井间地震数据的期望净现值

勘探与开发项目的经济效益与远景构造评价中所用地震资料的成本及价值密切相关。那么，如何评估地震资料的价值？这里介绍一种评价井间地震数据期望净现值的方法，该方法可在地震测量之前估算其期望净现值，以确定地震测量的经济价值。     

碳酸盐岩储层的构造控制热液蚀变

本期（2006年11期）《AAPG Bulletin》专辑的内容是碳酸盐岩及其储层的构造控制热液蚀变。这种蚀变涉及碳酸盐主岩的一系列岩相变化，包括硫化物矿床、热液白云岩和淋溶石灰岩，它在很多情况下都会对储层的类型、几何形态、性能和分布产生重大影响。在北美地区，热液白云岩（HTD）储层的勘探和开发已有很长历史，其最早的油气发现是在美国东北部的奥陶系莱马-印第安纳（Lima-Indiana）和其它构造带（Hurley和Budros，1990；Wickstrom等，1992），而目前在美国东北部和加拿大东部的密歇根盆地和阿巴拉契亚盆地北部的特伦顿-布莱克里弗（Trenton-BlackRiver）成藏层带及其他层位，仍继续有油气发现。     

4D地震项目的技术风险评价

介绍了一种评价４Ｄ地震项目技术风险的表格，利用这种表格可以快速，定量地评价４Ｄ项目的技术风险。     

智能井控制的优化

结合使用新的优化软件和商业油藏模拟软件，分别对采用和不采用智能油井控制装置完井的油藏产量进行了预测和优化。井下流量控制装置给非常规油井的生产带来了灵活性。利用它们可以单独控制多分支井的各个分支，从而实现石油产量最大化或对不需要的水或气产量最小化。文中通过案例介绍了一种智能井(即安装有井下传感器和流量控制器的油井)运行的优化方法。该方法需要把共轭梯度优化技术与包含一个详细的多井段油井模型的商业模拟软件结合使用。该综合优化技术用于解决涉及不同类型油井和地质模型，以及多次地质统计模拟结果(geostatistical realization)的问题。多个案例均说明，采用流量控制装置能够改善油井的预测生产动态，其中一个改善的程度高达65％。     

Preparation and storage stability of dried salted mutton

Minced (8 or 18 mm plate) mutton with salt (25%) and sorbate (0·4%) was pressed into cakes about 11 cm in diameter and 3 cm high. The cakes were partially dried in an air oven at 40°C for 48 h to a water activity of about 0·75. The cakes were packed, either in vacuo or in air, and stored at 30 or 2°C for up to 60 days. Objective assessment of quality showed that these dried salted meats can be kept for up to 60 days at 30°C with little loss of textural or nutritional quality although some fading, due to haemoprotein breakdown, occurs. Packaging in vacuum, however, minimises this loss of colour and would be recommended for centralised manufacture prior to distribution in developing, tropical countries.     

A new model for atmospheric oxygen over Phanerozoic time

A mathematical model has been constructed that enables calculation of the level of atmospheric O2 over the past 570 my from rates of burial and weathering of organic carbon (C) and pyrite sulfur (S). Burial rates as a function of time are calculated from an assumed constant worldwide clastic sedimentation rate and the relative abundance, and C and S contents, of the three rock types: marine sandstones and shales, coal basin sediments, and other non-marine clastics (red beds, arkoses). By our model, values of O2 versus time, using a constant total sedimentation rate, agree with those for variable sedimentation derived from present-day rock abundances and estimates of erosional losses since deposition. This agreement is the result of our reliance on the idea that any increase in total worldwide sediment burial, with consequently faster burial of C and S and greater O2 production, must be accompanied by a corresponding increase in erosion and increased exposure of C and S on the continents to O2 consumption via weathering. It is the redistribution of sediment between the three different rock types, and not total sedimentation rate, that is important in O2 control. To add stability to the system, negative feedback against excessive O2 fluctuation was provided in the modeling by the geologically reasonable assignment of higher weathering rates to younger rocks, resulting in rapid recycling of C and S. We did not use direct O2 negative feedback on either weathering of C and S or burial of C because weathering rates are assumed to be limited by uplift and erosion, and the burial rate of C limited by the rate of sediment deposition. The latter assumption is the result of modern sediment studies which show that marine organic matter burial occurs mainly in oxygenated shallow water and is limited by the rate of supply of nutrients to the oceans by rivers. Results of the modeling indicate that atmospheric O2 probably has varied appreciably over Phanerozoic time. During the Late Carboniferous and Permian periods O2 was higher than previously because of the rise of vascular land plants and the widespread burial of organic matter in vast coal swamps. A large decrease in O2 during the Late Permian was due probably to the drying-up of the coal swamps and deposition of a large proportion of total sediment in C and S-free continental red beds. Sensitivity study shows that major parameters affecting results are the mean C concentration in coal basins and the relative sizes of the reservoirs of young (rapidly recycled) versus old rocks. Less sensitivity was found for changes over time in total land area undergoing weathering and the use of direct O2 negative feedback on marine carbon burial. Good agreement for rates of C burial calculated via our model and via independent models, which are based on the use of stable carbon isotopes, indicates that the dominant factor that has brought about changes in atmospheric O2 level (and the isotopic composition of dissolved inorganic carbon in seawater) over Phanerozoic time is sedimentation and not weathering or higher temperature phenomena such as basalt-seawater reaction.