Downhole Monitoring of Multicluster, Multistage Horizontal Well Fracturing with Fiber Optic Distributed Acoustic Sensing (DAS) and Distributed Temperature Sensing (DTS)

Abstract

Fiber optic distributed temperature sensing (DTS) and distributed acoustic sensing (DAS) have been used to monitor and diagnose the integrity of wellbores (leak detection, gravel-pack screen damage, formation subsidence), the performance of reservoirs and wells (production profile, injection profile), used for surveillance and communication networks for quite some time. Though still somewhat novel, the application of high-resolution fiber optic DAS and DTS during multistage hydraulic fracturing has increased in recent years. This paper shares DAS and DTS images of fracture initiation, fracture propagation and fracture progression during fracturing treatments of multicluster (each stage), multistage horizontal tight-gas well. The images illustrate the dynamics pertaining to initiation, propagation and arrest of hydraulic fractures during simultaneous stimulation of multiple clusters. First, fracture initiation appears not only during early time, as expected, but late time initiation events may develop in seemingly dormant clusters. Second, propagation of multiple fractures can occur randomly within a cluster array. Third, dominate clusters are often observed during stimulation. Further, during the treatment cycle, the position of dominate cluster(s), within a given stage, may actually change.

Flow Rate Profile Interpretation for a Two-Phase Flow in Multistage Fractured Horizontal Wells by Inversion of DTS Data

“…From DAS and DTS maps, the interpretation of fracture propagation and progression has been performed for an MFHW with multiclusters in each fracturing stage. 11 − 13 With the help of DTS and DAS maps, Molenaar et al described how to optimize the fracturing stimulation briefly. 14 Except for the DTS/DAS measurements during the fracturing period, successful identification of hydraulic fracture from the measured DTS profile during the warm-back period was carried out by Ugueto et al as well.…”

Research Progress of Applying Distributed Fiber Optic Measurement Technology in Hydraulic Fracturing and Production Monitoring

“…The joint DAS not only determines whether fracturing fluid is leaking during fracturing but also shows the extensional state of the fracture. During fracturing, the DAS detects acoustic activity below the bridge plug (warmer colors detect acoustic signals), while the DTS also shows the cooling effect below the bridge plug [35] (cooler colors indicate fluid inflow), indicating a fluid leak between fractured sections. When the flow rate is too fast, resulting in a slow temperature response, the use of a double-head installation in a U-shape can improve the measurement accuracy in horizontal wells.…”

Introductory Chapter: Developments in the Exploitation of Unconventional Hydrocarbon Reservoirs

“…Various designs of hydraulic fracturing operations are currently implemented in practice; an example is multicluster-multistage horizontal well fracturing (e.g. [5,6]).…”