Reservoir Types and Gas Well Productivity Models of Member 2 of Dengying Formation in Pengtan1 Block, Sichuan Basin

The Member 2 of Dengying Formation gas reservoir in Pengtan 1 block of Sichuan Basin is mainly controlled by deposition of mound-shoal complex, penecontemporaneous karstification and supergene karst. Due to the cause of multi-factor superposition, there are some limitations in reservoir characterization of Member 2 0f Dengying Formation according to the exisiting reservoir classification and evaluation criterion. Based on core observations, conventional and imaging log data analyses, CT core scanning and thin section identification, the reservoirs of Member 2 of Dengying Formation in Pengtan1 block can be divided into pore type, fracture-pore type, karst cave type, fracture-karst cave type with matching reservoirs spaces. Among them, the fracture-karst cave and karst cave reservoirs have the characteristics of good physical properties, easy exploitation and good pilot production, and are the high-quality reservoir type in Member 2 of Dengying Formation. In addition, one the basis of fine reservoir classification in single wells, application of conventional seismic reservoir prediction, as well as analyses of the dynamic data such as well test curves, production curves and open flow capacities of typical wells, the division scheme of gas well productivity can be establish and the productivity models can be classified into three categories(Ⅰ, Ⅱ and Ⅲ) for Member 2 of Dengying Formation in Pengtan 1 block. The high-quality reservoir has a high proportion in the productivity model Ⅰ and model Ⅱ, showing the top boundary of the upper sub-segment of Member 2 of the Dengying Formation exhibiting amplitude energy weakening and complex wave characteristics, or the middle part of the upper sub-segment of Member 2of Dengying Formation exhibiting wide wave valleys and strong wave peaks, and good effects during pilot production.