| 其他摘要 | The eastern area of Chunliang is one of the early explored oilfiled in Shengli oil field, with the main productive layers of Es3 and Es4. The main productive layers have entered a period of high water-cut stage or ultrahigh wantercut stage .Only sporadic wells have been perforated at Es2, some of them produce oil;In recent years, many fault block oil reservoirs that are high production have been found by using 3-D seismics to proceed progressive exploration，and some of them produce oil 20-50 ton early , which show Es2 has bigger rolling exploration potential .Therefore, researching Es2 sedimentary system, finding out distribution rule of sandbody of Es2, analyzing the accumulation rules and oil-controlling factors, is of impotance and pratical to the maintenance of oilfield’s production.
Based on cores ,well logs and other dates, with the application of high-resolution sequence stratigraphy theory, fine strata division and comparison has been done, and the sequence stratigraphic framework of the region of interest has also been built. With the use of cores, logging, seismic and other data ,Sedimentary system of Es2 in work area has been analyzed , types of sedimentary facies ,sub-facies and three-dimensional spatial distribution have been divided, and the spreading rule of sandbody has also been estabished. With the use of 3-D seismics,drilling and other data, fine description of the structure of Es2 has been made, and structural features have been analyzed;with the application of petroleum system, combining with the research of sedimentary system, oil and gas accumulation mechanism has been analyzed; basing on above work ,hydrocarbon distribution rules of Es2 has been done,and favorable targets for progressive exploration has been provided.
With the guidance of new theory, using geology, well logs, seismicand other date, and throught the comprehensive study of the data, the following results and understanding are obtained:
1. Through systematic analysis of Es2 sequence stratigraphy in study area, Es2 has been divided into 2 third-order sequences,further divided into 10 four-order sequences. Sequence stratigraphic subdivision and correlation has been proceeded in more than 130 wells, and 8 comparison of profile has been done.
2. Taking four-order sequence as modules, stratigraphic isopach maps, isopach maps of sandstone, sandstone percentage maps, and sand/mud maps of 10 four-order sequences have been finished; combined with single sedimentary facies analysis, sedimentary facies distribution maps of all the sequences have been done.
3. It is concluded through sedimentation analysis that, there are two periods of delta deposition in Es2, which are different sclae and sedimentary characteristics,; delta front and predelta subfacies have been mainly developed in lower Es2，and upper Es2 has greatly developed delta plain and delta front subfacies.
4．A series of nearly east-west strike faults have been grown in work area，the strata， northern part of which is lower than south,is step-1ike.That the lineament is unanimous with faults，which makes it difficult to fome large scale of structural traps，is the main cause of poor enrichment of oil and gas in Es2．
5．Most of Es2 reservoir is formed by vertical migration of underlying Es3 reservoir to shallow fomation through faults，the main tyeps of which are nose-shaped，the high oil filling up degree and sufficient oil source produced a great exploration potential.
6.Faults are the most important factor controlling Es2 hydrocarbon accumulation，on the one hand，the early opened faults are communication channels to underlying oil layers;on the other hand,the effective traps in workarea are fomed by fault sealing，and the fault sealing capacity directly determines the effectiveness of a trap．
Based on above production，the exploration potential of Es2 reservoir in the eastern area of chunliang of dongying depression has been integrally evaluated，many favorable exploration targets have been obtained,especially structural - lithologic composite oil reservoirs are the next important direction of progressive exploration;at present,one exploration target which can be drilled and one favorable hidden reservoir exploration area have been advanced. |
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