Study On Sedimentary Microfacies Of SⅡ15+16Unit Under Dense Well Pattern Condition In Northern Changyuan,DaQing

Northern Changyuan of Daqing is the research object of the paper including southern Lamadian oilfield and northern Sabei oilfield, and SⅡ15+16unit in Yaojia Formation is the research horizon. Utilized with core, logging and seismic data, guided by sequence stratigraphy and sedimentary, the paper studies on the purpose of the formation in the study area, including fine division and correlation, the distribution of sedimentary microfacies and recognition of single distributary channel. The conclusions indicate as follow:1. Based on the well logging records of8269wells, according to the principle of "contrasting the cycle, grading control, facies contraint, three-dimensional closed", the paper use a varity of methods for fine division and correlation, establishing unifield stratigraphic framework. The result is that the reservior of SⅡ can be divided into5Grade Ⅳand SⅢ divided into3, building the relation of sequence and sand group. The research horizon is in SII13-16sand group, which is further subdivided into Grade Vand GradeVI under the control of Grade Ⅳ.2. The target zone of Lamadian oilfield has separability as Sabei oilfield, which can be divided into the small layers of SⅡ15+16a and SⅡ15+16b. Because the study area is affected by many kinds of factors, the formation has the characteristics that the formation in the west is nuch thicker than that in the north.3. Based on stratum thickness graphs analysis,sedimentary sand mainly concentrated in the central and weatern, while sand in the east is much thinner. It is markedly divisional in the plane, established the typical models of stratum correlation in different background.4. According to lithology and mineral characteristics, shale color, sedimentary structure and fossils characteristics, it was divided into eleven types microfacies of delta plain and delta front. There are only eight types microfacies in research layers, respectively is distributary channel, ribeira fold deposits, abandoned channel, levee, crevasse channel, crevasse splay, flood plain and channel overspill deposition. According to the characteristic of logging curve, a log facies template is eatablished.5. Based on sedimentary microfacies of longitudinal evolutionary in single well and profile of several wells, in combination with regional geological and the distribution planar graph of sand content and seismic attribute map to find out that sedimentary microfacies evolution laws in three-dimensional space. The study represents that there are many directions of source branches. The main source is from the north. The main distributary channels are expended by strip, while some small distributary channels are expended by reticulation, formed a complex deposition pattern. The main sedimentary reservoir types are distributary channel sand and ribeira fold deposits sand.6. One of the most importment key is recognition of a single distributary channel on fine description of reservoir in the later period of the development. According to the well material, combined with depositional model, which can identify a single distributary channel by the patterns and rhythm of logging and sedimentary microfacies conbination and development dynamic materica. The seismic attribute is the embodiment of the homogeneous, when it is strong heterogeneity, it is clearly reflected the outline and continuity of sand in small layer by seismic attribute; it is easily to find out the sand of outlook and the level of the distribution, which is the most function on recognition of a single distributary channel. Comprehensive analysis of wells data and seismic data, which can effectively enhance the accuracy and precision on recognition of a single distributary channel.