| Songliao basin is one of the most important petroliferous basins in China. Including the study area, to the south of Binzhou Line in the north of Songliao Basin is an important oil and gas production area in China.Microfacies was one of the absolutely necessary contents on the research of reservoir. It could reflect the sedimentary rocks which deposited in the same sedimentary condition, and it was the most basic component unit in sedimentary system. The type and the spatial distribution of microfacies was always one of the most important contents in hydrocarbon exploration and exploitation, and it was always the foundation of the single well and multi well evaluation. The microfacies had not only controlled the lithology but also had close relation with the physical properties. The sediment rocks which deposited in different sedimentary environment had different forms, components and structures, and the degree of the diagenesis was also different, such as the cementation types, cementation degree and the difference of the absolute content in autogenous clay. These differences resulted in different porositys and permeabilitys. As a result, the same type sand bodies had different reservoir properties. In addition, the microfacies controlled the movement disciplinarian of oil and water, so the spatial distribution of the microfacies was one of the most important evidences on the prediction of movement disciplinarian of oil and water in thin layers. Therefore, the research on the microfacies was one of the foundations to study the reservoir.Reservoir heterogeneity was the basic character of the reservoir, including the lithology, physical property, geoelectric and microscopic pore and some other characters who's heterogeneity in the three dimensional space. To study the reservoir heterogeneity was actually to study the anisotropy of the reservoir, including qualitative and quantitatively description on the characters of the reservoir and the spatial changed disciplinarian, in order to supply an accurate geological model for the reservoir simulation research. The research on the reservoir heterogeneity had an important guiding function to the oil and gas field exploration and exploitation, especially for the research on the movement disciplinarian of the oil, gas and water, and its also had an important significance to increase the recovery factor of oilfield.The purpose of this paper was mainly based on the available regional geological data, geophysical data, logging data and test data, such as source rocks and reservoir properties. Then carried out the research on the distribution of sedimentary microfacies and reservoir heterogeneity. (1) the significance of study sedimentary microfacies: 1) In order to understand the sand body geometry, size, distribution, and the connectivity in the vertical and horizontal directions and so on; 2) in order to understand the physical properties of the reservoir. (2) the significance of study reservoir heterogeneity: (1) primarily for the latter part of the development of oil field(such as well spacing, water injection, etc.); (2) prediction the distribution of the remainjing oil at the late of the oil exploitation period.Based on the regional sedimentary environmental analysis and the small layer data, the sand layer could be analyzed by layer and render connecting-well sedimentary microfacies profile so as to determine the depositional environment of the reservoir and the spatial distribution changes of sand body. The methods of study was: First, from the core well of single well to discrimination the facies, then determining the relationship between lithology and electric to analyze the logging facies, establishing the logging facies modes; and then identifying the logging facies of the single sand body of the development wells; Finally, identifying the microfacies of the small layer and the single sand body, meanwhile marking the result on the planer map and drawing out the small layer microfaies map.Reservoir heterogeneity primarily included the planer heterogeneity, interlay heterogeneity and in-layer heterogeneity.From the above research, this article made the following preliminary results:1. The study area had divided into two kinds of subfacies and six kinds of microfacies. The two kinds of subfacies included delta front facies and shore shallow lake subfacies. Six kinds of Microfacies included distal bar, blanket sand, interdistributary estuary in delta front, bar sand ,beach sand and shore shallow lacustrime lake clay microfacies.2. Established six kinds of logging mode. They were distal dam, blanket sand, interdistributary estuary in delta front, beach sand, bar sand and shore shallow lacustrine lake clay microfacies logging facies mode.3. From the connecting-well sedimentary microfacies profile, it could be seen that: in the horizontal, the distal bar sand body were well connected in the east west direction, but were not well connected in the south north direction. In the horizontal, the blanket sand were well connected in the south north direction, but were not well connected in the east west direction. The bar sand and beach sand were well connected in the south north direction, especially in the middle area, and the connectivity was not so well in the east west direction. In the vertical, the connectivity of the middle part was relatively better than that in the upper parts and the lower parts, especially ,for example, Pâ… 1, Pâ… 2 and Pâ… 4 small layer sand body. The well connected sand bodies always presented sheet forms, and the less well connected sand bodies presented lens forms.4. By adding up the correlation of the microfacies of each small layer with the sandstone percent, it could be concluded that the sandstone percent of bar sand was the highest, the second was distal bar, the third was the beach sand, and the lowest was blanket sand, except the sandstone percent of Pâ… 2 and Pâ… 6 small layers. From the sedimentary microfacies plan of Putaohua reservoir, it could be identified two kinds of subfacies, and six kinds of microfacies. The sequence from north to south was delta front facies and shore shallow lacustrime subfacies. The north of the delta front sudfacies was blanket sand microfacies, and the south of the delta front subfacies was distal bar microfacies. In the shore shallow lacustrime subfacies, the beach sand microfacies was presented sheet form, and the bar sand microfacies was presented banding form which were distributed parallel to the shore of the lake.5. Described the reservoir heterogeneity respectively from the planar heterogeneity, in-layer heterogeneity and the interlayer heterogeneity. The planar heterogeneity of Pâ… 2,Pâ… 3,Pâ… 6å’ŒPâ… 7 small layers were more serious, the second serious were Pâ… 1 and Pâ… 5 small layers, and the weakest was Pâ… 4 small layer. The in-layer heterogeneity of distal bar microfacies was the most serious, the second serious was bar sand microfacies, the third serious was blanket microfacies and the last was beach sand, The sandstone density of Pâ… 1,Pâ… 2,Pâ… 4 small layers were the largest and the lamination factor was also larger. It showed that the sand thickness of these three small layers more developed, while the layer number also well developed. In conclusion, the interlayer heterogeneity of the three layers was more serious;The sandstone density of Pâ… 5 and Pâ… 7 small layers developed moderately, and the lamination factor also developed moderately. In conclusion, the interlayer heterogeneity of these two small layers was serious; the sandstone density of Pâ… 6 small layer developed moderately, but the lamination factor less developed, reflecting weaker interlay heterogeneity. The sandstone density of Pâ… 3 small layer developed lower, and the lamination factor developed moderately, reflecting serious interlay heterogeneity. The sandstone density of Pâ… 8 small layer less developed, and the lamination factor also less developed, reflecting serious interlay heterogeneity.6. The reservoir heterogeneity was controlled by sedimentary microfacies, lithology and dianenesis.
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