Research On Reservior Characteristics And Target Area Preferred Of Chang3 In Qiaol9 Area

Ordos basin is one of the earliest basins found that contains oil in China, and it is also the second largest basin containing rich oil and gas. Yanchang Formation of Ordos basin is kind of subsiding and clastic inland lake basin. With progress in exploration and development in Erdos, new wells is drilled with oil and the rich data obtained from wells make it possible to study in-depth Yanchang Formation Chang3 oil-bearing,and based on the data, it is realized that Yanchang Formation Chang 3 oil-bearing is not only the main source rock,but also good reservoir and it contains good conditions favorable to self-generation and self-storage. The turbidites existing in deep water region as oil reservoir break the regular notion that deep water region is not suitable to be explored.Marker and base level cycle converted point hierarchical strategy are adopted to analyze the region structural feature and no obvious evidence can be found that the developed nose-like structure in the region can control oil and gas well. Based on core type, heavy minerals feature, ancient river direction and previous research results, it is regarded that the source material of Chang 3 oil-bearing of Formation mainly comes from Southwest and Northeast. Systematic research of sedimentary system in Chang 3 is studied based on analyzing source material in the region, it is regarded that the target region in research area is delta sedimentary system developed, in which Chang 33 to 31 history period is contained, and delta area was decreasing, lake shoreline was shrinking, and Chang 31 to 32 had wide turbidites and fine reservoir had formed. In the research area, microscopic-analysis on casting thin sections and SEM method is used to show that reservoir lithology is main mine feldspar, and the porosity type is mainly intergranular. In total, the physical properties is not good, belonging to ultra-low porosity ultra-low permeability, and by comparing with the change trend of permeability and porosity, permeability and porosity has good correlation relationship. The reservoir is seriously heterogeneous in macroscopic and microscopic aspect, and the interlayer frequency is decreasing from 31 to 33, and it is clustered distributed in plane graph. The reservoir feature of lithology,physical properties,oiliness,electrical property are established and the porosity,permeability and oil saturation are recognized once again. Then reservoir evaluation is done and the formation is classified into 5 levels which provides basis for predict favorite oil and gas-bearing regions. Besides, sedimentary environment and diagenesis are the main factors affecting reservoir physical property and the widely developed fissures provide good channels for oil and gas migration.According to the research, good featured turbidite submerged fan is good place for oil and gas accumulation. Meanwhile, Chang3 turbidite lies close to lake-basin center, and it has good source-reservoir-cap assemblage, and the sand depth at turbidite submerged fan is high. With the combination method of oil production, oil production oil test data and comprehensive reservoir evaluation, favorable target area prediction is selected and the next direction of exploration is suggested.