Gas Reservoir Prediction In The Fourth Member Of The Dengying Formaion In G Exploration Area,Sichuan Basin

The gas reservoir in in the fourth Member of the Dengying Formaion in Gaoshiti Moxi block has large reserves and great development potential.It is a real resource field for Southwest Oil and gas field company to achieve the goal of 30 billion cubic meters of atmospheric area.At present,the platform margin zone has completed the program preparation and production capacity construction,while the reservoir in the platform becomes thinner and the heterogeneity becomes stronger,so it is difficult to predict the pre formation.In this paper,taking G exploration area in the platform as an example,reservoir prediction research is carried out.Firstly,the fourth member of Dengying Formaion is divided into three sub layers by fully combining geological and logging data,well seismic and detailed stratification.On the basis of calibration results,4 * 4 fine grid densification and fine interpretation are carried out to determine the top and bottom formation attitude of each sub layer.Fault forward response simulation is used to guide fault identification,establish velocity field,and determine the fault strike and formation thickness change of the block.Reservoir characteristics are used to classify the fault It is clear that the reservoir in this block is mainly pore type,mainly developed in 2 and 3 sub layers,and sporadically developed in 1 sub layer,and the reservoir is affected by faults,stratum thickness and paleogeomorphic characteristics.The forward modeling analysis is carried out to analyze the relationship between seismic reflection characteristics and reservoir changes,and the amplitude attribute is extracted for "bright spot",so as to predict the favorable area of reservoir development;the pre stack and post stack petrophysical modeling is carried out According to the relationship between wave impedance and porosity,seismic inversion is carried out to predict reservoir thickness,extract amplitude and structural attributes,predict cave and fracture distribution,and predict reservoir sweet spot area with porosity greater than 3%,thickness greater than 10 m and fracture cavity development as the standard.Hydrocarbon detection is carried out by using spectrum analysis technology,and waveform clustering analysis is carried out by using neural network algorithm to analyze and predict gas reservoir distribution.Compared with the interpretation of reservoir thickness and fracture cavity development of well completion logging,the coincidence rate of reservoir prediction is 86%,fracture prediction 80% and Karst Cavity Prediction 73%,with high prediction accuracy.Based on the above research,the reservoir development mode of "lithologic pinch out and karst fault formed high quality reservoir" in the fourth Member of Dengying Formaion of G exploration area is proposed.Combined with hydrocarbon detection,the natural gas enrichment area is identified,which supports the rolling evaluation deployment and scheme compilation of Sinian gas reservoirs in the platform.