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ทุกวันนี้กลุ่มบริษัทเชฟรอน ของสหรัฐอเมริกามีส่วนแบ่งปริมาณปิโตรเลียมที่พิสูจน์แล้วในการสัมปทานปิโตรเลียมในประเทศไทยโดยคิดปริมาณปิโตรเลียมคิดเทียบเท่าน้ำมันดิบ ประมาณ 1,255 ล้านบาเรล ถือเป็นผู้ที่ได้สัมปทานอันดับ 1 ในประเทศ และมีสัดส่วนถึง 50.7%
ดังนั้นเชฟรอนเมื่อได้แหล่งพลังงานจากประเทศไทยในราคาค่าสัมปทานที่แสนถูก ครองตลาดเป็นอันดับหนึ่ง แถมยังจะมีสัมปทานราคาค่าภาคหลวงต่ำๆอีกกำลังจะเริ่มเปิดสัมปทานครั้งที่ 21 ในเดือนกรกฎาคม พ.ศ. 2555 นี้ แต่เมื่อภาคประชาชนเริ่มตื่นรู้การเสียผลประโยชน์ทางพลังงานของชาติไทยเพิ่มมากขึ้น การเคลื่อนกองกำลังเรือเข้ามาในภูมิภาคเอเชีย-แปซิฟิกของสหรัฐอเมริกาจึงกลายเป็นปฏิกิริยาตอบสนองเพื่อดูแลคุ้มครองผลประโยชน์ของสหรัฐอเมริกาเอง
ทั้งนี้เมื่อวันที่ 26 กรกฎาคม พ.ศ. 2554 ห้องปฏิบัติการการขับเคลื่อนก๊าซหรือของเหลวที่พ่อออกมาด้วยความเร็วขององค์การนาซ่า ที่เรียกว่า The NASA Jet Propulsion Laboratory ได้ประกาศเป็นหุ้นส่วนกับเชฟรอน ในอันที่จะพัฒนาความก้าวหน้าทางเทคโนโลยีสำหรับสิ่งแวดล้อมที่หยาบกระด้าง รวมทั้งในอวกาศและบนบก เช่น ระบบปั้ม, วาล์ว, การบริหารจัดการ, ระบบตรวจสอบบ่อลึก โดยเชฟรอนระบุว่าเทคโนโลยีเหล่านี้ต้องการที่จะค้นหาน้ำมันและก๊าซทั้งบนโลกและอวกาศได้มีประสิทธิภาพมากยิ่งขึ้น
โดยเฉพาะอย่างยิ่งเครื่องบินสำรวจ ER2 นั้น ที่จะเข้ามาสำรวจในประเทศไทยโดยองค์การนาซ่านั้น มีประวัติหลายด้านทั้งการสำรวจชั้นบรรยากาศ การทำงานร่วมกับดาวเทียมในการสำรวจน้ำมันและก๊าซธรรมชาติ และการดัดแปลงอุปกรณ์เพื่อจารกรรมข้อมูลทางการทหาร
Geophysics Unit of Menlo Park, CA (GUMP)
U.S. Geological Survey - Western Region - Geology and Geophysics
Aeromagnetic Survey Over U.S. to Advance Geomagnetic Research
A proposed high-altitude survey of the United States offers an exciting and cost-effective opportunity to collect magnetic-anomaly data. Lockheed Martin Missile and Space Company is considering funding a reimbursable ER-2 aircraft (Figure 1) mission to collect synthetic aperture radar (SAR) imagery at an altitude of about 21 km over the conterminous United States and Alaska. The collection of total and vector magnetic field data would be a secondary objective of the flight. Through this "piggyback approach," the geomagnetic community would inherit invaluable magnetic data at a nominal cost. These data would provide insight on fundamental tectonic and thermal processes and give a new view of the structural and lithologic framework of the crust and upper mantle.
Fig. 1. The ER-2 is the NASA remote sensing version of the U.S. Air Force Lockheed U2-R, which replaced the older U.S. Air Force U2. The superpods and wingtip pods are the proposed locations of the magnetometers.
Utility of High-Altitude Magnetic-Anomaly Data
Magnetic-anomaly data reflect variations in the distribution and type of magnetic minerals—especially magnetite—in the Earth. Magnetic rocks can be mapped from the surface to great depths in the crust, depending on their dimension, shape, and magnetic properties, and on the character of the local geothermal gradient. Magnetic-anomaly data have played a pivotal role in advancing the geologic sciences (for example, in the birth of plate tectonics from the discovery of seafloor magnetic stripes). They provide the geologic framework for solving a wide range of problems that affect society and the environment, such as understanding geologic processes, managing natural resources, and assessing natural hazards.
Magnetic-anomaly data provide important information about regional geology, especially where rock outcrops are scarce or absent, as in offshore economic zones and in covered land areas. They are particularly useful in studying the distribution of magnetic mafic, ultramafic, and plutonic rocks (Figure 2). In short, important insights on the complex geologic history of the crust and possibly the upper mantle (Figure 2) are gained in studying the lateral variations in magnetization across the United States.
Fig. 2. Hypothetical cross section of the continental crust and upper mantle, showing the lateral complexities in the distribution of magnetic mafic, ultramafic and plutonic rocks. Generalized from Fountain and Christensen [1989].
The information contained in a magnetic survey is largely restricted to a specific band of the wavenumber spectrum, with the position of this band and the ability to resolve it being primarily a function of the survey's altitude and size. Although the 20–22 km altitude of the ER mission was established independently of the requirements of geologic or geomagnetic studies, it will be nearly optimal for bridging the gap between existing low-altitude aeromagnetic data (generally at altitudes of 1 km or less) and satellite magnetic data (at altitudes of about 450 km) (Figure 3).
Fig. 3. Amplitude spectra of magnetic surveys flown at three altitudes. Each spectra has been normalized to a maximum of 1. The solid black-shaded area is the spectrum that is expected from a survey flown at 450 km, the nominal altitude of the NASA 1979–1980 Magsat mission. The light-shaded area is the spectrum at 1 km, the altitude of a typical aeromagnetic survey. The medium-gray-shaded area is the spectrum that is expected from the high-altitude aeromagnetic survey. The dashed line is at amplitude of 1/e. Magnetic layer assumed to be 10 km thick. The shapes of the spectra depend only on the depth to the top and thickness of the layer. Thus they are applicable for both total-field and vertical-field surveys.
Because there is little overlap between the spectra from satellite and low-altitude aeromagnetic surveys, a significant part of the spectrum (wavelengths of 200–900 km) is poorly known. This part of the spectrum is critical to crustal studies; it is about the same length scale as major geologic structures, such as the Cascade Range, the Basin and Range province, and the Midcontinent Rift. The high-altitude magnetic-anomaly data will eliminate the gap between wavelengths of 200 and 900 km, and, together with low-altitude aeromagnetic and satellite magnetic data, provide information across the spectrum.
Examples
Several applications of the high-altitude magnetic-anomaly data are envisioned. For example, these data will significantly add to the U.S. compilation of low-altitude aeromagnetic surveys, which represents a national resource that is fundamental to geoscience investigations. It provides key geologic, tectonic, and thermal information. This data set is currently based on a patchwork of over 1,000 airborne and shipborne surveys, acquired over a period of 40 years to address a variety of objectives.
Significant mismatches exist between many survey data sets, some exceeding several hundred nanoteslas—an order of magnitude greater than the amplitudes of magnetic anomalies caused by some of the sources of interest. For surveys of about the size of a 1°×2° quadrangle, a properly conducted high-altitude aeromagnetic survey will significantly reduce data mismatches at survey boundaries and thus greatly expand the utility of the low-altitude magnetic data over a much broader range of wavelengths.
A consistent datum for all aeromagnetic surveys will improve both qualitative and quantitative interpretations. For example, they will be beneficial for geological mapping, particularly where magnetic maps are used to extrapolate observations from outcrop to covered regions, and for quantitative comparisons of magnetic properties of rock units in different parts of the United States. A correctly merged aeromagnetic map of the conterminous United States may be the single most important legacy of the high-altitude mission.
Interpretations of the high-altitude data will provide new insights on the structure and evolution of the crust and possibly the upper mantle. For example, there are few direct methods for characterizing crustal temperatures. Spectral analysis of the high-altitude aeromagnetic data may lead to estimates of crustal depths where elevated temperatures (above about 580°C) cause rocks to lose their magnetic properties. Thus these data could be used to study crustal temperatures and to improve the national heat flow map. The advancement in our understanding of crustal temperatures could benefit many socioeconomic studies. This knowledge could be used to assess geothermal resources and—since the mechanical behavior of the crust is highly temperature dependent—provide new insights on crustal stability related to volcanoes and fault systems.
The large lateral dimensions of the high-altitude aeromagnetic survey will also provide important information about the separation of magnetic fields of crustal and core origin. When the geomagnetic field is expressed as a spherical harmonic expansion, the core and crustal components overlap between harmonic degrees of 12 and 15. It is in this wavelength region where core fields merge with crustal fields. The dimensions of the high-altitude aeromagnetic survey will be several times larger than these wavelengths and thus will be useful in analyzing the overlap between core and crustal fields.
A consistent, high-quality survey could lead to a better understanding of the statistical aspects of the crustal field over the United States, which should lead to improved core-crustal separations worldwide. The importance of the high-altitude magnetic data to core-crustal separation studies will be enhanced if the ER-2 mission occurs during the Oersted magnetic satellite mission scheduled to launch in June 1997. Moreover, the regional crustal field defined by the high-altitude magnetic survey can be added to the improved core field to provide magnetic models needed in higher precision positioning, such as directional drilling by oil and gas exploration
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