四川盆地中南部寒武系筇竹寺组超深层页岩气地震关键技术及发展方向OA

The Cambrian Qiongzhusi Formation in the Sichuan Basin has immense potential for shale gas exploration,but due to its great depth and considerable thickness,intralayer seismic reflection signals are weak with low resolution.As a result,internal geological cycles are ambiguous,the continuity of layer interfaces is poor,fault points and surfaces are not clearly defined,and micro-amplitude structures are not determined,which hampers fine exploration and development.Based on the existing seismic data,this paper carries out targeted research on seismic data processing and sweet spot prediction.In addition,the effectiveness of the technology is verified through practical engineering.The following results are obtained.First,the high-fidelity denoising technology based on weak signal protection,the multiple identification and suppression technology,the Q-tomography and Q-migration resolution enhancement technology,and the reverse-time migration imaging technology are developed,and their application increases the dominant frequency of the target layer by 5 Hz and widens the frequency bandwidth by 10 Hz,improving the capacity of layer identification.Second,the shale sweet spot prediction technology driven by petrophysical model,the brittle mineral content prediction technology for shale,the three-dimensional geostress prediction technology,and the neural network based fracture probability detection technology are established,and their application delivers a geological sweet spot prediction accuracy exceeding 90%and an engineering sweet spot prediction accuracy exceeding 80%.Third,structural fractures are characterized more precisely,enabling the gas content,enrichment,and fracability evaluation of shale intervals,and confirming the distribution of geological-engineering sweet spots.Fourth,the seismic research achievements support the efficient exploration and large-scale reserves submission of the Qiongzhusi Formation ultra-deep shale gas in the Weiyuan-Ziyang area,the formulation of pilot three-dimensional development plans,and the construction of 1×109 m3/a production capacity in the lower submember of the second member of the Qiongzhusi Formation,ensuring a 100%drilling rate of high-quality reservoirs and an average daily tested production exceeding 1×106 m3.Fifth,To meet the demands for ultra deep and multi-layered systems,multi type exploration and evaluation,and three-dimensional development in the Qiongzhusi Formation,technology iteration and upgrading direction centered on high-density seismic technology has been proposed.In conclusion,the research findings can effectively address the challenges to the exploration and development of the Qiongzhusi Formation shale gas,ensure the large-scale and efficient development of ultra-deep thick shale gas reservoirs,and are of reference significance for the exploration and development of similar shale gas in other areas.