High-resolution 3D Seismic Prediction For Thin Reservoir

With the increasing demand for oil and gas exploration area,continue to extend the area of more complex.Complex surface typically involves complex underground structure.The main problem of complex surface seismic exploration is to bring the ratio,complex surface structure,the complexity of seismic wave field,velocity model for complex structure imaging is difficult,low SNR,and the current exploration area is no longer simple structureexploration,even the structural reservoir,its structure is more complex,for the small fault block,overthrust nappe,high and steep structure,salt tectonics.Exploration of stratigraphic and lithologic oil and gas reservoirs is an important issue that we are facing,"more and more low,deep exploration,thin,hidden,difficult" more prominent,the exploration is more and more big,the exploration precision is higher.Therefore,in the face of the complexsurface and underground geological conditions,as well as the requirements of higher precision,seismic exploration technology must be committed to improve the signal to noise ratio,resolution and fidelity.To do this,the urgent need for a more optimum theory and method for complex structure and lithology exploration and provide a reliable basis,and can further improve the reservoir and hydrocarbon prediction accuracy.This paper in recent years in the oil and gas fields in the study of reservoir prediction based on high resolution seismic processing principle,method,technology and reservoir inversion and prediction and its application effect,according to the particularity of the continental basin,the comprehensive application of high resolution seismic,geologic,drilling,logging,oil testing and other information high resolution seismic inversion and reservoir prediction and hydrocarbon detection and other aspects of research,to explore a set of suitable for the thin interbeds of sandstone and mudstone geological conditions,system of technical method is feasible and can predict the reservoir of oil and gas,so as to achieve the purpose of improving the precision of reservoir prediction.In this paper,an example of Sulige gas field,for small thickness of the Sulige gas field,reservoir,complex superimposed model of sand body,the sedimentary environment changes lead to distribution of single sand body formed in the layer of large,vertically in the reservoir is thin,more scattered,miscellaneous "plane" characteristics superposition continuity,on the basis of high resolution seismic processing method research,carried out the research of thin layer of fine prediction method.Through the unremitting research in recent years,formed a set of the clastic rock of thin reservoir prediction technology series,the real drilling results show that after applying to other exploration area has good exploration result.The main results are as follows:1,to carry out a series of research work to improve the method of processing technology,the resolution of seismic data interpretationHigh resolution processing to improve the resolution,involving many aspects of work.Processing technology to improve the resolution of seismic data is still the deconvolution technique.For the study of AVO technology on the amplitude prestack gathers relatively put forward very high requirements,therefore,both in the pre stack and post stack,can only choose to play with deconvolution method relative amplitude preserving.Poststack spectrum whitening,minimum entropy,maximum entropy deconvolution method because of the characteristics of multi function mapping,relative amplitude preservation can not achieve space.We choose the surface consistent deconvolution,predictive deconvolution,due to its characteristics of single function mapping,which can not only realize the relative amplitude preservation,and can achieve the purpose of improving resolution.The prestack time migration section,the apparent resolution it explanation for the subsequent construction is necessary in the post stack increasing,whitening,select the post stack spectral tuning deconvolution method for treatment.Through repeated tests by tuning deconvolution and spectrum broadband processing technology to poststack high resolution processing final.Application of high resolution seismic data processing technology,the resolution of seismic data has been greatly improved,,through prestack,poststack high resolution processing,improve the resolution of the original data,effectively widening the band from 10-60 Hz to 10-80 Hz,the high frequency effectively recovered.To provide reliable data for fine interpretation of reservoir prediction.High resolution seismic interpretation,using high resolution 3D interpretation method,and small range of fine structure mapping technology,respectively from the macro geological interpretation and geological interpretation of small combination method,from the point of surface binding to three-dimensional space combination.Make full use of the high resolution seismic events,characteristics of high resolution capability,structure fine then,play the advantages of the high resolution seismic data.2,research to improve the resolution of reservoir inversion technique,analyzed its application conditionsThe seismic inversion technology is the core technology in reservoir prediction.The seismic inversion algorithm is recursive algorithm,genetic algorithm,greedy algorithm,simulated annealing algorithm,stochastic hill-climbing algorithm and other algorithms,through a variety of comparative and ultimately determine a cost-effective,efficient algorithm as the main algorithm of seismic inversion process.Spatial variation of reservoir characteristics,the initial model is given to improve the calculation speed of the inversion process,but also can improve the inversion precision under certain constraints.Study on the method of building the initial model,through the optimization of the initial model,to improve the inversion precision problem.Also by external input initial model.At present,most of the inversion algorithm of low resolution,or it is difficult to adapt to the formation of strong heterogeneity,how to make the results of seismic inversion has high resolution and is suitable for the strong heterogeneity of reservoir prediction is one of the key demand of the study area,through the analysis of application condition of each algorithm,we use the stochastic seismic inversion method can meet the needs of to obtain the ideal,and in the actual application effect.Stochastic seismic inversion is based on statistical characteristics of parameters as a constraint inversion technique,the lithological inversion,stochastic disturbance is directly lithology parameters,based on the wave impedance between rock and the wave impedance of the conditional probability density functions of sampling,investigation of synthetic seismic record and a correlation between the actual earthquake records,if the correlation increases.Think rock disturbance is effective,until the synthetic and real seismic records related to a given objective function.Others think that inversion process is finished.3,research on the technology of comprehensive reservoir parameters interpretation of high resolution dataPrediction for lithologic gas reservoir,reservoir space must first of the reservoir,the spatial distribution characteristics of sandstone reservoir prediction.In fine horizon calibration based on the reservoir characteristics of seismic waveform analysis,study its seismic response model;application analysis,3D seismic attribute reflection characteristics of qualitative research method,the spatial distribution of reservoir characteristics.Based on the favorable sedimentary facies belt prediction results,through the multi well constrained inversion of poststack random sandstone reservoir quantitative prediction.Prediction method is mainly reflected by the qualitative and quantitative prediction of sandstone,the zone prediction of prediction of sandstone prediction of gas effective sandstone such a gradually deepening process.On the basis of reservoir calibration,on the reflection waveform,near the reservoir wave group characteristics(including the reflection wave shape,geometry and internal reflection structure)are analyzed,based on the analysis of the forward and the model of reservoir sedimentary facies,lithological characteristics,summed up the different types of reservoirs.Different seismic waveform characteristics of gas reservoir and the corresponding layer of typical wells,a reservoir(especially gas bearing sandstone)model of seismic response.The 3D seismic attribute analysis can objectively reflect the characteristics of reservoir and sedimentary drilling calibration phase,after analysis,this difference reflects the heterogeneity of the reservoir in a certain extent,reflects the distribution of river development zone.The seismic attributes analysis the main idea is to 3D data from large,rich,pick up the hidden in these data related to lithology and reservoir information,and eliminate the data distortion,and then through the small hole reservoir characteristics as a communication bridge,seismic attributes and reservoir,so as to reveal the the distribution of reservoir characteristics,enhance the application of seismic data in the exploration and development of oilfield.4,in-depth study of the gas water of the study area of the vertical and horizontal distributionThe actual formation,most of rock containing pore,pore is also contained in the fluid,especially the density of the fluid reservoir is the economic significance of the various liquid substances contained in the pore space of reservoir density effect.In general,the pure gas density is less than 0.2g/cm3 in the pores of the rock,fluid density from the rich gas to water,amplitude variation is very obvious.Using logging data from wells,reservoir fluid density values on through some calculation method,and then according to the well fluid density and 3D seismic data inversion,3D data of fluid density body,used for the qualitative and quantitative analysis of reservoir fluid,directly determine the gas reservoir.The method of seismic data with high signal-to-noise ratio,density logging data is true and reliable,to choose a gas water relations representative significance in the research work of the well data as learning samples.Application of this method can be roughly separated water area and the natural gas enrichment area in the study area,and the drilling of the coincidence rate is 75%.The use of array acoustic logging data to calculate the Poisson's ratio of single wells,combined with 3-D seismic data using neural network algorithm to obtain the Poisson space than the inversion information,then according to the research work of Poisson's ratio and gas water relationship to study the distribution of gas and water.This method requires a certain amount of array acoustic logging data in the research area of Poisson's ratio,and the relation between gas and water and on the basis of array acoustic wave data to calculate has a good corresponding relationship.In this study the prediction results with the actual drilling results coincidence rate reached 78%.