test cases. The aim ofthe present model intercomparison is (1) to assess andallocate the source of differences that appear whendifferent CFD codes using the same turbulence model areapplied to well defined test cases and (2) to improve theknowledge base for model development and application.Throughout the series of model applications coveringmanifold urban configurations, the overall agreementbetween the various models and experimental data is fair.In spite of quantitative differences between the variousnumerical results, the models are capable of reproducingthe flow patterns and dispersion characteristics observedin urban areas but they show significant differences forthe turbulent kinetic energy field that controls thedispersion of pollutants.     

钻屑、钻井液固化处理及对环境的影响分析

钻屑和废钻井液的固化处理是现阶段钻井废物无害化处理的主要研究方向,研究利用固化剂对钻屑和废泥浆进行固化处理,优选配方(水泥+粉煤灰+添加剂)进行固化处理;同时考查了钻屑、钻井液固化填埋后对周围环境的影响。结果表明,固化物浸出液的分析结果符合国家危险废物鉴别标准(GB5085.3-1996)和国家污水综合排放标准(GB8978-1996),对周围环境水质调查监测,环境水质未受到污染,与填埋前的监测指标变化不大。     

化学氧化—混凝沉淀法处理油田作业废液

采用化学氧化—混凝沉淀法对油田作业废液进行处理,筛选出最佳的混凝条件及氧化条件。实验结果表明,与产出水混合处理后可使原水的悬浮物从500～1000 mg/L降至<3 mg/L、总铁<0.5 mg/L。处理后的污水由处理前的黑浆状变为清澈透明,淡黄色,基本达到了注水水质标准。该方法具有投资小、净化效果好、设备简单、占地面积小、操作方便、不产生二次污染等优点。     

石油加工与石油化工废料应用于钻井液

石油加工与石油化工废料，包括废白土、酸渣、碱渣、渣油、油泥、生产润滑油添加剂的废料、废催化剂、环烷酸釜残等，在钻井液中的用途较广，可以分别用作钻井液原始组分和润滑剂、消泡剂、多效防塌剂、抑制剂、稳定剂、废钻井液固化剂以及制备这些处理剂的基础材料。文中介绍了前苏联及独联体等在这方面的研究成果和现场应用情况。     

水平地震激励下储罐液体晃动分析

在考虑地基与储罐相互作用的情况下，采用有限元法对储罐在水平地震荷载作用下的液体晃动反应进行了分析。结果表明：罐内液体的晃动是长周期运动，并且是多阶振型的组合。从与小体积罐的比较可以看出，大型储液罐的液面晃动不只是以基本振型为主，前几阶振型对液面晃动的贡献也比较显著，并且液面晃动的基本周期比小体积罐的大很多。     

废油基钻井液处理及油回收技术研究

目前现场处理废油基钻井液一般采用集中填埋或回注地层方法,这不仅难以解决其污染问题,同时也浪费了其中所含有的大量柴油资源。通过大量的实验室和现场试验研究,使用“化学热洗-析油-离心”处理工艺,油回收率达到84%以上;研制开发出的清油剂-凝聚剂-絮凝剂化学热洗配方体系,适用于多种废油基钻井液的回收油处理,具有较好的工业推广应用前景。     

Sustainable oil-in-water analysis using a supercritical fluid carbon dioxide extraction system directly interfaced with infrared spectroscopy

A direct aqueous supercritical fluid extraction (SFE) system using carbon dioxide provides a sustainable means by which a vast range of industries may continue to depend on well established infrared (IR) techniques to determine oil-in-water. The SFE-IR method provides an environmentally friendly substitute for current national standard IR reference methods for measuring oil-in-water that rely on using increasingly restricted ozone depleting solvents whose manufacture is being phased out in accordance with international law. The SFE-IR analysis of a 500 mL water sample can be accomplished in 15 min. A rapid on-line SFE-IR calibration method has been implemented. With this calibration method, SFE-IR accuracy for determining diesel oil in 500 mL spiked water samples using single wave number measurement was 86.0%–98.8% with precision (RSD) ranging from 2.5%–7.0%. Using a general purpose calculation which involves measuring infrared absorbance values at three di erent wave numbers, SFE-IR method accuracy for determining diesel oil in 500 mL spiked water samples was 83.7%–92.2% with RSD 1.0%–9.3%. Data is presented that indicates current long established national standard IR reference methods involving three wave number calculations should be reviewed since, without careful consideration, the inclusion of calculated aromatic hydrocarbon species contributions to final oil-in-water concentration values may provide less accurate results.