| Fanxue-Wangpan Mountain Block is located in Fanxue Township,Wangpanshan,Dingbian County,Shaanxi Province,and its tectonic location is on the western edge of the Yishan slope of the Ordos Basin.The terrain is high in the east and low in the west.The area has now entered a phase of comprehensive development and has achieved many significant results in the exploration of the Jurassic and Triassic strata.In order to continue to increase storage and production,continue to deepen exploration,find reserve replacement areas,continue production advantages,make use of logging data obtained from exploration,and conduct comprehensive and systematic investigations on the Chang 2 reservoir in light of scientific research results at the present stage.The characteristics of its stratigraphic features,sedimentary environment,distribution rules of sand bodies,reservoir characteristics,and reservoir accumulation patterns were clarified to provide a theoretical basis for actual production.First,a fine stratigraphic framework was established through high-resolution sequence stratigraphy research methods.Through the observation of a large number of logging curves,the distinctive K9 mark layer was identified as the top 2 mark.Then,12 skeleton profiles were established to form a profile network and to achieve the closure of the entire region.Finally,log adjustment characteristics of some wel s were used to adjust,and the long 2 segments were finely divided into length 213,length 212,length 211,and length 221.222 long,23 small layers.By analyzing the distribution of heavy minerals and detrital minerals in the study area and the variation of sand body thickness,it is concluded that the source of the study area is mainly the Archean metamorphic rock from the northeast.Based on this conclusion,the deposition pattern of the study area was analyzed.By identifying sedimentary facies marks such as rock color,grain size,structure,and well logging characteristics,it was concluded that the entire study area is in the delta plain subfacies.The main microfacies consist of underwater distributary channels,diversion-level depressions,natural dikes,crevasse fans,and spot sands.Dam and so on.Then,through the analysis of profile and plane sedimentary facies,the deposition pattern of the study area was comprehensively and three-dimensionally analyzed.Through the study of the "quaternity" relationship of reservoirs,it has been found that the lithology of the reservoir is mainly light gray medium-fine,extremely fine-grained lithic feldspathic sandstone.The porosity,permeability and oil saturation of the reservoir are basically the same as the trend of the peaks.The reservoir type in the study area is a lithologic tectonic reservoir and there are well-developed sets of reservoirs.The oil source comes from the source rock of the 7th section of Changchang River.The sand body of the channel constitutes a good reservoir,and the mudstone in the diversion can form a good shelter.These favorable conditions combined with the mechanical compaction,cementation,and erosion of the study area produced a good reservoir.After clarifying the model of reservoir accumulation in the study area,the relevant knowledge of petroleum geology was fully utilized,combined with the characteristics of regional sedimentary structures,and favorable reservoir-forming areas were identified in each sub-layer through reservoir profile analysis.Based on this,it provides an important reference for the deployment of production. |
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