Production Analysis of One Shale Gas Reservoir in China

摘要

China is the third country gaining shale gas breakthrough in the world after the United States and Canada. Fuling shale gas play is the most successful shale gas reservoir by far in China with average absolute open flow (AOF) capacity of 400 thousand cubic meters per well and the amount reaches 8 million cubic meters in one year for some wells. However, production rate and pressure transient analysis show quite different flow regimes which may mean that the wells are producing quite differently and stimulating treatment have distinct performance. In this paper, 20 wells in the shale gas reservoir in China are analyzed with production rate and pressure transient data using rate normalized pressure (RNP) and rate normalized pressure derivative (RNP’) method. The 20 wells log-log interpretation plots are drawn to diagnose the flow regimes and flow regime sequence. In the log-log plots, nearly half of the wells see unit slop, which indicate boundary dominated flow within 1 to 2 years, so the stimulated reservoir volume (SRV) is very small. From production rate data, most producing wells see interference when their neighborhood wells are hydraulic fracturing. Interference imposes great effect on log-log interpretation plots, so interpretation comparison are made with and without using rate and pressure transient data after interference. Because of interference, liquid loading may be a problem for some wells. External source of energy supplying for the shale gas layer is researched by rate and pressure transient interpretation modeling because some wells see external pressure supply. Results show that Fuling shale gas reservoir has unique production performance with production rate keeping nearly constant within 2 years for some wells. Fuling Phase I shale gas wells exhibit 4 different flow regimes with relevant interpretation models categorized by homogenous formation with boundary, dual porosity formation, pressure support, severe liquid producing. Interference with adjacent wells during hydraulic fracturing may occur and cause great effect on rate and pressure transient data interpretation. To the author’s knowledge, this is the first time that comprehensively describes shale gas production performance detail in China. 4 different flow regimes with different formation interpretation models within one reservoir block are rarely