Study On Integrated Logging Evaluation Of The Fractured-vuggy Reservoir

Solution pores,caves and fractures provide the main storage and seepage channel for fractured-vuggy reservoirs.The randomness and complexity of their distribution seriously affect the quantitative evaluation of fractured-vuggy reservoirs.At present,there is still a lack of effective logging interpretation and evaluation methods for fractured-vuggy reservoirs.In order to improve the standard of the logging interpretation and evaluation of fractured-vuggy reservoirs,it is necessary to carry out the research in three aspects including the conventional logging,electric imaging logging and full-waveform multichannel sonic logging,and to realize the quantitative characterization and evaluation technology based on the comprehensive logging data.Aiming at these problems exist in the recognition of fractured-vuggy reservoirs by the conventional logging data,it is necessary study the logging responses of different reservoir types based on the analysis of the corresponding relationship between different pore types and pore structures in the researched area.An improved method based on the principal component analysis is applied to construct the comprehensive fractured-vuggy index,and to quantitatively identify three reservoir types.The classification standard and identification map of reservoir types in the study area have been established,and the comprehensive and fast evaluation of fractured-vuggy development have been realized.The effectiveness of the comprehensive fractured-vuggy evaluation index is verified by the application results.More reasonable results are obtained for the evaluation of fractured-vuggy development and its relationship with reservoir productivity than traditional logging methods.For the fine evaluation on pore structure and quantitative parameters characterization in fractured-vuggy reservoirs,the morphology method is applied to automatically separate fractures and vugs based on the electric imaging logging data with the high coverage rate and resolution.Combined the response characteristics of fractures and vugs in the electrical imaging images,the structure elements with appropriate shape and size are selected,morphological filtering operators in different types are constructed,and the abnormal edge detection of fractured-vuggy body is achieved.For the one-dimensional morphological algorithm,to enhance the fractured-vuggy information in the electrical imaging images,the noise of the original data from button electrode plates are suppressed and other geological characteristics except fractures and vugs are removed.For the two-dimensional morphological algorithm,an automatic identification and extraction method of fractures and vugs based on the path morphological algorithm are established.Matix pore,fracture and vugs can be separated,and fractured-vuggy pore structure spectrum is calculated by the novel method.Test examples of numerical simulation data and several measured wells data have been provided for the verification of the effectiveness and adaptability of the multi-scale path morphology method in application of electric imaging logging data processing and giving algorithm support for the fine evaluation of fractured-vuggy reservoir.For predicting reservoir fluid accurately,a frequency-division cross-correlation method based on slowness-time correlation(STC)algorithm is proposed to obtain the dispersion of P-wave velocity using the full-waveform multichannel sonic logging data.The acoustic data are decomposed into a series of frequency components,and similarity matrix of each frequency component waveform in the time-velocity domain is computed by STC algorithm.The cross-correlation of similarity matrix with adjacent frequency component is calculated,then the velocity gradient and velocity dispersion curve are obtained.The velocity dispersion characteristics of XMAC and DSI instrument are analyzed,the influence of oil on acoutic dispersion and attenuation is explored,the attenuation mechanism and rock physical properties are summarized,and reservoir fluid are predicted in fractured-vuggy reservoir.Comparing the results of the new method with conventional logging and electrical imaging logging,it indicates that velocity dispersion corresponds well with oil-bearing reservoirs.The accuracy and reliability of this method are verified,which also provides a favorable indication for reservoir fluid identification.The study of the evaluation method of the comprehensive logging for fractured-vuggy reservoirs is of great significance for solving the reservoirs evaluation,guiding the exploration and deployment,formulating the development plan,selecting the mining technology and so on.At the same time,it also provides the technical support for the target of stable production of 8 million tons in huabei oilfield.