Fracture Reservoir Rich Gas Bearing Area Forecast By Means Of Rock Physical Parameters Inversion

Upper Triassic Xujiahe-T3x formation currently is the hot point of deep stratum natural gas exploration in west Sichuan depression and is also the main reservoir production growth layer. But because T3X2 gas reservoir has "four specialties and two complexes" characteristics such as ultra deep, ultra tight and low porosity, ultra later period structure, high pressure and complex gas-water contact, complex heterogeneity characteristics of the reservior, it is a big challenge to forecast and identify such a complex gas bearing area by means of conventional seismic exploration technology. Especially fracture forecast and gas bearing identification have become the biggest problems of T3x seismic exploration in western Sichuan depression.To meet the demand of practical exploration and production progress in Xinchang gas field, this paper focus on the high production abundance zone prediction of ultra tight fracture reservoir in T3X2 formation,utilized the 3D3C seismic data in large scale, conduct systematic rock physical analysis, formulated the rock physics model and seismic reflection characteristics of different reservoir, extract the sensible elastic parameter or parameter combination of favorable reservoir, point out the criterion of favorable reservoir in elastic parameter chart, and provided the theory reference and quantitative standards for favorable reservoir and rich gas bearing area forecast. Based on those jobs, intersect explanation of impedance, poisson's ratio and others seismic elastic parameters, which mainly come from the PP/PS wave post-stack joint inversion results, forecast the favorable reservoir distribution of T3X2 formation. To overcome the uncertainty of conventional AVO hydrocarbon detection methods in this area, which mainly belong to I and II class AVO, a separate frequency AVO hydrocarbon detection method and liquid density gas water contact identification method has been experimentally tested to detect the hydrocarbon in T3X2 formation. At the same time, multi-attributes clustering fracture forecast and PP/PS wave joint fracture forecast have also been conducted. Lastly, the ultimate rich gas bearing area has been formulated on the basis of those research results and the well drilling plan suggestions has been submitted. Popularization and application of above research results provide substantial technical support to the increase of gas reserve and production of Southwest oil and gas Branch Co. SINOPEC, and achieved great exploration and development progresses. During the paper research process,20 wells have been proofed and implemented to the exploration and production of T3X2 formation. Successful application of the research result raises the success ratio of drilling from 50% to 89%, raise the success ratio of high production from 17% to 67% and provide strong support for the 1211.2 X108 m3 proven reserves submitting in T3x2 formation of XinChang gas field.