High Resolution Sequence Stratigraphy And Hydrocarbon Accumulation Model Of Putaohua Oil Layer In The East Of Sanzhao Depression

Songliao Basin, a continental basin with rich oil and gas resources, with the deepening exploration and development, is facing the severe problems including reserves and declining in production, however, the east of Sanzhao depression Putaohua reservoir is connected to the oil and gas resources in Songliao Basin. Thus, the study on high resolution sequence stratigraphy and sedimentary facies in the east of Sanzhao depression and the summarizing of the area of oil and gas accumulation and favorable oil and gas rich region, both of which provide a theoretical basis for the further oil and gas exploration development in the area.The thesis, based on the high-resolution sequence stratigraphy and its technical methods as well as the use of detailed core data, seismic data and drilling data of mature exploration area, through Dynamic Analysis on all levels of the sedimentary base level cycle times and different grades of identification of base-level cycles interface, takes the east of Sanzhao depression Putaohua as the research object, and the comprehensive study of cross-Depression Placanticline～Zhaozhou top and bottom of the well profile standard layer control, fine contrast, color and mudstone microfacies core vertical sequence, the plane microfacies evolution sequence, corresponding analysis of adjacent areas, indicates that the east of Sanzhao depression Putaohua oil layer can identify two medium-term base level cycles, and nine short-term base level cycles. On the basis of the analysis of the structural type of short term base level cycles sequence, research district Putaohua oil layer is proposed that:"south stratigraphic thinning, the top of the Putaohua oil layer move up, the end move down, each layer gradually thinning, The transition point of the medium term base level cycle is located the center of SSC₄,there is a decreased half-cycle under the transition point,and a increased half-cycle above the transition point" development pattern formation, and a high resolution sequence stratigraphic framework is established,which unified study area with the Sanzhao depression.In the fine control of isochronous stratigraphic framework to analyze the source, depositional systems and sedimentary facies distribution characteristics, the thesis proposed that the Putaohua oil layer of the study area is a typical mainly controled by northeastern source"large river-dominated shallow delta sedimentary system", and the dense well in development zone reveals that: delta front facies, and " a large number of dense, narrow underwater channel sediments, the former, the lateral margin of sand into a thin layer "of the river -controlled strip of sand mode, so that the outer south-central front is not the original sand layer, but extending far south river water to form a high-quality reservoirs in the extended south. The skeleton of sand body is in a large number of narrow banded shape (mostly 200 300 m), and can extend hundreds of kilometers of continuous, dense, overall was SW, and combines well with other types sand surface to become a better distributary channel sand body. Based on in-depth understanding of the background of the east of Sanzhao depression Putaohua deposition, sedimentary characteristics and facies types, we established river-controlled Putaohua shallow delta depositional model, and further broken down into five sedimentary facies model, namely: delta distributary plain, the "river-controlled belt body" model, delta front-distributary plain transition zone "offshore" model, delta front area in front "River-controlled belt body" model, the delta front - outside the front transitional zone "controlled underwater distributary channel and the end river controlled sheet like sand "model and delta front area outside the front" waves controlled sheet like sand" mode.Based on the study of the regulations of isochronic stratigraphic framework and spatial distribution of single sand bodies, take full use of oil and gas accumulation system and new ideas of modern oil and gas geology, apply the technology of comprehensive analysis of accumulation region, a single sand body oil control mode analysis and techniques such as forecasting of complexity oil block, etc. Through the analysis of discovered reservoir types and distribution system, the thesis points out that fault-lithologic reservoir oil and gas accumulation is controlled by four kinds of geological factors:â‘ The oil and gas origin and the definition of reservoir formation period are the first essential;â‘¡The palaeostructure evolution and the field of oil and gas migration and accumulation have important control action for the oil/gas migration and accumulation reservoir formation hydrocarbon migration and accumulation.â‘¢The distribution of (submerged) distributary channel sandbodies control spatial distribution of quality reservoir, quality reservoir formed by channel sandbodies accounted for more than 85%;â‘£The fault dominates the hydrocarbon migration and accumulation, fault and the array mode of sand body controls the hydrocarbon migration area and distribution. What's more ,the oiliness is lower. Tibetan rock type proposed three levels of oil forming rules:â‘ the first one forming rules for the regional level, a characteristic that "principal component oil control, multi-coupled enrichment", revealing the overall oil and gas accumulation zone;â‘¡the second rule for the three-level structure forming rules, a "three-tier structure controlled potential, controlled possession of a single trap" features, the interpretation of the local water distribution;â‘¢the third rule for a single trap with a "local control of community structure, a single layer of sand control" feature, clear profile of a single trap accumulation controlling mechanism. This is the way proposed: oil and gas area was "one-way three-way accumulation mode": Old South is still found in the nose structure of hydrocarbon migration area was 'one-way three-way migration model', namely :Move along the axis of Shangjia nose structures, the axis of Shangnan nose-like structure, along Fengle slopeswith the three-way two-way migration style. Therefore, the ring concave area, the both sides of the main oil and gas migration routes are favorable oil and gas accumulation zones. Also put forward: in the critical period, the axis of Shangjia nose-like structure and the shift of Sanzhao depression center of oil and gas accumulation had a significant impact on hydrocarbon accumulation and oil and water distribution, favorable traps forecasts. The proposed law forming essentially reveals the internal complexity of lithological type of oil Tibetan distribution of oil and water, namely: extremely complex lithology water distribution of hydrocarbon reservoir is caused by an oil Vertical multi-layer, multi-branch single-plane and complex sand traps formed combination of local structures and non-trap superimposed in space. And that local structures, one of the distributary channel and the combination of the two spatial relations are extremely complex and opened the controlling factors of space and laws of water distribution bottlenecks, the next reservoir lithology class exploration and development has important practical applications value and significance.Under the guidance of the above results, based on the hydrocarbon accumulation rule of the reservoir levels 1, 2,the thesis predictives Shangnan nose-like structure, north wing of Shangjia nose-like structure and Fengle slopes which are favorable oil reservoir area; according to anatomy of dense well and sand and oil migration direction, the author believes that there are three kinds of accumulation mode: Yushulin area is the oil-controlled pattern of bearing down and moving up inside, shortness side migration, and fault-sand matching. Fengle area is the control oil pattern of bearing down, moving up and saving up in side, short lateral conveying, fault-sand matching, and structure. Fengle area adopts the mode that oil produced upward and stored upward, fault-sand matching, micro-magnitude oil- controlled structure. For Chaoyanggou area, the mode is accumulating outside the reservoir, backing up Fuyu oil layer-lateral migration-shift up Putaohua oil layer, sand body oil-controlled mode. And the author points out eight types of trap controlled models in dense well network area. And make recommendation that ten wells should be located.