Shulou(Shulou.com)11/24 Report--

Former US Secretary of State Henry Kissinger once said: "if you control oil, you control all countries." Oil is called "the blood of industry". It is not only a non-renewable commodity, but also an indispensable strategic resource for national survival and development. it plays an inestimable role in ensuring national industrial, economic and social development and national defense security. Today, the editor continues to lead you to get close to oil and understand the past and present life of oil.

As mentioned by the editor before, there are six words in the oil industry-source, reservoir and cap circle operation and insurance (see for details: what is "black gold"). These six words briefly summarize the conditions needed for the formation of conventional oil and gas reservoirs. This time, Stone Science Popularization Studio will give you a detailed explanation of the "health" of oil.

✦✦ for source-reservoir capping ring transportation and guarantee

01 the theoretical basis of "Sheng" there are mainly two viewpoints on the formation of oil: "inorganic cause theory" and "organic cause theory". At present, most of the oil circle is more aware of the "organic cause theory". After all, oil itself is organic matter. We know that coal is formed by higher plants like ancient trees, but oil is formed by invisible microorganisms, such as algae, plankton, bacteria and so on. Oil is evolved from the remains of ancient lower creatures under reduced conditions of high temperature pyrolysis, perhaps the study of oil is the real "tomb robbing notes".

Fluorescence micrographs of various oil-generating substances after death, the lower organisms settle to the bottom along with mud debris in the ocean and are buried, and under the condition of anaerobic reduction, they are transformed into a solid called "kerogen" (if oxygen is present, the organic carbon will be oxidized to CO2 and run away). Kerogen is decomposed by heat to release oil and natural gas (just like we sweat when we are hot).

Green River Shale kerogen (B.P. Tissot et al., 1978) ✦✦

02 "raw" reaction conditions kerogen as a reactant, oil as a product, we still lack the reaction condition-temperature. Kerogen at different temperatures, due to different degrees of cracking, the length of carbon chain is different, the types of oil and gas are naturally different. The temperature is mainly achieved through burial depth or magmatism: the deeper the burial depth (such as the Tarim Basin) and the closer to the magma (such as the Bohai Bay Basin), the higher the temperature and the shorter the time required to generate oil. But the temperature can not be too high, after all, oil can only be generated at a specific temperature: if the temperature is too low, the biological action will decompose the kerogen to produce natural gas; if the temperature is too high, the organic matter will be further cracked to produce natural gas. Does it look a lot like the way you adjust the temperature of the water in the shower (laughter).

Oil and gas generation evolution diagram (Liang Fuhua et al., 1981) ✦✦

03 "raw" environment needs oil, which is simply "oil from stone". Under what circumstances can stones be formed to produce oil? Baichuan Huihai, with the weakening of the river transport, the coarse gravel stopped moving on the bank and shallow, while the center of the ocean is mostly stagnant environment, there is no strong hydrodynamic influence, and fine-grained sediments are mainly deposited in the deep. With the continuous sedimentation, the lower loose mud and sand wrapped with the remains of lower organisms are gradually compacted into one layer, thus forming fine-grained sedimentary rocks such as mudstone and shale rich in organic matter. This kind of rock that can generate oil is called "source rock".

Due to the seabed topography model map is in the anaerobic reduction environment, pyrite (FeS2) formed by the combination of Fe elements and S elements is dispersed in the rocks, coupled with the color of the organic matter itself, most of the source rocks are black. In a non-reductive environment, organic matter will be oxidized to form inorganic CO2. The Fe element will be oxidized to Fe3+, which makes the whole formation red.

Black Shale (Photo: popular Science website) ✦✦

04 shale oil two or three things may be that many friends will think of shale oil when they see "black shale". So what exactly is shale oil? As the name implies, shale oil refers to oil extracted from shale. Conventional oil and gas reservoirs have six aspects, such as "source-reservoir-cap circle transportation and protection", while shale oil is simply "self-generation and self-storage". Shale oil has no obvious process of "transportation". It is generated in shale and sealed in shale. Shale has several roles, achieving the integration of "source, reservoir and cap". In the process of conventional oil and gas reservoir exploration, we often think that the shale itself does not have enough "voids" to store oil and gas, and with the development of science, we find that there is oil and gas filling in the micron or even nanometer voids of shale. Permian and Jurassic in Junggar basin, Triassic in Ordos basin, Jurassic in Sichuan basin, Cretaceous in Songliao basin and Paleogene in Bohai Bay basin are the key research and development strata of shale oil.

Schematic map of basin distribution in China ✦✦

The theory of continental oil generation was established in the study of the early 20th century, and the "ocean" seems to be a necessary factor for oil generation. Foreign geologists believe that only the ocean can have a large number of low-grade organisms and form a stable and extensive stagnant environment, while most parts of China have long been terrestrial, without Meso-Cenozoic marine deposits, and do not have the necessary conditions for "marine oil generation theory". Therefore, China has been given the label of "oil-poor country". However, Chinese geologists believe that although we do not have an "ocean", "lakes" have a similar nature. Mr Li Siguang pointed out that "Mobil's failure does not prove that China has no oil to do". With the unremitting efforts of Chinese geologists, the theory of continental oil generation has emerged in China, which provides a basis for finding a large amount of oil in China's continental basins. Moreover, its establishment has promoted the rise and development of China's petroleum industry, made a great contribution to China's energy utilization, and laid an important foundation for the formation and development of China's petroleum industry. It also provides a new research direction for the development of petroleum geology as a whole.

Li Siguang (Source: China popular Science Writers Network)

The alternation of day and night is because the earth rotates from east to west on its axis; the seasons change only because of the north-south change of the sun's direct point. Fossilized shells in the Himalayas indicate that the mountains were once the sea; traces of plants were found under the Antarctic ice sheet, and perhaps there was spring in Antarctica. Across mountains and rivers, geologists have traveled all over the world; through the ages, human exploration of the earth has never stopped.

This article comes from the official account of Wechat: stone popular Science Studio (ID:Dr__Stone). Author: Wei Yezhou.

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