1、 Formation Mechanism and Distribution of Paleogene-Neogene Stratigraphic Reservoirs in Jiyang Depression 1 中文 7700 字 Formation Mechanism and Distribution of Paleogene-Neogene Stratigraphic Reservoirs in Jiyang Depression Abstract During Paleogene-Neogene period, multiple scale unconformities had bee
2、n formed in Jiyang depression, which provided favorable conditions for stratigraphic reservoirs. In recent years, various Paleogene-Neogene stratigraphic reservoirs in Jiyang depression have been found, and proved reserves were rising significantly, which fully showed a great exploration potential f
3、or this kind of reservoirs. But the practice of exploration in recent years indicated that the unconformities carrier system and its ability of sealing, petroleum migration and its accumulation model, distribution of stratigraphic reservoirs are uncertain, which deeply restrict the exploration degre
4、e of stratigraphic reservoirs in Jiyang depression Based on the analysis of a large number of exploration wells and seismic data for Typical reservoirs, the paper analyses unconformities construct and its effect to generation in the PaleogeneNeogene, and summarize the distribution pattern of stratig
5、raphic reservoirs based on petroleum mechanism and accumulation model. Finally, a highly quantitative prediction modclof height of pools in stratigraphic reservoirs was established, the research results effectively guided the explorationPra- ctice of stratigraphic reservoir . There are four macro un
6、conformity types of PaleogeneNeogene formation which including truncation-overlap, truncationparallel, paralleloverlap and paralel unconformity in Jiyang depression.Besides truncation-overlap unconformity lies in slopes of depression, and parallel unconformity developed inside of depression,another
7、two types lie in local areas. Unconformity can be developed vertically three-layer structure which including unconformity roof rock, weathered clay layer and semi-weathered rock. It also Can be twolayer structure if without weathered clay layer.And part of semiweather rock Can be form a hard shell a
8、ccuse of its filling process during the later stage. Geological characteristic of the structure layer of unconformity is different in lithology,mineralogy, element geochemistry and weather degree index. Based on optimal partition of sequential number and principal component analysis, logging quantif
9、ication recognition method about unconformity structure layers were established, on which effective identification of unconformitystnlcture layers can bu achieved Formation Mechanism and Distribution of Paleogene-Neogene Stratigraphic Reservoirs in Jiyang Depression 2 in the case of no rock core. Th
10、e formation of various unconformity structure types is Formation Mechanism and Distribution of Paleogene-Neogene Stratigraphic Reservoirs in Jiyang Depression 1 related to many factors such as, parent rock lithology, interval of deposition hiatus, palaeotopography,and preservation conditions, which
11、aretogether to control spatial distributions of unconformity structure types . Macro styles and its vertical structure of unconformity can be effected as a blocking, reservoir, trap or carrier system.Blocking affection to fluid depends on weathered clay layer,hard shell of semi-weathered rock and mu
12、dstone. So petroleum migration and accumulation units is relatively independence above and belowunconformity if structure layers mentioned above existed. Reservoir affection is due to permeable rock, including roof sandstone .Semi-weathered sandstone, semi-weathered carbonate rock, semiweathered ign
13、eous rock and semi-weathered metamorphic. Trapcontrolling affection related to macro unconformity type and its juxtapose to permeability and impermeability rock above and below unconformity. It is easy to develop stratigraphy traps where the permeability and impermeability beds juxtapose in a trunca
14、tion-overlap unconformity, where up permeability and down impermeability in parallel-overlap unconformity, and down permeability and up impermeability beds juxtapose in a truncation-parallel. Transporting affection is owing to lateral continuity of permeable rock of unconformity. In a terrestrial ri
15、ft basin, petroleum migration in transverse or vertical short distance in local area, and is not conducive to petroleum long distance along unconformity, because interbedding pattern of mudstone and sandstone is dominated, and its physical property of mudstone improved poorly . Because of the long d
16、istance from resource to trap, migration and accumulation procese is very complicated. Accumulation process of Paleogene-Neogene stratigraphic traps can be summarized as following： allochthonous source rock , compound transportation , later period charging, buoyancy and pressure conversion driving f
17、or accumulation, and blocking by non-permeable layer of unconformity, Trap types and its distribution are controlled by unconformity structure styles. Petroleum distribution and its scale are controlled by generating ability of Source rock. Petroleum accumulation area is decided by positive tectonic
18、 units. If carrier system existed , oil column of stratigraphic reservoirs is effected by four main factors which including generation expulsion quantity,migrating distance, dip angle and capillary resistance of carrier layer. Based on the analysis of single factor, the prediction model of height of oil columu through multifactor regressions was established . Based on the model , the paper defruited favorable areas, which reserves in these areas exceed 1.5 x 1 08t .
