依兰—伊通断裂带以东白垩系沉积盆地构造特征及油气潜力

Tectonic characteristics and oil-gas potentials of Cretaceous sedimentary basins in the east of Yilan-Yitong Fault Zone

依兰—伊通断裂带以东白垩系沉积盆地已开展了一定的勘探工作,部分盆地尚未勘探。为了预测研究区的油气勘探潜力,应用区内地震、地球化学、试油数据等资料,从构造演化和成因类型等方面分析沉积盆地构造特征,在岩样分析的基础上对比烃源岩评价指标并分析资源潜力。研究结果表明:以佳木斯隆起为主的北强南弱的拼合地块活动强度与同期活动的断裂共同控制沉积盆地的形成与展布,北部沉积盆地规模大,向南部过渡为小型沉积盆地,以残留单断式为主,北部沉积盆地后期改造强度比南部大得多。各断陷盆地油气形成条件迥异:北部烃源岩有机碳含量较高,但氯仿沥青“A”含量极低,热演化程度极高,Ro最高达3.7%,所以北部沉积盆地的烃源岩可能以生气为主;南部沉积盆地有机质丰度较高,有机质类型好,高成熟—过成熟烃源岩适于生油,未熟—低熟烃源岩可能形成油页岩。研究成果为依兰—伊通断裂带以东白垩系沉积盆地的油气勘探提供了理论依据。

A certain exploration works have been done in Cretaceous sedimentary basins in the east of Yilan-Yitong Fault Zone, but some sedimentary basins have not been explored. In order to predict the potentials of the oil and gas exploration in the study area, with the help of the seismic, geochemical, oil testing data and so on, the structural characteristics of the sedimentary basins were analyzed from the viewpoints of the structural evolution, genetic type and so forth, and moreover the evaluating indexes of the hydrocarbon source rock were contrasted and the source potential was analyzed on the basis of the rock sample analysis. The study results show that the formation and distribution of the sedimentary basins are controlled by both the activities strength strong in the north & weak in the south of the split block taking Jamusi Uplift as the main form and the faults with the concurrent activities, the scale of the northern sedimentary basin is pretty bigger and transfers to smaller sedimentary basin towards the south taking the residual single fault as the principal form, the later reformed strength of the north sedimentary basins is rather serious than that of the south. The generating conditions of the hydrocarbon in each fault basin are rather different: in the north, the content of the organic carbon is pretty higher, but the content of the chloroform bitumen “A” is extremely lower, the thermal evolution degree is very higher, the peak R o is up to 3.7%, therefore the gas is maybe mainly generated in the northern sedimentary basins;while in the southern sedimentary basin, the organic matter abundance is pretty higher and the organic matter type is pretty better as well, the high-maturity and over-maturity hydrocarbon source rocks are prone to generate oil, while the immature and low-maturity hydrocarbon source rocks are likely to form the oil shale.