Thesis/Dissertation Guide For Postgraduates Of Northwest University

A large number of researchs have been carried out on the sag structures,regional structures,faults and local structures of zhanhua sag(including Chezhen Sag),which is an extremely important petrolifeous sag in eastern China.However,less attention has been paid to the low-high structural pattern,the relationship between low-high structure and the faults,and structures related to faults,which are closely related to Oil&Gas reservoirs.Based on that,the low-high structural pattern and its evolution,and the structures related to faults and its evolution have been analyzed in this paper,on the basis of the seismic structures of T6(Es3z),T2(Es1)and T1(Ng)in Zhanhua Sag,combined with 3D seismic and other datas.Furthermore,the characteristics of Hydrocarbons migration and accumulation have been initially analyzed.The main conclusion are as follows:(1)Dviding of low-high structural pattern.According to the synthetic relation between slot line(the connection between the lowest point of tectonic and its relatively lowest point)and long line(the connection between the highest point of tectonic and its relatively highest point),The low-high structural pattern of the source rock in zhanhua sag(including Chezhen Sag)were divided into six concave-silom areas:around Chengzikou concave-silom area,around Yihezhuang concave-silom area,around Gudao concave-silom area,around Gunan concave-silom area,around Zhuangxi concave-silom area and around Chengbei concave-silom area.Furthermore,each concave-silom area could be further divided into concave-silom bands based on valley line(the connection between the relatively lowest point,and it located between the slot line and long line)and ridge line(the connection between the relatively highest point,and it located between the slot line and long line).There are three main categories divided by its shape:Dustpan,Fan-shaped and Half ring concave,among them the dustpan is the main type.(2)Rlationship between fault and low-high structural pattern.According to the relationship between fault direction and tectonic contour,the faults could be divied into two types:along-slope fault and cut-slope fault.Along-slope fault Refers to the faultwhich perpendicular to the tectonic contour,and cut-slope fault Refers to the fault which parallel to the tectonic contour.Both of the two types of faults are developed in zhanhua sag(including Chezhen Sag).(3)Main faults and its related structures.The section structure of fault,the relationship between fault and strata on both sides,fault-related local construction,and the fault activity of the main faults have been analyzed,these faults include Caojiazhuang fault,Da71 fault,Gubei fault,Gunan fault,Guxi fault,No1 fault,and No2 fault.The results indicate that the relationship between fault and strata on both sides is mainly composed of the same half-ridge half-trough.Fault-related local construction is mainly monoclinic structure.All faults are continuous active faults except No1 and No2 faults.(4)Characteristics of hydrocarbon accumulation in low-high structural pattern.The low-high structural pattern of source rock(concave-si lom bands)is the fundamental unit of formation and distribution of oil field.In the same concave-silom bands,oil and gas have a trend migrate from the low point of structure to the high point of structure in a whole,and the high part of slot line and the ridge line are convergence direction of oil and gas.Oil and gas reservoirs could be formed in the area between the slot line and the long line.If faults develop in the concave-silom bands,it can partial adjustment the direction of oil and gas migration,and form Oil and gas reservoirs beside the fault,such as Dongfenggang oil field which locates around the north of Caojiazhuang faults and nearby the slot line.In the overlying strata of the source rock,the direction of oil and gas migration is mainly related to fault.In the case of oil and gas input at the lower end of the fault,the hydrocarbon migration is main moving along the fault(moving along the structural form low to high).After moving to the top of the fault,it can continue moved from the lower point to the high point,and then migrated from the fault to both sides of the fault,thus oil and gas enriched in the fault-related structure.Oil&Gas field of EsZ and Esi main located nearby the fault,such as Futai oil field,Dawangbei oil field,Dawangzhuang oil field,and Luojia oil field.etc.Those oil field distributed in the low part of concave-silom bands(around slot line),the high part of structure(around long line),and the slope.Oil&Gas field of Ed,Ng and Nm also located nearby the fault,such as Yihezhuang oil field,Gudao oil field,Chengdao oil field,Laohekou oil field,and Feiyantan oil field.etc.Those oil field also distributed in the low part of concave-silom bands(around slot line),the high part of' structure(around long line),and the slope.(5)Suggestions for Exploration.According to the above mentioned relationship between low-high structural pattern and hydrocarbon accumulation,in the dividied nineteen concave-silom bands,it can be implied that oil&gas field can form between the slot line and long line.However,oil&gas field are found between the slot line and long line in only individual concave-silom bands.Therefore,more attention should be paid to the the low-high structural pattern where oil&gas field are not found.In the overlying strata of the source rockK hydrocarbon can accumulation in the fault related structures.Therefore,it is necessary to strengthen the oil and gas exploration in the low parts of fault related structures.