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海相碳质岩层中细粒黄铁矿的低温放热氧化可以导致自燃。结果这些岩层中的有机质作为燃料消耗掉了,但与烧过的煤层和褐煤层又有不同,这里的主岩可以在燃烧后保留下来。它们发生了热变质作用,有时还有局部或完全的熔融。燃烧变质带经常与油田伴生。它们的分布既可与源岩的地表露头相联系,又可以与油气藏的渗漏相关。对加利福尼亚州南部蒙特雷组和锡斯阔克组一套燃烧变质样品所进行的磁性研究表明,不管是热变质岩样还是熔融岩样,其磁化强度和磁化率都有数量级的增加。这些变化既反映了新磁性矿物的生成(主要来自硫化铁的氧化),也说明它们获得了热剩磁。加利福尼亚州南部三个油田燃烧变质带的地面磁测揭示,与变质和熔融岩石有关的异常高达2000Υ。在委内瑞拉的马塞利纳组和以色列的盖赖卜组及塔基耶组(斑点带),大规模的航磁异常也与广阔的燃烧变质带有关。在产油区通过的识别燃烧变质作用引起的磁异常,说明小间距的低空航磁洲量可能是一种有效的油气勘探方法。
Low-temperature exothermic oxidation of fine-grained pyrite in marine carbonaceous rocks can lead to spontaneous combustion. As a result, the organic matter in these rock formations is consumed as a fuel, but different from the burnt seam and the lignite, where the main rock can be retained after combustion. They undergo thermal deterioration, sometimes with partial or complete melting. Burning metamorphic belt often associated with the oil field. Their distribution is not only related to the surface outcrop of source rocks but also to the leakage of reservoirs. Magnetic studies of a set of combustion metamorphic samples from the Monterrey and Sesquisac formations in southern California show that both the magnetization and the susceptibility increase in either the hot metamorphic or molten rock samples. These changes both reflect the formation of new magnetic minerals (mainly from the oxidation of iron sulfide), also shows that they obtain the thermal remanence. Ground magnetometry of the combustion metamorphic zones of the three fields in southern California revealed that the anomalies associated with metamorphic and molten rocks were as high as 2000 °. Large-scale aeromagnetic anomalies are also associated with extensive combustion metamorphic zones in the Marcelinas Formation in Venezuela and in the Qai Lai Bu Formation and the Takiye Formation in the Israel (dot zone). The identification of magnetic anomalies caused by combustion and metamorphism passing through the oil-producing region shows that low-lying magnetic submarine spacing may be an effective oil and gas exploration method.