Comprehensive Prediction Techniques Of Deep Carbonate Karstic Fractured-vuggy Reservoirs

Sinian dengying Formation in Sichuan basin has an ancient geological time and a burial depth of more than 5000 m.Recently,the high risk GS1 well in Sinian Dengying Fm has one million square,which opened a new chapter of Sinian Fm in Sichuan basion exploration,and being subjected to the world's attention.The fractured-vuggy reservoir features is same as the Ordovician carbonated reservoirs in Talimu basin,which has a deep burial depth,a strong heterogeneity.Sinian Fm affected by multiphase tectonic movement,Fracture system development,Carbonate reservoir development are controlled by many factors,such as the high karst degree,small fractured-vuggy scale,low matrix porosity(< 6%),diffichlt oil accumulation,strong lateral heterogeneity,large burial depth,low exploration degree,which cause a low prediction precision and uncertainty solutions,this complexity is rarely in similar reservoirs in civil and abroad.Prophase research on geological characteristics,accumulation pattern and main controlling factors for the reservoir development is done,also carried out on the set of fractured-vuggy carbonate reservoir research,but has not yet formed a complete a set of corresponding technology.We need have a comprehensive prediction technology research to guide the next exploration and development for the key exploration target sequence in sichuan basin?Karst resrviors in Dengying Fm of sichuan basin basically has the following features:1.dominated by dolomites;2.pores,caverns and fractures is the major resrvior space;3.domianed by fractured-porous or fractured-vuggy two type reservoirs;4.had a low porosity and permeability but strong heterogeneity.Before Cambrian deposits,tongwan movement make Sinian Fm suffered varying degrees of erosion,and came out uneven carbonate rocks of the ancient karst landform,"Chasmic trough" on both sides for the karst development area.Based on the controlling factors for the development of reservoir and developmental characteristics of comparative analysis in the study area,Sinian Dengying Fm are mainly controlled by karst palaeogeomorphology and fracture system,so analysis on fractured-vuggy type d etection and karst palaeogeomorphology with high signal-to-noise ratio and high resolution seismic data is the key of the reservoir prediction technique.Firstly,the essay improve the signal-to-noise ratio and resolution of deep sequence seismic data,have a study on deep processing technology,High fidelity,high resolution well control processing technology,rolling surface superdeep low-rising structure prestack depth migration technology,which has greatincreased in signal-to-noise ratio and resolution of Sinian Dengying Fm,ensure the fidelity of wave group characteristics,has a high quality of prestack time migration section,a clear image of “chasmic trough”of purpose layer,a high match degree of internal reservoir characteristics and well synthetic seismogram.Secondly,use "stamping technology","layer flattening technique,residual thickness technology,selected Leshan-Longnvsi paleo-uplift of basin framework seismic section,has a research on tectonic evolution of vertical and plane structure characteristics,elaborate the period of the ancient landform features in Sinian Fm of karst reservoir,determine favorable area.Thirdly,develop the fractured-vuggy technology,post-stack coherent cube technology,curvature attribute technology to predict fracture system and plane distribution,prestack azimuth detection technology,widely azimuth seismic data of the coherent and texture attributes of prestack fractured-vuggy prediction technologFinally,in view of characteristics of sinian Dengying Fm karst reservoir,carry out the comprehensive study on pre-stack and post-stack inversion,combine sparse pulse inversion with pre-stack elastic parameter inversion can elaborate predict characterization of reservoir and flow distributionThe study first pushed the coherence and texture attributes technology to prestack area,which make full use of the wide azimuth anisotropy of seismic data,avoid lithologic seismic waveform change caused by different fractured-vuggy trap.It can predict small cracks,improve the predict accuracy,reduce the multiple solutions,and deep sequence carbonate low-rising structur imaging processing technology and Sinian Fm karst reservoir description technology series are formed;we use a new method innovatively in fluid identification research,which describe the fluid quantitative characteritics of the phenomenon of “low frequency resonance,high frequency attenuation”.Through the adaptability study area of new technology,new method in karst fractured-vuggy reservoir prediction,gradually achieve deep sequence in the quantification of carbonate reservoir description.it has a good result in this study,and provide a theoretical and technical support in further exploration and development of Sinian dengying Formation in Sichuan basin.