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Gas Charging Ability Evaluation Of The Upper Palaeozoic Group In The Middle Of Ordos Basin

Posted on:2017-05-17Degree:MasterType:Thesis
Country:ChinaCandidate:H Q ZhengFull Text:PDF
GTID:2180330488963475Subject:Unconventional oil and gas geology
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Ordos basin, which is the second largest petroliferous basin of our country, located in the middle of China. Abundant tight sand gas have been found in Upper Palaeozoic Group. In today’s world, the tense international situation, frequent fluctuations in oil prices, and that energy conservation construction is at the basic stage in our country make it difficult for us to deal with. Besides, on the one hand, the energy structure based on coal promote the rapid economic development in China, on the other hand, it also brings a series of problems such as environment, geological disasters. Adjust the energy structure, intensify our efforts to gas exploration and development will effectively relieve the above situations and play an important role in realizing sustainable development.After decades of exploration, several large-scale tight sand gas fields gradually have been found,such as Yulin, Shenmu, and Sulige. There is no doubt that the quantitative evaluation on the degree of gas charging in Upper Palaeozoic Group will make an indication to predict the next exploration target.The upper palaeozoic coal hydrocarbon source rocks of Ordos basin mainly distributed in the ben-xi group, tai-yuan and shan-xi formations, and most has entered into high mature stage. A set of deltas contributed to form widely distributed sandstone reservoir. According to the gas-source correlation results in su-lige region by predecessors, on the basis of the natural gas geological reserves scale contrast, we conclued that only 20% gas discharged from hydrocarbon source rocks charged into the ordovician and shi-qianfeng group,the remaining 80% gas filling in the benxi group- he 8 sandstones.In terms of the quantitative charging of gas, as early as 1991,G.Demaison et al have put forward to apply Source Potential Index which represents the quantity of oil and gas generated from source rocks per unit area to reflect the charging ability of oil and gas in petroleum systems. But this principle only consider the factor of the source rocks, it cannot effectively reflect the actual situation of the Ordos basin. Based on this, considering that the hydrocarbon source rocks in Upper Palaeozoic of the Ordos basin generally generating hydrocarbon and overlapping with the widely scattered reservoir, the gas migrating in a short distance formed a large area of tight sand gas reservoir, GCI(Gas Charging Index),a simplified mathematical model,is raised to quantitative evaluate the degree of gas enrichment, it mainly includes the involved parameters intensity of hydrocarbon generation, hydrocarbon expulsion rate, reservoir thickness, and porosity.Centered around four parameters, at first, on the basis of previous research results, sedimentary background and development condition of hydrocarbon source rock and reservoir have been concluded. Secondly, according to the organic geochemical test results, I got the organic geochemical characteristics of hydrocarbon source rocks. Thirdly, by selecting several typical samples, a thermal pressure simulation experiment has been made. Fourthly, author calculates the intensity of the hydrocarbon of source rocks by organic hydrocarbon production rate method. At last, the gas charging ability is evaluated quantitatively in research area according to the principle of Gas Charging Index.
Keywords/Search Tags:Ordos basin, Thermal pressure simulation experiment, Hydrocarbon generation intensity, Charging ability
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