| Tarim Basin is a typical large superposition basin with abundant Marine carbonate rocks.Due to frequent tectonic activities within the Tarim Basin,several large paleo-uplifts have developed in the northern Tarim Basin,Tazhong Tarim Basin,Tatong Tarim Basin and Keping ‐ Bachu area.Along the margins of the palaeo-uplifts,an important reservoir group of oil and gas resources--the eastern platform margin reef-flat sedimentary system is distributed.It is the largest carbonate platform margin exploration field that has not been broken through yet.Reefbank reservoir development conditions are good,Lunnan,Gucheng,Tazhong in the Cambrian and Ordovician reef-bank breakthroughs.However,due to various factors,the basic understanding of the eastern platform margin zone is not in place,the potential of the eastern platform margin zone is not clear,and the exploration direction is not clear,which restricts the further exploration of the eastern platform margin zone.Through the investigation of previous research results,it is found that the most important problem at present is that the spatio-temporal model of the Cambrian-Ordovician sequence and the sedimentary transformation are not clear,which cannot guide the evaluation of reservoercover assemblages.Therefore,in view of the above problems,this study aims to accurately depict the migration and distribution rules of reefs and shoals in different periods through the earthquake and previous research results,and establish a fine sequence framework.The restoration of the Cambian-Ordovician sedimentary evolution model in the eastern platform margin provides an important basis for the study of favorable exploration zones and traps.The specific approach is to integrate and match the results of previous studies such as comprehensive logging,drilling coring and outcrop with the earthquake,determine the sequence interface through single well calibration and connecting well comparison,and analyze the seismic phase of the earthquake.The two methods are combined to make plane prediction of the reef beach in the eastern platform margin zone,and make clear the lateral migration and distribution law of the reef body in each phase and the longitudinal growth law.At the same time,the main controlling factors of platform margin sedimentary facies were analyzed by integrating palaeogeomorphology,thickness map,attribute and seismic equality,and the plane distribution characteristics of platform margin sedimentary facies were described to establish a new depositional model of platform margin zone,and the favorable areas of eastern platform margin zone were predicted by integrating source,reservoir,cap and fault.The typical seismic reflection structure of the reef at the edge of the platform is hummock-like or lenticular shape,and the internal reflection is discontinuous,chaotic or blank.The particle beach is mainly characterized by medium-weak amplitude medium-weak continuous forward product reflection.Based on the previous research results and seismic data,the division patterns of 11 third-order sequences of the Cambrian platform margin belt in Lunnan-Fuman area are established.It is considered that the platform margin belt has experienced the sedimentary evolution process of gentle slope,weak edge,strong edge and gentle slope.The platform margin zone continued transgression in the early stage,and the platform margin gradually rose higher and steeper,reaching the highest point in the Middle Cambrian.At the end of Middle Cambrian,large-scale regressions occurred,forming low deposits,and then rapid transgression,depositing SQ7 and SQ8 in high areas.In the late Cambrian,the sea level dropped again and low beach developed.Based on the combination of source and reservoir configuration and preservation conditions,it is pointed out that there are five favorable exploration areas in the platform margin zone,namely SQ3 cloud bank,SQ6 reformed reservoir,SQ8 inner bank,SQ8 mound bank and SQ11 mound bank. |
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