Unified transient analysis (UTA) of production and shut-in data from hydraulic fractured horizontal wells

Abstract

Market-induced production shut-downs and restarts offer us an opportunity to gather step-rate and shut-in data for pressure transient analysis (PTA) and rate transient analysis (RTA). This study presents a unified transient analysis (UTA) to combine PTA and RTA in a single framework. In this new approach continuous production data, step-rate data, shut-in data and re-start data can be visualized and analyzed in a single superposition plot, which can be used to estimate both A f k and infer formation pore pressure in a holistic manner by utilizing all available data. Most importantly, it shows that traditional log-log and square root of time plots can lead to false interpretation of the termination of linear-flow or power-law behavior. Field cases are presented to demonstrate the superiority of the newly introduced superposition plot, along with discussion on the calibration of long-term bottom-hole pressure with short-term measurements. • A unified transient analysis (UTA) is proposed to unify rate and pressure transient analysis of hydraulic fractured horizontal wells. • Inexpensive short-term bottom-hole pressure measurement is beneficial to calibrate long-term bottom-hole pressure. • Traditional log-log plot and square root of time plot may falsely interpret formation linear-flow as power-law behavior. • Hydraulic fracture surface area can be overestimated if only surface measurements are used.