Research On Seismic Prediction And Evaluation For The Carbonate Rock In Sichuan Basin

Widely developing in Sichuan Basin, the carbonate reservoir is an important majorreservoir. Aimed at the complicated carbonate reservoir which is greatly anisotropic andcontrolled by many factors, this thesis introduces and applies the nonlinear theory andmethods to the prediction and evaluation of the carbonate reservoir. The prediction andevaluation of the reservoir will thus be quantified to establish the new methods andtechniques of rock reservoir prediction.(1) With the carbonate reservoir geological and geophysical response modeestablished on the analysis of the geological and geophysical response characteristics ofthe carbonate reservoir in Carboniferous, Jialing River Formation and Yangxin Series,and the nonlinear characteristics of the reservoir as its scientific foundation and solidbasis, this thesis creates a new effective series of methods and techniques to predict thecarbonate reservoir. This series is made up of the reservoir internal structure analysistechnology, the seismic high-resolution nonlinear methods and the comprehensiveseismic nonlinear reservoir prediction and evaluation methods. It is a new method andtechnique to predict reservoirs, which will improve the effect and accuracy in reservoirprediction.(2) The reservoir internal structure analysis technology consists of catastrophetheory method, chaos method and correlation dimension method, so it is callednonlinear three-parameter method. As an innovation, this analysis technology can revealuncontinuity and irregularity inside the reservoir and the divergence effect and evolutioncharacteristics of the reservoir during sedimentation and the sequent reformation, aswell as the growth of the reservoir fracture. This technology gives the reservoir researchmore details and provides a closer and more detailed look into the internal structure of the reservoir.(3) The reservoir seismic high-resolution nonlinear inversion method is a newseismic inversion method, which is integrated with genetic algorithm, BP algorithm andchaos-optimization algorithm. The updated embedded hybrid algorithm and theinnovative nonlinear mapping key technology are used in this method, which aresuperior to the conventional hybrid algorithm. A large number of seismic dataprocessing results indicate that the vertical and horizontal change characteristics of thereservoir are clearly and exhaustively reflected on the seismic profile. This kind ofhigh-resolution inversion profile can be used to differentiate the prediction of streak andreservoir. The minimal collectable reservoir thickness is approx. 4.0 m, the error is 2.3%.It has achieved a satisfactory effect in the prediction of the carbonate reservoir inSichuan Basin and has become a core technology in reservoir prediction.(4) The carbonate reservoir seismic nonlinear comprehensive prediction andevaluation method is a new method of predicting and evaluating reservoir, which isintegrated with neural-network technology and fuzzy technology. With the help of fuzzyassociative method, it makes the seismic property parameter space after optimization acton the reservoir seismic nonlinear comprehensive prediction and evaluation system toobtain the comprehensive reservoir evaluation parameters with or without wells. Theseparameters can be used as the quantification evaluation indicators to assess the reservoireffectiveness. The application of the method to the carbonate reservoir in Sichuan Basinshows that the prediction method and algorithm are quite applicable to the complicatedand volatile carbonate reservoir and have achieved great geological effect. It provides astrong technical support to the exploration and development of the carbonate reservoirin Sichuan Basin and brings a new path to the prediction and evaluation of rockreservoir.(5) Based on the two-phase medium reflectivity coefficient and transmissioncoefficient equations, this thesis analyzes the reflectivity and transmissioncharacteristics of the simple theoretic model and provides the calculation method of thetwo-phase medium reservoir parameters. It is a pre-research carried out to develop thereservoir prediction and evaluation to the two-phase medium reservoir prediction andevaluation.(6) To apply the methods and technology in this article to the reservoir predictionand evaluation in Dongxi district, Jialing River Formation, which has achieved a satisfactory effect: expose the growth of the reservoir fracture of Jialing RiverFormation, predict the favor districts, and achieve better geologic effect andeconomic benefit.The development of the reservoir prediction method and technology is bound tomake the prediction nonlinear, make the reservoir internal structure analysis moredetailed and make the reservoir prediction and evaluation quantified. The reservoirprediction and evaluation research will definitely be oriented towards two-phase ormulti-phase medium prediction and evaluation.