Title: Comprehensive Application of Fluid Properties and Seismic Interpretation in Research on Oil and Gas Migration: An Example of Bashituopu Reservoir in Markit Slope in Tarim Basin
Abstract: Oil and gas migration studies mainly focus on the comparison of the types and contents of biomarkers in oil and gas at the zone level, while the study of crude oil distribution and migration path in complex reservoirs at the stage of development is a difficult problem. Because of the similarity of biomarkers properties in small area, this method is not applicable. This study propose a new method to determine oil and gas migration and accumulation units at the reservoir level. Bashituopu reservoir in Markit slope in the Tarim Basin is a typical secondary oil and gas reservoir. Commercial oil and gas has been obtained in Carboniferous bioclastic limestone section, Xiaohaizi limestone section and Devonian Donghetang sandstone formation. However, the spatial distribution of crude oil is not as a whole, and new methods are needed to determine the crude oil development unit. This study comprehensively applies fluid property analysis and seismic interpretation technology. Firstly, detailed interpretation of faults and unconformities is carried out in stages and scales, but the key problem is to determine the role of different faults in oil and gas migration. Secondly, fluid properties from the early development wells are classified and compared. The study focuses on spatial differentiation of the regular physical properties of crude oil, formation water and associated gas. Thirdly, on the basis of tectonic evolution and fracture distribution, the fractures and unconformity surfaces that can be used as channels are determined, and then the horizontal migration direction and vertical migration path of crude oil are determined, thus many development units are subdivided in the region. The application example of this method is Bashittuopu reservoir in Markit slope of the Tarim basin: 1. The formation water property shows that, the water density decreases from west to east in Donghe sandstone section, while the variation of water quality in bioclastic limestone section is not obvious and is not controlled by structural morphology; in well group 601, the upper and lower formation fluids may be vertically connected and there are communication faults; 2. The nature of crude oil: in Donghe sandstone section. Both the Western well area and the bioclastic limestone section show that the crude oil density is higher than that of the eastern well area, and the wax content and asphaltene content of crude oil decrease eastward, indicating that the adjustment direction of crude oil migration is from west to East in these two formations; 3. the nature of natural gas: in Donghe sandstone section, the nature of natural gas is controlled by structure; the Spatial differentiation of nature of natural gas in bioclastic limestone section is not distinct; and the methane content of natural gas is lowest in Qun601 well. The highest relative density and CO2 content are found in Qun601 well, where an upward gas supply port may exist. Through this method, new geological knowledge is obtained: the latest migration direction of crude oil in this area is from west to east; within the Qun601 well area, the main fault may connect Donghe sandstone and bioclastic limestone longitudinally; and in well Mai3 and Qu3 area, there is a fracture connecting bioclastic limestone and Xiaohaizi formation limestone longitudinally. This example proves that the comprehensive application of fluid property analysis and painstaking seismic interpretation technology can achieve useful results on oil and gas migration research in local-scale area, which is conducive to well deployment at reservoir development stage.
Publication Year: 2020
Publication Date: 2020-01-01
Language: en
Type: book-chapter
Indexed In: ['crossref']
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