Hydrocarbon Concentration Regulars And Exploration Techniques Study For Jiyang Depression Stratigraphic Reservoir

It is known that the structure reservoirs,the lithologic reservoirs and thestratigraphic traps grew at continental basins.In the past forties years there were tworespectively structure reservoir and lithologic reservoir which were representative oftwo exploration peaks,among which the stratigraphic traps were found sometimes,and the stratigraphic traps were subtler,more complex formation and more difficultexploration than other two reservoirs.In the earlier exploration the stratigraphic trapswere drilled unsuccessfully because of its unclear forming regulars and lack ofeffective exploration techniques.In recently the reservoiring regulars and explorationtechniques havebeing studied systematically in the help of studying a set oftechniques in the research for stratigraphic traps.The main works are:(1) Collectingabroad and home study results in the research for stratigraphic traps to understand thestudying present and developing trending for finding stratigraphic traps;(2)Processingseismic aiming at finding stratigraphic traps in the ways of high resolution process,pre-time migration and pre-seismic inversion process,the total area in the processedseismic data was over 1500km~2,the data interpretation area was over 20000km,400structures maps and analysis maps were completed;(3)The different types of reservoirmodels were built through analyzing 9 structure zones (oil fields) to provide oilenriched regulars concentrated at stratigraphic traps;(4)Variable techniques predictedthe traps were studied to form a serial of techniques to evaluate synthetically thestratigraphic traps.As a result of study three new techniques had been developed.They are asfollow.1.Three orders unconformities by which stratigraphic traps were configured areprovided and five reservoir models are built.The distribution rules for stratigraphic onlap with three orders unconformitiesand traps with unconformities barriers are provided to build five trapping models toshow the oil enrichment regulars for stratigraphic traps.They are considered as onlap traps formed at Upper Tertiary that the traps are"growing in sags and steep slopes andonlap flutings,migrating vertically firstly and horizontally secondly for long distance,sealing by stratigraphic and shale and heavy oil,controlled by palaeogeomorphology."They are considered as barriers traps formed at Upper Tertiary,which are"growing insags and gentle slopes and low bulges,contacted diagonally with Down Tertiary at NgGroup,migrating upper along the horizons,sealed by heavy ail and shale."Those areconsidered as subcrop traps formed at ante-Tertiary,which are"growing at subcropwhich uplifted source rocks,its physical property are better in fracture or Karst,oilmigrating in multi-way,it is important to find nose-structure background."There aretwo levels trapping models within source rocks,they are"traps with shale overlaidsand which configured within oil rocks,sandstone and mudstone had poor pressuredischarged,the hydrocarbon filled into fracture driven by pressure discharged,trapswith shale overlaid sand which configured at the margin at box,"and there are alsotwo orders trapping models outside source rocks,which are"structural nose at slopein subsag,they were configured either upper or down of beach and bar or low delta,the oil migrates through faulted-sand".2.Three methods and two approaches are created to be used to describetruncation edge of stratigraphic trapsThe three methods,which are geostatistics,angle extrapolation and propertyprocess,are developed to describe stratigraphic truncation line,the depositionalpinchout is described by waveforms analysis and prestack inversion to predictstratigraphic traps quantitatively.3 Six steps processes built to evaluate comprehensively stratigraphic trap.The six steps are:building sequence framework in high resolution,dividingdifferent study zone by structure analyzing,defining targets by different orderunconformity,finding pool at deposit zone,describing trap by composite"three lines",analyzing interesting targets,which can be used to evaluated different typicalstratigraphic trap to deploy drilling sites.The methods,such as strata onlap or denudation interface description,reservoirdescription and"six steps"approach,are developed to quantify strata traps to recognize the strata traps property,by which the traps grew at Zhanche area,Dongying sag and Chengdao area are studied and their trapping conditions and oilenrichment regulars are summed.As a result we have got breakthroughs andimprovements in oil fields of Chenjiazhuang,Taiping,Wangzhuang-Ninghai,Linfanjia,Gaoqing,Shanjiashi,Bamianhe,east slope of Chengdao and north slope ofChengdao.Interesting trap area is predicted to be 311.8km~2,original oil and gasreserves is predicted to be 152.4×10~4t.The better economic benefit has bee got.