压裂充填技术的改进与应用

针对茨榆坨油田普通稠油油藏低压、低渗、出砂、油稠、地层染污严重等问题,结合茨13断块和茨9断块油藏特点,实施了压裂充填技术.通过运用端部脱砂原理,对携砂液、充填砂以及压裂参数进行优化和改进,实现了对低压、低渗稠油油藏的地层改造,对因出砂造成的近井亏空地带进行了高压充填,在近井地带形成了新的高渗透渗流通道,有效地改善了原油在井底的流动条件.现场应用情况表明,措施后油井增产效果显著,地层出砂得到有效地遏制,区块开发效果明显改善.     

Estimating the natural rate of interest in an open economy

The concept of the natural or equilibrium rate of interest has attracted a lot of attention from monetary policymakers in recent years. Most attempts to estimate the natural rate use a closed-economy framework. We argue that in the face of greater integration of global product and capital markets, an open economy framework is more appropriate. We provide some initial estimates of the natural rate for the USA and Japan in a two-country framework. Our identifying assumptions include a close relationship between the time-varying natural rate of interest and the low-frequency fluctuations of potential output growth in both the home country and the foreign country. Our results suggest that the natural rates in both countries are mainly determined by their own trend growth rates of potential output. Nevertheless, the other country’s trend growth plays an important role in several specific periods. The gap between the actual real interest rate and our estimated natural rate offers valuable insights into the recent stance of monetary policy in both of these two countries.     

Spatial-dynamic seawater intrusion and pumping cost externalities in a confined aquifer

This paper analytically develops the economic theory of seawater intrusion in confined aquifers and, in the process, creates generally applicable solution methods for illuminating steady-state spatial externality relationships for other spatial-dynamic diffusion resource management issues. By linking a confined aquifer and its unconfined recharge region with a dynamic boundary condition neglected in the economics literature, we introduce the physical realities that generate spatial externalities in all renewable confined aquifers. We derive spatial-dynamic first-order conditions for optimal extraction and characterize the policy relevant spatial-dynamic pumping cost and seawater intrusion cost externalities with hydrological assumptions appropriate to the different dynamic timescales of system components and the focus on seawater intrusion. For confined aquifers, we prove the marginal seawater intrusion cost externality decreases linearly in distance from the coast. Moreover, we demonstrate that the marginal seawater intrusion cost externality generally exceeds marginal pumping costs near the coast, implying substantial divergence between optimal and common property extraction near the coast, and significant divergence may extend to the inland aquifer boundary depending on both the magnitude and shape of the revenue function relative to extraction costs and aquifer parameters.     

Measuring resource scarcity in non-renewable resource with an application to oil and natural gas in Alberta

In this paper annual Canadian exploration data are used to estimate a multiple-output translog exploration cost function. A new definition of depletion is introduced and its estimated coefficient is found to be statistically significant. The fitted cost function parameters are then used to obtain estimates of the marginal costs of exploration for oil and gas. Our estimated marginal exploration costs are smaller than in previour studies because we have allowed for technical progress which offsets the depletion effects. These marginal cost estimates are employed, along with previous estimates of exploration rents, to measure resource scarcity. We find some evidence for the increased scarcity of oil and gas in Alberta. For oil there is a 10.1% per year increase in scarcity along the trend line while for natural gas there is a 2.4% per year increase in scarcity along the trend line.     

Effects of instantaneous groundwater availability on irrigated agriculture and implications for aquifer management

Groundwater is an important input for agricultural production in many parts of the world. Aquifer depletion has been shown to affect the rate that groundwater can be extracted from an aquifer. In this paper, we develop an analytical framework that accounts explicitly for the effects of limited instantaneous groundwater extraction rate (well capacity) on a producer's irrigation decisions. We show that limited well capacities can affect the producer’s groundwater use and profit. We draw three important insights from these findings. First, we demonstrate that the price elasticity of demand for groundwater is higher for lower well capacities. Second, farmers’ irrigation decisions are non-monotonic with respect to well capacity and climate conditions. Under a drier climate, producers with greater well capacities increase their groundwater use, and producers with lower well capacities reduce their water use. Third, through numerical analysis, we show that considering spatial heterogeneity in well capacities is important for estimating the cost-effectiveness and distributional impacts of groundwater management policies. Our results shed new light on the importance of extraction capacity for groundwater management policies and the potential impacts of climate change on agricultural production.     

Price clustering and natural resistance points in the Dutch stock market: A natural experiment

This paper focuses on the tendency of stock prices to cluster at round numbers (like 10, 20, 30, etc. and to a lesser extent 5, 15, 25, etc.) and the related effect of round number price barriers (prices pass round numbers less frequently than other numbers). Two competing hypotheses are tested, using data from the Dutch stock market of the period 1990–2001. After 1 January 1999 stock prices were listed in euros, while guilders were still the currency of daily life until 2002. The aspiration level hypothesis predicts that round number effects in guilders will only slowly disappear. The odd price hypothesis predicts an abrupt change in round number effects after 1 January 1999. Generally, the results are consistent with the odd price hypothesis.     

Instabilities and robust control in natural resource management

Most renewable natural resources exhibit marked demographic and environmental stochasticities, which are exarcebated in management decisions by the uncertainty regarding the choice of an appropriate model to describe system dynamics. Moreover, demand and supply analysis often indicates the presence of instabilities and multiple equilibria, which may lead to management problems that are intensified by uncertainty on the evolution of the resource stock. In this paper the fishery management problem is used as an example to explore the potential of robust optimal control, where the objective is to choose a harvesting rule that will work under a range of admissible specifications for the stock-recruitment equation. The paper derives robust harvesting rules leading to a unique equilibrium, which could be helpful in the design of policy instruments such as robust quota systems.

     

Economic natural selection in Bertrand and Cournot settings

We study economic natural selection in classical oligopoly settings. When underlying pure strategies consist of a finite number of prices, convex monotonic dynamics always converge under a weak condition to the smallest price in the support of the initial state that exceeds marginal cost. When underlying pure strategies consist of a finite number of quantities, monotonic dynamics always converge under a specific condition to a quantity equal or similar to classical Cournot equilibrium.     

Productivity growth in natural resource industries and the environment: an application to the Korean tuna purse-seine fleet in the Pacific Ocean

Measures of multifactor productivity growth in natural resource industries are misleading without accounting for the effects on the environment. This paper introduces environmental effects into an output-oriented Malmquist index of multifactor productivity growth in order to evaluate growth in productivity and technical efficiency for Korean purse seine vessels fishing for tuna in the Western and Central Pacific Ocean.     

Government investment in natural capital

This paper presents a new approach to the measurement of natural capital. A distinguishing feature of this approach is the use of investment criteria that are consistent with the main features of physical capital, thus maintaining consistency in the measurement of different types of capital. This new approach was applied to the expenditures of the federal government in Canada as recorded in the Public Accounts for fiscal year 2004-05. My results indicate that, in 2004-05, total investment in natural capital by the federal government amounted to 2.6% of net budgetary expenditures. Spending on physical capital, the only component that is currently included as investment in the National Accounts, represented only 5% of total investment in natural capital.     

Immigration and the natural rate of unemployment in Australia

This paper presents an indirect test of the proposition that a decrease in the rate of immigration into Australia during the early 1960s lowered the efficiency with which unemployed persons and unfilled job vacancies were matched, and increased labor turnover, thereby increasing the “natural” rate of unemployment. A theoretical model of employment growth is used to derive an expression for the steady-state relationship between unemployment and vacancies. Estimates of the model are obtained for the period 1955i–1973ii during which distinctly different immigration levels occurred. The empirical results are not consistent with the contention that a decrease in immigration caused the relationship between unemployment and job vacancies in Australia to shift outward. Therefore, the evidence suggests that the unemployment rate associated with a given level of labor demand was not significantly increased by the reduction in immigration to Australia.     

A complete characterization of optimal growth paths in an aggregated model with a non-concave production function

We use the Principle of Optimality in addition to the Euler equation in order to provide a characterization of optimal one-sector growth for all ranges of interest rates when the technology is not convex. Our key result is that the sequence of capital stocks is necessarily monotonic. For certain interest rates we show that the optimal path converges to a steady state only if the initial capital stock is above a critical level, otherwise it converges to zero. Finally, we demonstrate that the set of points for which the value function is differentiable is precisely the set of initial capital stocks from which there is a unique optimal path.     

Identification of development indicators in tropical mountainous regions and some implications for natural resource policy designs: an integrated community case study

In tropical and subtropical countries a social gradient can be observed in mountainous regions between small-scale farmers on fragile ecosystems associated with human poverty, and the fertile plains and broad valleys with large-scale cash crop productions and industrial centers associated with relative economic welfare. Sustainable community development paths have to be identified in these less privileged regions. The objective of this study was to make a contribution for defining and assessing development indicators at community level, including ecological, economic and social dimensions, to elicit the conflicting objectives in development and to discuss some practical implications. The study was performed in a typical watershed in central Honduras and special attention was given to autochthonous and qualitative indicators for development. Using the pressure-state-response model as a framework, a series of indicators were identified and assessed, which were also used by the local population and grouped into landscape structure, soil fertility, water availability and quality, production system and extractive activities, economic and social performance, and institutions. The development path in this specific case illustrated the transition from an expansive forest conversion agriculture to an intensified and diversified agriculture. This was made possible through technology transfer and improved market access. However, this development path, while increasing economic welfare, generated increasing negative environmental impacts caused by pesticide residues, soil erosion and less regular water supply. As the watershed carrying capacity for traditional shifting cultivation (used as a system indicator) reached its ecological limit, new sustainable development strategies had to be identified. The implications of the study for policy design are that tools need to be provided for natural and environmental resource monitoring, which may consist of sustainability goal definitions, a minimal set of indicators and simple maps for planning land use at local level.     

Demographic pressure and natural resources conservation

A field survey was carried out in the villages of Nlobesse'e at the Western periphery of the Dja Biosphere Reserve, South Cameroon, to evaluate the various effects that the increase in the local populations exert on the conservation of the natural resources of the reserve. Survey results show that the population was increasing rapidly at 40.00/00 per annum, with 61.54% of the total inhabitants originating from other parts of the country. Despite the rapid population growth, the population of the Kaka and Baka ethnic groups also known as the pigmies who have been noted by ECOFAC (Ecosystème Forestière d'Afrique Centrale) for having a marked negative impact on the conservation of the natural resources (because they depend mostly on the natural resources of the reserve for their livelihood and practice very little or no agriculture) were decreasing at a rate of 6.2%. Probably they sought better hunting, gathering and collecting conditions elsewhere in the reserve. Animal proteins originating from the reserve provide most of the animal proteins consumed by the households and the entire population of Nlobesse'e demands 44.4 kg of “bush meat” per day. It was also noted that the local population practiced very little agriculture in the reserve. Hunting and fishing, activities that have been noted for having a negative influence on the conservation of biodiversity contributed 15.2% and 11.2%, respectively, of the total income of the households. Other sources of income included: wages earned from the agro-plantation that contributed 40.3%, farming 24.2%, commerce 3% and others 4.58%. Merchant middlemen also referred to as “buyam sellam” and individuals with no commercial interest were the two main relay agents responsible for transporting natural resources out of Nlobesse'e. It would have been expected that the increasing population combined to the high incidence of poverty in the region (per capita income of 225 FCFA or $0.3 per day) would have exerted a high sustainability pressure on the conservation of reserve resources. However, this was not the case because of an agro-plantation in the area that provided the local population with the necessary income to buy foodstuff and other needed resources from far away areas. To maintain this trend, it is recommended that other sources of income such as the creation of small-scale enterprises and ecotourism should be encouraged in and around biospheres reserves.     

Spatially optimal habitat management for enhancing natural control of an invasive agricultural pest: Soybean aphid

By their direct effects on private profitability, invasive agricultural pests create special incentives for management that set them apart from other categories of invasive species. One attractive nonchemical management approach for agricultural pests relies upon biological control by natural enemies. By improving the habitat of natural enemies of invasive agricultural pests, biological pest control can become privately attractive. This study develops a spatial optimization model to explore economically optimal spatial configuration of natural enemy habitat in agricultural landscapes. The model is applied to the management of soybean aphid (Aphis glycines), a recent invasive pest species of soybean production systems in the North Central region of the United States. Results indicate that non-crop habitat management can be a promising pest management option for organic cropping systems. Under current prices, however, habitat management tends to reduce net returns for conventional farms. Both area and configuration of non-crop habitats affect economic performance, with the greatest value coming from small, scattered areas of habitat.