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筛选有机地球化学参数中不受或者很少受其他地质因素干扰的地球化学指标作为油气示踪的有效参数,探讨塔中地区泥盆系东河砂岩中油气充注方向。泥盆系东河砂岩中地球化学指标(1,3,6-)/(1,3,6-+1,2,5-)三甲基萘(TMNr)、4-甲基二苯并噻吩/1-甲基二苯并噻吩(4-/1-MDBT)、咔唑类化合物含量(W)、C2烷基咔唑的结构类型(G1、G2、G3)存在一定的运移分馏作用。表现为随着油气运移距离的增长,TMNr值、4-/1-MDBT值、W值和G3值呈现出有序的降低;而C2烷基咔唑的结构类型G1值、G2值和C3-咔唑/C2-咔唑值则随着石油运移距离的延伸而逐渐增大。根据对上述地球化学指标的综合分析,塔中东部泥盆系东河砂岩的油气充注表现为自NW向SE方向和自SE向NW方向往构造高部位充注,塔中西段则表现为自NW向SE方向和自NE向SW方向充注。同时研究结果也表明该区的油气可能经历了相当长距离的运移。
The geochemical indexes of organic geochemical parameters that are not or rarely disturbed by other geological factors are screened as effective parameters for oil and gas tracing to investigate the direction of hydrocarbon filling in the Devonian Donghe sandstone in the Tazhong area. Geochemical indicators (1,3,6 -) / (1,3,6 - 1,2,5-) trimethylnaphthalene (TMNr), 4-methyldibenzothiophene There is a certain shift of fractionation between the structure of C2 alkyl carbazoles (G1, G2, G3) and the content of carbazoles (W). The TMNr value, 4- / 1-MDBT value, W value and G3 value showed an orderly decrease with the increase of hydrocarbon migration distance. However, the structure type G1 value, G2 value and C3 value of C2 alkyl carbazole The carbazole / C2-carbazole values gradually increase with the migration distance of petroleum. Based on a comprehensive analysis of the above geochemical indicators, the East-Central Devonian sandstones in the Middle Paleo-Ehrysian oil-gas filling are characterized by filling from NW to SE and from SE to NW toward the structural high, NW to SE direction and from NE to SW direction charge. The results of the study also show that the oil and gas in this area may have undergone a considerable distance migration.