Production analysis and forecast in unconventional reservoirs are challenging tasks due to high degree of uncertainty and non-uniqueness associated with well/reservoir properties. At this point the importance of diagnosis of production data to check the data consistency and to identify flow regimes has become significant. In addition, we believe that producing wells in various unconventional reservoirs exhibit unique production performance behavior due to geology, phase behavior, and completion practices. Therefore, the identification of the related performance behavior is crucial for development and forecast purposes.
The primary objective of this work is to apply diagnostic methods to investigate and understand production performance characteristics of the wells producing in unconventional reservoir systems. For our purposes, we present examples from various shale gas plays.
We propose the use of various forms of rate-time and rate-time-pressure plots for production data diagnostics. In particular, this work presents the utilization of the dimensionless q,cp-derivative formulation (i.e., logarithmic derivative of the rate function with respect to logarithm of time) to identify production behavior characteristics. We also propose the use of several diagnostic plots to identify performance characteristics and data consistency. In addition the use of average rate functions are presented for better resolution.