美国著名地质学家ALISTAIR R. BROWN（《三维地震资料解释》作者）最近在AAPG撰文，详细介绍什么是地震资料的解释（What Is Seismic Interpretation?）。该文章短小精悍，希望你读了能解开心中的种种疑惑！ The horizon track on Lines 57 and 60 defining the structure, and the Horizon Slice sliced through the data volume 40ms below. (From Interpretation of Three-Dimensional Seismic Data, AAPG Memoir 42, SEG Investigations in Geophysics No. 9, Seventh Edition, 2011.) Seismic Interpretation is the extraction of subsurface geologic information from seismic data. On that definition we all are agreed.However, if we seek a more penetrating explanation, we find practitioners get tongue-tied and talk around the subject in a variety of ways.In this article I attempt to give a longer, more descriptive definition that will apply to every interpretation project involving reflection seismic data.The danger in seismic interpretation is in thinking that everything we see is geology! Reflection seismic data comprise: Continuity of reflections indicating geologic structure. Variability of reflections indicating stratigraphy, fluids and reservoir fabric. The seismic wavelet. Noise of various kinds and data defects. Seismic interpretation is the thoughtful procedure of separating these effects. The seismic wavelet starts as the pulse of seismic energy, which, generated by the energy source, travels down through the earth, is reflected and travels back up to the surface receivers carrying the geological information with it. This recorded wavelet is minimum phase of some frequency bandwidth, and during data processing it is converted (we hope) into a zero-phase wavelet, making interpretation easier and more accurate. The interpreter is not directly interested in the wavelet itself but rather in the geological information that it carries. Thus, understanding the wavelet and distinguishing its characteristics from details of the geology is one of the critical tasks of today’s interpreter. Noise is ever-present in seismic data. It may be random noise, it may be multiple reflections, it may be refracted energy, it may be other energy of unknown source. The data may suffer defects because of: Irregular data acquisition showing as footprint. Obstacles to the data acquisition crew. Equipment difficulties in the field. Processing problems. The interpreter must know enough about the acquisition and processing to recognize these undesirable features, and thus to not confuse them with the geology he/she seeks. Seismic energy is reflected from interfaces where the acoustic properties of the rocks change. These interfaces follow sedimentary boundaries created at the time of deposition of the sediments. Following the continuity of these reflections then defines for us the structure imposed on these boundaries by the tectonic forces of geologic history. Following this continuity and making structure maps is thus the most basic, and most traditional, activity of seismic interpretation. To aid in this endeavor the seismic interpreter can manipulate the data and the display in various ways. The time-honored approach to prepare the data for structural interpretation is to apply AGC (Automatic Gain Control) in the late stages of data processing. This reduces amplitude variability (where most of the statigraphic information lies), and hence increases visible data continuity. The interpreter also may compress the display color bar to optically saturate and thus to render invisible more of the amplitude variations. Other techniques include the use of Instantaneous Phase (which completely destroys amplitude information) and Structurally Oriented Filtering. All these are good ideas – provided the interpreter realizes that they are directed at structural interpretation only, and that the requirements of later, more advanced types of seismic interpretation are quite different. Once the structure has been established, the interpreter turns his attention to stratigraphic interpretation and the detection of hydrocarbon fluids. Overwhelming important here is seismic amplitude – and the amplitude may be presented to the interpreter or extracted from the data in various ways. The data loaded to the workstation must be True Amplitude and Zero Phase, and the interpreter must satisfy himself that the data used are such. Understanding the wavelet is complicated and very important (part of the fundamental separation of effects) but outside the scope of this article. In order to increase the visibility of stratigraphic variations the interpreter will remove the structure – and the best way to do this is to make a Horizon Slice. The concept behind the Horizon Slice is the reconstitution of a depositional surface at a key point in geologic history. The structure used for the reconstitution is most commonly defined at the level of the objective. However, it is often better to define the structure at one level (conformable with the objective) and to use this to remove the structure at the objective level. This very effectively separates structure into step one and stratigraphy into step two. This procedure is illustrated in the accompanying figure. The horizon tracked on the two vertical sections follows a reflection with good structural continuity and little, if any, stratigraphic variability. The horizon track is then displaced downwards by 40 ms (a simple horizon computation on the workstation) to intersect the prominent red blob visible below it, and the amplitude is then extracted along the displaced track. The resulting Horizon Slice, on the right of the figure, shows a very clear channel (the spatial pattern of the red blob) with interesting amplitude variations along it. When the seismic interpreter extends his analysis even further and enters the field of reservoir evaluation, the data requirements are even more stringent, but the Horizon Slice concept is still effective in removing the effects of structure. Some form of Inversion may be used here, and this process converts interface information (amplitude) into interval information (acoustic Impedance). The more advanced forms of inversion seek to remove the wavelet, and this is therefore part of the fundamental idea of separating effects. However, the challenge here is to exactly understand the wavelet that has to be removed. This is difficult, and many inversions suffer and projects fail because of this issue. So seismic interpretation is the thoughtful separation (with workstation assistance) of the various effects that the subsurface and the seismic acquisition process have mixed together! http://www.aapg.org/explorer/2013/05may/geocorner0513.cfm
再谈布朗先生与中国的计划生育政策 曾纪晴 前几天与武夷山老师就他所写书评中关于布朗先生坚决支持中国的计划生育政策顶了一下牛，抬了一下杠（参见： 与武夷山老师商榷 布朗先生与中国的计划生育政策 ）。我主要的观点是：假如布朗先生真的坚决支持中国的计划生育政策，那么他就不是一个真正的学者。武老师认为，布朗先生是不是真正的学者，读了他的著作才能下判断。不了解一个人的思想是无法对他下判断的。 由于我确实没有读过布朗先生的著作，所以我只能承认我的无知。但仅就布朗先生与中国计划生育政策这一点来说，依据武老师的介绍，我想还是可以做一个判断或推断的。但毕竟没有读人家的著作，对人家的思想不了解，说话的底气就不足。 刚好前天科学网送了一张 20 元的礼品卡，我立即就用它购买了布朗先生的《 B 模式 4.0 》。很快，今天我就收到书了。中午书一到手，午饭都来不及吃呢，就快速扫描书中有关人口与计划生育有关的所有内容。遗憾的是，布朗的书中没有出现坚决支持中国的计划生育政策那样的内容。我认真地读了《 B 模式 4.0 》第七章消除贫困，稳定人口，也没有关于中国计划生育的内容。仅在第七章第二段提到了一下中国在消除贫困人口方面取得了很大成功。之后，则大篇幅地介绍了除中国之外的其它国家成功的 family planning 方面的经验和成绩。布朗介绍了印度、巴西、几个东南亚国家（包括泰国、越南和印度尼西亚）、孟加拉国、非洲的一些国家（比如埃塞俄比亚）、伊朗和墨西哥等国家实 行 family plan 的情况，着重推介了除印度之外的那些成功推行 family plan 国家的有关降低和稳定人口数量的成功经验。所有那些推行 family plan 的国家，都根本没有中国计划生育的影子。 按理，假如布朗先生坚决支持中国的计划生育政策，在 《 B 模式 4.0 》第七章消除贫困，稳定人口他就应该好好介绍一下中国计划生育的成功经验啊。但是，布朗先生根本就没有介绍中国的计划生育。我想，他应该是知道这样一个事实：中国的计划生育政策是完全不可能向世界其它国家推广的，介绍它就没有任何的意义。而世界其它国家成功的 family planning 则是完全可以向世界推广的，也就是具有普遍的意义和价值。 假如布朗先生不了解中国的计划生育政策，作为一个关注资源环境与人口问题的著名人士，那是不可想象的。布朗先生应该是知道中国的计划生育政策是不同于 family planning 的。所以，他介绍世界其它国家成功的 family planning 范例时自然就不能将之混同于中国的计划生育政策。中国的计划生育政策绝对不能翻译为 family planning ，翻译为 family planning 就是赤裸裸的对国际社会的欺骗。中国的计划生育政策，较为准确的翻译应是 one- child policy 。其实，相对于 family planning ，中国的计划生育实为政府强制性执行的国家生育计划，因此可以翻译为 forced government planning 。布朗先生不傻，他怎么可能将中国的 forced government planning 当作 family planning 的典范向全世界推广呢？ 在 《 B 模式 4.0 》中，我没有找到布朗先生坚决支持中国的计划生育政策的证据。武夷山老师认为，布朗先生 作为在美国的学者，在主流意识形态都认为中国搞计划生育就是侵犯人权的情况下，他不怕挨骂做出自己的独立判断，我认为这反而是真正学者的表现。很遗憾，在 《 B 模式 4.0 》中我没有看到他这种 真正学者的表现。他连中国的计划生育都不敢提，更别说逆美国主流意识形态而对侵犯人权的计划生育唱赞歌了。 或许，布朗先生虽然不敢高喊坚决支持中国的计划生育政策，但他可能用实际行动支持中国的计划生育政策，比如据说他写的《谁来养活中国？》就是提供了一个在中国搞计划生育的合理性基础。虽然我还没有看过他的《谁来养活中国？》，但是我想，他即使是认为粮食问题可能为中国的发展带来制约甚至灾难，实际上就是支持中国减少人口，他也是不敢公开支持中国的计划生育政策的。从他在 《 B 模式 4.0 》关于 family planning 的成功经验推介中，我们可以推测他所支持的减少人口的方式也是 family planning 那种。 布朗在 2008 年 6 月接受《环球时报》专访时曾经表示： 中国对世界的贡献是 计划生育 和淡水渔业。我们不知道他的英文原文如何，仅按翻译的中文意思来理解他似乎是对中国的计划生育的褒奖。或许这可以作为它坚决支持中国的计划生育政策的证据？果真如此的话，那就很难理解他为什么不在他的 《 B 模式 4.0 》中介绍一下中国的计划生育对世界的贡献。或许，当时他是来中国访问，为了讨好中国（政府），而《 B 模式 4.0 》则是向全世界发行，他才不敢冒天下之大不韪？ 或许，人是复杂的，读他的一本书并不能完全了解他的全部思想，听他说的一句话也不能代表他的真实想法。我依然还是那句话：假如布朗坚决支持中国的计划生育政策，他就不配称为真正的学者。只是从他的《 B 模式 4.0 》来看，他是支持 family planning 的。或许他潜意识里愿意见到中国人口减少的结果，而不管这个结果是如何得来的。但正如武夷山老师说的，他不见得会支持中国计划生育过程中的一些野蛮做法。 2010-7-8
标签: 布朗
