Research On Reservoir Characteristics And Application Of Prediction Technology In The Northern Kendong Area, Shengli Oilfield

There are abundant hydrocarbon resources in the beach area of Shengli oilfield,and the oil reservoir of the Kendong area has been regarded as one of the mostimportant exploration targets. It also shows that the gas reservoir is controlled by twofactors of lithology and structure; the traps are mainly stratigraphic traps. The maintrap types of the Northern Area of Kendong include fault block hill trap and residualhill trap in Pre-tertiary, stratigraphic overlap trap and lithologic trap in lower Tertiary,and lithologic-structural trap in Neogene. There are the lithologic reservoirscontrolled by lithologic updip pinch out in the northern slope belt and the lower partof the structure. The lithologic-fault nose reservoir developed in the eastern fault zone,where the fluvial facies sandstone is dissected by antithetic faults. The target layersare characterized by shallow burial depth, thin sandbody, and lithology variesdramatically in both lateral and vertical directions. Additionally, oil-water relation ofthe reservoir is complicated and the seismic data are full of multiplicity, which makesit very difficult to predict the reservoirs.Aiming at the structural-lithologic reservoirs with complex geologic structure, thesystematic study was performed on the reservoir-forming law and explorationtechnology. On the basis of the deep study on the reservoir-forming law, reservoirprediction and trap evaluation, the favorable exploration targets are proposed.According to the fault dip&azimuth changes, the coherence analysis techniquewas used to enhance linear and planar features and the noise was reduced by thefiltering proceeding. On the basis of optimization of the vertical and horizontalvectors, the3-D fracture system was obtained with3-D visualization technology.For the objective interval of the study area has well developed faults and biglateral variation of velocity, the variable velocity mapping was applied for theprediction. Based on the interval velocity, formation dip and spatial offset ofreflection point deflecting incident point by the model chromatography, which isconstrained by drilling, logging and seismic interpreting horizons, the accuratestructural map was obtained. By contrast with the structural map of the traditional method, it could be used to identify low amplitude structure.Based on the synthetic analysis and study on the geology data, seismic data andlogging data, the study on seismic prediction techniques were made. By using thetime-frequency analysis, neural networks and waveform analysis technique, thesedimentary facies were divided into channel, embankment, flood plain andabandoned channel subfacies. The constrained sparse spike inversion was used inreservoir characters inversion and the impedance data volume obtained fromconstrained sparse spike inversion were used for prediction. From the inversionresults, the space distribution of14sets of oil-bearing sand were marked. By contrastwith the drilling well, the prediction accuracy is more than80%.By using the forward modeling, the seismic response characteristics of the channelsand body was described. The medium-high frequency (40～60Hz）of the seismicdata can reflect the thin sandstones.A variety of seismic attribute analysis and test ofmultiple seismic attribute parameters were maded, combined with the drilling result,the sensitivity attributes were determind which can be used to identify the thinsandbones.In this paper, integrated by the geophysical characteristics of rocks in Tertiary, theinfluence of the variations of the lithofacies, lithology, physical property and fluid onthe seismic response in the research area is analyzed. The study on the reservoirprediction technology of the fluvial facies sandstone in Neogene is carried out, andthe identification technology series of the lithology, physical property and fluid of thereservoir have been created.As a result of study three new techniques had been developed. They are asfollowing：①the developed technology for identifying complex fault system in the northernarea of KendongThe automatic faults identification technology is applied to the comprehensivestudy on the horizons, which is one of the advanced faults identification technology.By using the automatic faults identification technology, the plane distributionregularity and complicated association of faults can be viewed straightforwardly.②the developed technique for identifying correctly thin sandstones in the beacharea of KendongThe study on the reservoir identification technology of the thin sand bodies of braided river facies was made. By using the frequency expanding processing, spectraldecomposition and constrained sparse spike inversion technique, the faultsdistribution and pinchout boundary of the thin sandstones can be described correctly.③the reservoir characters inversion for the thin sandstones in the beach area ofKendongThe velocity difference between sandstone and mudstone is so weak that theacoustic curve can not demonstrate the lithologic characteristic of the strata effectively.Therefore, the reservoir characters log obained from well log which can showlithologic characteristic effectively, can be used for reservoir characters inversion.