Technology Research on Tertiary Reservoir Prediction in Jiyang Depression.pdf

1、The Tertiary stratum in Jiyang Depression is the chief series of exploration anddevelopment strata for Shengli Oilfield. The subtle oil&gas reservoirs have become thechief objects of exploration and development currently

2、 after the exploration anddevelopment of 40 years, and the reservoir prediction is the key of exploration anddevelopment for subtle reservoirs. According to statistical analysis in recent years, morethan 40％ drilling wel

3、ls failed in Shengli Oilfield have resulted from reservoir predictionproblems (reservoir not developed or ascertained), therefore the original seismic predictionof reservoir has failed to meet the actual needs. For this

4、reason, the seismic predictiontechniques of reservoir need deepening urgently in order to reduce the blindness inreservoir prediction effectively and the risk of exploration and development to improveprediction accuracy

5、of reservoir and drilling success rate. In this study, based on a series of targeted seismic forward models by using a largenumber of seismic and geological data that combined with the development characteristicsof Tert

6、iary reservoir in Jiyang Depression, the seismic response characteristics of theTertiary reservoirs were analyzed by studying the relationship between the seismic forwardmodels and seismic response. By ways of combining

7、further analysis and study for theconditions of seismic prediction and the adaptability of prediction techniques with the fourtypical category reservoirs in Jiyang Depression, an effective series of technologies ofexplor

8、ation and development is optimized and integrated, which got the following fourmajor innovations through the research: (1) In the basic research of reservoir prediction, the regulation of seismic responsefor the main re

9、servoir in Jiyang Depressions summarized and the three-degree seismicmodel based on the results of test in laboratory and mathematical simulation isestablished. ①For the thick reservoir which is greater than 1/4 wavelen

10、gth, its amplitude responsehas no relationship with the thickness of interlayer as well as reservoir itself and thereservoir structure. While the changes of petrophysical property and lithologicalcharacteristic are t

11、he main factors for the responses, which are the foundation ofpetrophyiscal property and fluid prediction for the reservoir using seismic attributes. ②For the transitionary reservoir whose thickness is between 1/8 and 1

12、/4 wavelength, the thickness of interlayer also has some influence except the petrophyiscal property and lithological characteristic. ③For the complex thin sand-shale interbed, the key factors of seismic responses are

13、the tuned thickness of reservoir, assembled structure of reservoir (the thickness of reservoir,interlayer and its structure) and the regulation for change of reservoir acoustic impedanceetc. ④Established the three-degre

14、e seismic response model of reservoir which includesthe brightness, scale and purity. The "brightness" means the relative acoustic impedance,the "scale" means the relative thickness of reservoir and the "purity" means li

15、thologicalcombination structure in certain thickness of reservoir. Directed by this model, combinedwith the practical characteristic of the Tertiary reservoir in Jiyang Depression, fourreservoir based on the seismic resp

16、onses were divided to settle the theoretical basic forstudying the seismic prediction of reservoir. (2) In the feasibility research of reservoir prediction with the seismic data, therequirement of reservoir prediction f

17、or seismic data is made definitely ①The noise immunity of seismic attributes rise while the thickness of sand body andacoustic impedance are great and the accuracy of reservoir prediction is correspondinglyhigh; convers

18、ely, the reservoir prediction has higher requirement for the quality of seismicdata. ②The noise immunity of seismic attributes rise while the resolution of seismic data isgreater, and the results of reservoir prediction

19、 are better; conversely, the reservoir predictionhas higher requirement for the quality of seismic data. ③The seismic cubes whose signal-noise ratios less than 2 are not suited for theresearch of reservoir prediction, t

20、hat is to say, the signal-noise ratio should be larger than 2for studying the geological problems(strata thickness, lithological characteristic andpetroliferous property) using the seismic attributes. (3) In the adaptab

21、ility research of the key technologies for reservoir prediction,the applicable conditions of the three key techniques for reservoir prediction are madedefinitely. ①For the seismic inversion technology, we emphasized the

22、 ambiguity and integrity ofinversion results, meanwhile, presented the evaluation discipline of "primality" and"average" for seismic inversion. The discipline of "primality" means the results of seismicinversion may appr

23、oach the highest resolution of field acquisition in some content, becausethe inversion results may not be reliable by only improving the seismic resolution whileneglecting the accuracy and scale restriction of seismic da

24、ta. The "average" means thatseismic inversion results are the average value of practical geological model which theaverage function is set as the window as the average value, for any seismic inversion hassome average eff

25、ect. ②Made full analysis of the adaptability of spectral decomposition, summarized theapplicable conditions and suitable range, presented the basic conditions of analysis thesedimentary cycle with seismic time-frequency

26、 characteristics and the "limit principle" inthe application of spectral decomposition technology so as to settle the foundation for thefurther application of time-frequency analysis. ③Carried out the optimization for t

27、he seismic attributes and pre-stack attributes, andused seismic attributes to optimize the sensitive parameter and made prediction to thecomplex beach bar sandbody and got good results. (4) As for the typical Tertiary r

28、eservoir of Jiyang Depression in Shengli Oilfield,the seismic prediction techniques are optimized and integrated, which present a seriesof suitable seismic prediction techniques for the four typical sand body of channel,

29、turbidite, beach bar and glutenite. This study results have been applied to various lithological reservoir exploration inKendong, Laohekou and Chepaizi areas, etc, and have given great to theexploration. Contrasting wit

30、h the known drilling wells, the prediction error of reservoirdepth is less than 5％, reservoir thickness is less than 10％, and the success rate ofprediction is greater than 70％. This study results has obvious geological e