SRV Analysis of Shale Gas Wells in China

Abstract

Abstract China owns the world's largest shale gas reserve and is the third country gaining shale gas breakthrough in the world besides the North America. Fuling in Sichuan basin is the first industrially exploited shale gas play in China. Fuling shale gas wells gain good production performance, and the gas rate of some wells are as high as 0.6 million m3 during production test period. However, we still haven't get good understanding of SRV, one vital indicator to evaluate the performance of hydraulic fracturing in Fuling shale gas play. Production rate and pressure transient analysis by rate normalized pressure (RNP) and rate normalized pressure derivative (RNP’) method is adopted. The SRV of the pilot wells in Fuling shale gas play is estimated from the boundary dominated flow in the RNP and RNP’ log-log interpretation plot. In order to quantify the influence of parameters on SRV, statistical analyses are conducted on fourteen parameters categorized by three kinds including formation, stimulation, and well parameters. Results show that the parameters are angle between horizontal lateral and minimum stress direction, TOC, absolute open flow (AOF) potential, cumulative gas in first three months, injected fluid volume, porosity, injected fluid volume per stage, fractured clusters, fractured stages, injected proppant volume, flowback recovery in first three months, injected proppant volume per stage, proppant concentration, and horizontal lateral length sorted by the influence on SRV in descending order. The first five parameters have relative strong correlation with SRV. High TOC, porosity and cumulative gas production in early days are good indication of high SRV. Shale gas wells with horizontal lateral paralleled to the minimum stress direction can achieve highest SRV. The other nine parameters, especially proppant concentration and horizontal length show very weak influence on SRV. The negative correlation of proppant concentration on SRV may have been caused by ineffective fractures (networks), and a positive correlation can be achieved by detailed research of geology and engineering "sweet points" and improved hydraulic fracturing techniques to control fracture propagation. The relationship between SRV and flowback recovery may have been disturbed by offset well's interference during hydraulic fracturing and production.