Transient Behavior of Vertical Commingled Well in Vertical Non-Uniform Boundary Radii Reservoir

Abstract

Transient behavior analysis, including rate transient analysis (RTA) and pressure transient analysis (PTA), is a powerful tool to investigate the production performance of the vertical commingled well from long-term production data and capture the formation parameters of the multilayer reservoir from transient well testing data. Current transient behavior analysis models hardly consider the effect of vertical non-uniform boundary radii (VNBR) on transient performances (rate decline and pressure response). The VNBR may cause an obvious novel radial flow regime and rate decline type, which can easily be mistaken as a radial composite reservoir. In this paper, we present a VNBR transient behavior analysis model, the extended vertical uniform boundary radii (VUBR), to investigate the rate decline behavior and pressure response characteristics through diagnostic type curves. Results indicate that the dimensionless production integral derivative curve or pressure derivative curve can magnify the differences so that we can diagnose the outer-convex shape and size of the VNBR. Therefore, it is significant to incorporate the effects of VNBR into the transient behavior analysis models of the vertical commingled well, and the model proposed in this paper enables us to better evaluate well performance, capture formation characteristics and diagnose flow regimes based on rate/pressure transient data.

Investigation on the pressure response behavior of two-layer vertical mixed boundary reservoir: field cases in Western Sichuan XC gas field, China

“…Their case studies show that the pressure response of a reservoir with a vertical non-uniform boundary distance can easily be mistaken for the pressure response of a radial composite reservoir. Sun et al [10] have proved that the vertical inhomogeneous closed boundary may produce a fake pressure response behavior of a radial composite reservoir with poor permeability outer zone, and interpreted this phenomenon by a type gas well in the western Sichuan Basin. Shi et al [11] use a two-layer reservoir with different boundary types in the vertical direction show that the pressure response behavior in the radial composite reservoir model probably induced by a two-layer reservoir with one closed bounded layer and another infinite layer, and the pressure response behavior in dual-pore reservoir model may be caused by a two-layer reservoir with one closed layer and another constant-pressure layer.…”