Integrated analysis of pressure response using pressure-rate convolution and deconvolution techniques for varied flow rate production in fractured formations

Abstract

This paper introduces an integrated analysis for pressure transient behavior of conventional and unconventional multi-porous media reservoirs considering varied flow rate conditions. It focuses on the applications of pressure-rate convolution and deconvolution techniques for analyzing pressure records of homogenous single porous media, double porous media, and triple porous media reservoirs. The tasks covered in this paper are: Deconvloving pressure response, characterizing and developing analytical models for new flow regime that represents the impact of varied flow rate at early production time, estimating productivity index, and calculating stimulated reservoir volume (Vsrv). The reservoirs of interests in this study are depleted by horizontal wells intersecting multiple hydraulic fractures and composed of stimulated and unstimulated reservoir volume with different configurations and geometries.Multi-linear flow regimes approach is used to describe pressure behavior in the reservoirs while declining flow rate scheme is described by van Everdingen model. These two models are assembled to deconvolve pressure responses from varied to single flow rate condition. The deconvolved pressure and pressure derivative are used in characterizing the new flow regime that is observed for the case of varied flow rate during early production time and generating analytical models in dimensionless form and field units for oil and gas reservoirs. They are also used to calculate stimulated reservoir volume using very late production time, pseudo-steady state flow is reached, without the need for running well test to this time. Productivity index for constant and varied flow rate are calculated and compared using pressure responses of the two cases. The methodology used in this paper has experienced reservoirs with hydraulic fractures of different characteristics, stimulated reservoir volume (Vsrv) between hydraulic fractures, and unstimulated reservoir volume (Vusrv) in the outer drainage are beyond fracture tips.The outcomes of this study can be summarized as: 1) Introducing an integrated analysis of pressure behavior using pressure-rate convolution and deconvolution techniques for hydraulically fractured conventional and unconventional reservoirs. 2) Deconvloving pressure response from varied to single flow rate condition by applying multi-linear flow regimes approach collaboratively with decline flow rate model proposed by van Everdingen. 3) Characterizing the impact of variable production rate on pressure response for different reservoir types, configurations, and geometries as well as different hydraulic fracture characteristics. The most interesting points are: 1) The main differences in wellbore pressure behavior between variable and constant flow rate can be seen at early production time. 2) The new flow regime that could be developed for varied flow rate at very early production time is characterized by slope of (1.30−1.35) on pressure derivative curve. 3) Productivity index calculated by deconvolved pressure for variable flow rate is slightly less than the index for constant flow rate at early production time, however, the index has the same value for the two conditions at late production time.