Application of multicomponent seismic in tight reservoir prediction of the first member of Jurassic Shaximiao Formation, Sichuan Basin, China

As the most powerful tool for tight gas prediction and exploration in the second member of the Shaximiao Formation (Sha 2 Member) in the Sichuan Basin, the technique of bright spot fails to deliver satisfactory results in the Sha 1 Member. To address the challenge posed by non-bright spot reservoirs, a multicomponent seismic survey was performed. Seismic responses of tight gas reservoirs in the Sha 1 and Sha 2 members were identified through the analysis of log responses and forward modeling. PP-PS registration was accomplished in the time domain, followed by joint PP-PS prediction of channel sands and gas accumulation in the Sha 1 Member. The results show that: (1) Reservoir porosity in the Sha 1 Member is smaller than in the Sha 2 Member, while bright spots generally correspond to high-porosity sands. Consequently, bright spot reflections are relatively scarce in the Sha 1 Member. (2) Sands in the Sha 1 Member that exhibit weak PP reflections and medium to strong PS reflections can be clearly delineated using PS data, which has led to the discovery of extensive reservoirs in the study area. This research has facilitated multicomponent seismic acquisition and application on a larger scale in the northwestern Sichuan Basin. Newly deployed wells have achieved a ratio of 90% for reservoir penetration, offering an effective support for reserve estimating in the Sha 1 Member.