Development of a linear predictive model for carbon dioxide sequestration in deep saline carbonate aquifers

CO₂ injection into deep saline aquifers is a preferred method for mitigating CO₂ emission. Although deep saline aquifers are found in many sedimentary basins and provide very large storage capacities, several numerical simulations are needed before injection to determine the storage capacity of an aquifer. Since numerical simulations are expensive and time-consuming, using a predictive model enables quick estimation of CO₂ storage capacity of a deep saline aquifer. In order to create a predictive model, the ranges of variables that affect the CO₂ storage capacity were determined from published literature data. Correlations found in literature were used for other important parameters such as pore volume compressibility and density of brine. Latin hypercube space filling design was used to construct 100 simulation cases prepared using CMG STARS. The simulation period covered a total of 300 years of CO₂ storage. By using a least-squares method, linear and nonlinear predictive models were developed to estimate CO₂ storage capacity of deep saline carbonate aquifers. Numerical dispersion effects were considered by decreasing the grid dimensions. It was observed that a dimensionless linear predictive model is better than the nonlinear. The sensitivity analyses showed that the most important parameter that affects CO₂ storage capacity is depth. Most of the (up to 90%) injected gas dissolved into the formation water and a negligible amount of CO₂ reacted with carbonate.     

Managed aquifer recharge in community water supply: the Finnish experience and some international comparisons

This paper analyzes the use of managed aquifer recharge (MAR) in community water supply in Finland and presents some international experiences for comparison. The framework of MAR consists of the natural environment and physical infrastructure, as well as socio-economic aspects, all of which are interrelated. Local conditions form the basis of an MAR system and to a large degree determine infiltration options and the most suitable methods. Finnish hydrogeology, climate and local conditions are highly comparable to those in Sweden but differ from those of other parts of Europe, Australia, the USA and Asia. This article provides a holistic view of MAR not only as a technical means of resource enhancement for water supply but also as an element interacting with the natural environment and society.     

The Mahomet Aquifer

Abstract

Emerging intrastate transboundary issues focus on use of the Mahomet aquifer, which underlies about fifteen counties and many other political entities in east-central Illinois. This sand and gravel aquifer in the lower part of the buried Mahomet Bedrock Valley ranges between four and fourteen miles wide and from about 50 to 200 feet thick. Much of the region's rural population, several large communities, and many small towns obtain water from the Mahomet aquifer, as do industrial, agricultural, and commercial users. Increased development of the Mahomet aquifer to meet growing demands for water has caused conflicts over real or perceived adverse effects. One result has been the creation of fifteen resource protection zones and twelve water authorities. For groundwater supplies, resource protection zones help municipalities protect water-supply wells from potential adverse impacts. Many resource protection zones overlap one another, however, so this situation could lead to disputes over use of the resource. The reason that several of the twelve water authorities were organized was to meet a challenge perceived from a demand to be placed on the aquifer, in other words, a potential for conflict of use. Complicating the situation is that some of the water authorities overlap the resource protection zones. This could lead to disputes not only about water use, but also over which jurisdiction has the authority to settle a dispute. The Mahomet Aquifer Consortium was recently organized by concerned people representing diverse groundwater interests at the local level, including the private sector, professional organizations, and various governmental units. The consortium brings together representatives of some groups that typically did not communicate with each other in the past. The consortium may provide a forum through which emerging transboundary issues pertaining to use of the Mahomet aquifer can be addressed. Because the consortium is a voluntary organization that relies on consensus building, the success it may achieve in resolving future conflicts over groundwater use from the Mahomet aquifer remains to be seen.     

Groundwater Exploitation and Its Impact on the Environment in the North China Plain

Abstract

The North China Plain (NCP) is one of China's most important social, economic, and agricultural regions. Currently, the Plain has 17,950 thousand ha of cultivated land, 71.1 percent of which is irrigated, consuming more than 70 percent of the total water supply. Increasing water demands associated with rapid urban and industrial development and expansion of irrigated land have led to overexploitation of both surface and the ratio of groundwater resources, particularly north of the Yellow River. In 1993, the ratio of groundwater exploitation to recharge in many parts of the NCP exceeded 1.0; in some areas, the ratio exceeded 1.5. Consequently, about 1.06 million ha of water-short irrigated areas in the NCP also have poor water quality. Persistent groundwater overexploitation in the northern parts of the NCP has resulted in water-level declines in both shallow and deep aquifers. According to data from 600 shallow groundwater observation wells in the Hebei Plain, the average depth to water increased from 7.23 m in 1983 to 11.52 m in 1993, indicating an average water-table decline of 0.425 m/year. Water table declines are not uniformly distributed throughout the area. Depletion rates are generally greatest beneath cities and intensively groundwater-irrigated areas. Water-table declines have also varied over time. With the continued decline of groundwater levels, large depression cones have formed both in unconfined and confined aquifers beneath the Hebei Plain. Groundwater depletion in the NCP has severely impacted the environment. Large tracts of land that overlie cones of depression have subsided, seawater has intruded into previously freshwater aquifers in coastal plains, and ground-water quality has deteriorated due to salinization, seawater intrusion, and untreated urban and industrial wastewater discharge. In order to balance groundwater exploitation with recharge, the major remedial measures suggested are to strengthen groundwater management, to raise water use efficiency, to adjust the water-consumed structure, and to increase water supply     

Computing Green's function of the initial-boundary value problem for the wave equation in a layered cylinder

A new analytical method for the approximate computation of the time-dependent Green's function for the initial-boundary value problem of the three-dimensional wave equation on multi-layered bounded cylinder is suggested in this paper. The method is based on the derivation of eigenvalues and eigenfunctions for an ordinary differential equation with piecewise constant coefficients, and an approximate computation of Green's function in the form of the Fourier series with a finite number of terms relative to the orthogonal set of the derived eigenfunctions. The computational experiment confirms the robustness of the method.     

绥化市平原区地下水系统分析

地下水系统的水资源分布与开发利用,受自然地理条件、含水层的空间结构、社会经济状况、产业结构布局、城市化进程等诸多因素的影响和制约,在不同的地下水系统中,这些因素的作用和影响程度都有明显的差异,因而,开展地下水系统分析,对地下水系统进行合理划分,确定不同层次地下水系统的区、级,是更准确评价地下水资源的基础,是进一步运用地下水系统理论进行地下水资源合理开发利用研究和正确认识地下水资源开发利用与环境保护之间的相互关系的前提。基于以上目的,论文运用地下水系统理论,对绥化市平原区地下水系统进行了具体分析。     

利用GM（1,1）模型对地下水恢复进行预测分析

沧州市区关停深层自备井后,深层地下水恢复取得了明显的效果。本文采用色系统中GM（1,1）模型对第Ⅴ含水组地下水埋深进行预测。     

浅海低频多层介质中声传播损失的数学模型

声场仿真是研究舰船声场和海洋声环境的重要手段，而声传播特性仿真是建立声场环境的关键一环。应用简正波理论并结合波数积分法，建立了浅海低频声传播特性的仿真数学模型。数值计算与资料实验数据表明，该仿真模型能较好地预报浅海低频声传播损失，具有计算精度高、计算速度快等优点。     

灰岩防治水的示踪试验方法研究

为探查潘北矿C3I组灰岩含水层与奥灰含水层之间的水力联系，以及F1，DFl断层的导、阻水性，用KI为示踪剂，开展示踪试验．结果表明，井田内奥灰水仅与C3 3下存在局部水力联系，与C3^1 C3^2灰岩含水层间无水力联系．在试验范围内，奥灰水通过不同尺度的通道对C3^3下含水层进行补给；露头灰岩区中F1，DF1均为导水断层，为A组煤层在开采过程中对底板灰岩水防治提供了科学依据．     

一维线形超声相控阵换能器辐射声场研究

在相控阵超声工业无损检测中,超声换能器的声场分布直接决定着被检测区域的回波信息特征,从而影响检测结果。本文通过研究超声波在固体介质中的传播规律,建立了超声相控阵换能器在介质中辐射声场的数学模型,数值模拟了在一层、两层介质中相控阵换能器的辐射声场图,声场结果为更形象直观的了解声场变化和检测结果评估提供理论依据。