Technology Research On Reservoir Prediction For Shawan Formation In Pai 601 Area Of Chepaizi Uplift

Chepaizi uplift lies in the northwest of Junggar basin, which belongs to the secondary tectonic unit of West Junggar upthrust, where is close to the Zhayer mountain in the west and takes Hongche fault Belts as east boundary, while the south boundary is Sikeshu sag and Yilinheiergen mountain and with Kexia fault-folding zone in the north. Chepaizi uplift is a single slope with southeast inclination, and has gone through several subsidence repeatedly during Haixi periods with quite complex tectonic development. There are lots of oil-gas reservoir in Chepaizi area for the reason of special structures and sediments. The Shawan Formation of Neocene is the target formation in this research, which has erosion-unconformity contract with the upper Taxihe Formation and overlap-uncomformity contract with the underlie Cretaceous Formation. The banded sandbody of Shawan Formation overlap with the unconformity surface in northwest direction, and so as to form the formation-overlap reservoir by the shading of upper mud zones.Reservoir prediction is the key technology in the exploration of oil-gas reservoir, which is based on the seismic data and combined with the logging data, utilizing the precise tectonic interpretation, seismic attribute analysis, sub-frequency and seismic inversion to study the distribution of reservoir parameters, lithology and other properties and so as to predict the favorable areas. Reservoir prediction has quite important influence on the exploration and well-drilling plan of the oilfield. For the reason of low density of wellnet, low quality of 3D seismic data, bearing erosion with target formation, confusion of sedimentary models and horizontal anisotropy of sandbody, the prediction for the favorable area is quite difficult and it is necessary to carry out the reservoir prediction research. Based on the 3D seismic data and well logging data, taking the theory of Seismic Sedimentary, Geophysics, Reservoir Sedimentary, Sequence Stratigraphy as the guide, and combined the results of predecessors, firstly carry out the seismic sequence stratigraphy research, study the characteristic of sequence stratigraphy in Shawan Formation of Pai601 area by using the techniques of precise synthetic seismogram, comprehensive demarcate with multi-well, time-frequency analysis. Secondly, guided by the theory of sedimentary facies-controlled, divide the favorable facies zone with the techniques of seismic attributes analysis, formation slice and attributes optimization. Finally, study the lithology and characteristic parameters of the reservoir and inner character of sediments to predict the target zones by using the seismic inversion with well constraint and multi-attribute non-linear seismic inversion, and gets quite good application results.(1) Guided by the theory of seismic stratigraphy and sequence stratigraphy, identify the unconformity surface of target formation and the seismic refection characters, while the unconformity surface of bottom Shawan Formation is the significant channel for transporting oil and gas and has key influence on the formation of oil-gas reservoir. By using the techniques of precise synthetic seismogram, comprehensive demarcate with multi-well, time-frequency analysis to study the sequence stratigraphy characteristic of inner sand formation and utilizing the 3D visualization, time slice and arbitrary lines to the precise interpretation.(2) Based on the facies-controlled theory, combined the analysis results of petrophysics characteristic and single well, divide the favorable reservoir zones by using the techniques of seismic attributes analysis, formation slice and attributes optimization and classification. The RMS amplitude has quite good relationship with the thickness of sandbody, especially for the oil-bearing sand in first member of Shawan Formation with the characters of"lightspot". However some parts of wells have difficulty in distinguishing the sand bearing with water or oil. By the precise study of multi-attribute extraction and classification, to describe the favorable reservoir zones in the target area.(3) Study the lithology and characteristic parameters of the reservoir and inner character of sediments to predict the target zones by using the seismic inversion with well constraint and multi-attribute non-linear seismic inversion. Build the reasonable geology modeling by well logging standardization and precise demarcation to carry out seismic inversion, and takes the impedance data into multi-attribute PNN inversion with good correlation, which the coefficient is 0.82.This study results has been applied to various lithological reservoir exploration in Chepaizi area, and have given great guidance to the exploration. Contrasting with the known drilling wells, and the success rate of prediction is greater than 70%. This study results have got obvious geological effects and economic benefits so as to verify the instructive significance of the research.