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

It is known that the structure reservoirs,the lithologic reservoirs and the stratigraphic trapsgrew at continental basins.In the past forties years there were two respectively structurereservoir and lithologic reservoir which were representative of two exploration peaks,amongwhich the stratigraphic traps were found sometimes,and the stratigraphic traps were subtler,more complex formation and more difficult exploration than other two reservoirs.In theearlier exploration the stratigraphic traps were drilled unsuccessfully because of its unclearforming regulars and lack effective exploration techniques.In recently the reservoiringregulars and exploration techniques have being studied systematically in the help of studying aset of techniques in the research for stratigraphic traps.The main works are:(1) collectingabroad and home study result in the research for stratigraphic traps to understand the studyingpresent and developing trending for finding stratigraphic traps,(2)processing seismic aiming atfinding stratigraphic traps in the ways of high resolution process,pre-time migration andpre-seismic inversion process,the total area in the processed seismic data was 1500km2,thedata interpretation area was余层km,400 structures maps and analysis maps were completed,(3)the different types of reservoir models were built through analyzing 9 structure zones (oilfields) to provide oil enriched regulars concentrated at stratigraphic traps,(4)variabletechniques predicted the traps were studied to form a serial of techniques to evaluatesynthetically the stratigraphic traps.As a result of study three new techniques had been developed.They are as follow.1.Three orders unconformities by which stratigraphic traps were configured are providedand five reservoir models are built.The distribution rules for stratigraphic onlap with three orders unconformities and trapswith unconformities barriers are provided to build five trapping models to show the oilenrichment regulars for stratigraphic traps.They are considered as onlap traps formed atUpper Tertiary that the traps are"growing in sags and steep slopes and onlap flutings,migrating vertically firstly and horizontally secondly for long distance,sealing by stratigraphicand shale and heavy oil,controlled by palaeogeomorphology."They are considered as barrierstraps formed at Upper Tertiary,which are"growing in sags and gentle slopes and low bulges,contacted diagonally with Down Tertiary at Guantao Group,migrating upper along the horizons,sealed by heavy ail and shale."Those are considered as subcrop traps formed atante-Tertiary,which are"growing at subcrop which uplifted source rocks,its physicalproperty are better in fracture or Karst,oil migrating in multi-way,it is important to findnose-structure backgroud."There are two levels trapping models within source rocks,they are"traps with shale overlaid sand which configured within oil rocks,sandstone and mudstonehad poor pressure discharged,the hydrocarbon filled into fracture driven by pressuredischarged,traps with shale overlaid sand which configured at the margin at box,"and thereare also two orders trapping models outside source rocks,which are"structural nose at slop insmall sag,they were configured either upper or down of beach and bar or low delta,the oilmigrates through faulted-sand".2.Three methods and two approaches are created to be used to describe truncation edgeof stratigraphic trapsThe three methods,which are geostatistics,angle extrapolation and property process,aredeveloped to describe stratigraphic truncation line,the depositional pinchout is described bywaveforms analysis and prestack inversion to predict stratigraphic traps quantitatively.3 Six steps processes built to evaluate comprehensively stratigraphic trap.The six steps are:building sequence framework in high resolution,dividing differentstudy zone by structure analyzing,defining targets by different order unconformity,findingpool at deposit zone,describing trap by composite"three lines",analyzing interesting targets,which can be used to evaluated different typical stratigraphic 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 thestrata traps property,by which the traps grew at Zhanche area,Dongying sag and Chengdaoarea are studied and their trapping conditions and oil enrichment regulars are summed.As aresult we have got breakthroughs and improvements in oil fields of Chenjiazhuang,Taiping,Wangzhuang-Nihai,Linfanjia,Graoqing,Shanjiashi,Bamianhe,east slop of Chengdao andnorth slop of Chengdao.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.