A Breakthrough in Early Detection and Monitoring of Induced Fracture with Automated Interpretation of Step-Rate Tests

Interpretation of Step-Rate Tests (SRT) is a common approach to detect induced fracturing and monitor the fracture opening and closure time-lapse. Recent developments in the areas of induced fracture detection and automated well monitoring workflows based on Pressure Transient Analysis (PTA) paved the way for a breakthrough in the fracture detection and monitoring. This paper presents how integration of a new detection method within an automated workflow enables early detection and further monitoring of induced fracture.

The new method employs the specific behavior of pressure derivative associated with fracture creation or opening in combination with a Derivative Uncertainty Envelope (DUE) introduced to distinguish the specific behavior from measurement noise. The method is further integrated into the automated well monitoring workflow, developed for on-the-fly interpretation of pressure transient responses, where unique PTA-metrics can assist the method application for highlighting the well performance changes.

Application and verification of the detection method integrated into the automated workflow were carried out through an analysis of time-lapse SRTs of a vertical fractured water injector in the Ivar Aasen field, offshore Norway. The case study has confirmed the method and workflow capabilities in early detection and monitoring of induced fracture, overperforming the standard time-lapse SRT analysis using pressure-rate (p-Q) plot, while giving results consistent with the last one mentioned.

The advantages of the new automated SRT interpretation include (1) automated data preprocessing and transient identification; (2) noise-resistant DUE-driven early detection of fracture creation or opening and (3) simple follow-up of induced fracture development and changes using the PTA-metrics transforming the derivative behavior into a representative well performance indicator. These advantages initiate a breakthrough in SRT interpretation, ensuring early fracture detection, simplifying fracture monitoring and providing basis for on-the-fly analysis and injection control.