AOF Analysis of One Shale Gas Play

Abstract

China is believed to own the world's largest shale gas reserve and is the third country to exploit shale gas breakthrough in the world. Fuling gas play in Sichuan basin is one typical shale gas reservoir in China gaining good production performance, and the absolute open flow capacity (AOF) of some wells reaches as high as 1.5 million cubic meters per day. However, we still haven't get good understanding of AOF to evaluate the producing potential and performance of hydraulic fracturing in Fuling shale gas play. In order to quantify the influence of parameters on AOF, statistical analyses are conducted on fourteen parameters including formation porosity, total organic carbon (TOC), injected fluid volume, injected proppant volume, injected fluid volume per stage, injected proppant volume per stage, proppant concentration, fractured stages, and fractured clusters, horizontal lateral length, angle between horizontal lateral and minimum stress direction, cumulative production in the first three months, stimulated reservoir volume (SRV) and flowback recovery in the first three months. Results show that six parameters including cumulative gas in first three months, angle between horizontal lateral and minimum stress direction, SRV, TOC, porosity and injected fluid volume show relative strong correlation with AOF with coefficient bigger than 0.50. The influence of the other nine parameters on AOF is very weak, and the coefficient between AOF and water flowback recovery in early days is even as small as 0.11. AOF is negatively correlated to three parameters including proppant volume per stage, proppant concentration, and angle between horizontal lateral and minimum stress direction. The negative influence of proppant concentration on AOF may have been caused by ineffective fractures (networks), and a positive correlation can be expected if proppants are injected into "sweet points" that meet the geology and engineering requirements and improved stimulation techniques with better performance of fracture propagation control. The angle between horizontal lateral and minimum stress direction is suggested to be less than 20° in order to get bigger AOF. AOF is positively correlated to the other eleven parameters. High TOC, porosity, injected fluid volume are good indication of high AOF.