Wellbore Monitoring in Unconventional Reservoirs: Value of Accurate DTS Interpretation and Risks Involved

Abstract

Wellbore monitoring techniques are proving to be significant in reservoir management and intervention design, particularly in unconventional fields where fluid flow behavior is not very well understood. Distributed temperature sensing (DTS) technology allows for an estimation of zonal flow rates in the entire well as a function of time during hydraulic fracturing, as well as during the production phase.In this work, a novel transient thermo-hydraulic model that includes fluid transport and thermal coupling and simulates fluid flow and temperature in both the wellbore and reservoir is presented. Real DTS data from a hydraulic fracturing operation in a low-permeability basin in west Texas has been inverted using this model. Flow allocation based on the thermohydraulic model is presented. It was found that the reservoir heterogeneity, and hence the zonal flow rates, can be accurately obtained based on temperature and pressure data from the well.Most of the steady-state DTS data inversion models are typically applicable to production scenarios, where the transient in temperature has vanished. Injection operations, such as in fracturing where the temperature does not achieve a steady-state during the injection stage, require a transient model that can capture the initial-time effects. Also, some of these models fail to include the Joule-Thomson effect, and this leads to an incorrect flow allocation. The thermo-hydraulic model developed in this work includes both the Joule-Thomson and transient effects. It can be applied to non-reactive fluid injection during stimulation operations, such as matrix acidizing and fracturing. In particular, application of the model for fluid distribution before, during, and post-fracturing provides an estimate of the efficiency of fracturing stages.

Distributed FiberOptic Sensing for Hydraulic-Fracturing Monitoring and Diagnostics

“…Once the injection is stopped, the temperature begins to rise. Therefore, the perforation cluster efficiency can be obtained by comparing the temperature variation curves of the injection phase and the temperature recovery phase [13,14].…”

Fiber-optic Monitoring: Stimulation Results from Unconventional Reservoirs

“…Several studies have been published around injection profiling, production profiling, leak detection analysis, etc. There has also been significant work during the past several years to use DTS data to deliver quantitative fluid distribution during hydraulic fracturing, as opposed to qualitative results (Kalia et al, 2014). Thermo-hydraulic injection profiling models have been developed that can provide more confident solutions around quantitative cluster efficiency for PnP wells, points of fracture initiation for PnS wells, and fluid communication between stages for either tubular or annular leaks.…”

Distributed Fiber Optic Vibration Signal Logging Well Production Fluid Profile Interpretation Method Research

“…Distributed fiber optic vibration signal logging is a technique that uses fiber optics to sense vibration signals returned from different formations or well walls throughout the transmission path for formation characterization and downhole event analysis [13][14][15][16]. This technology not only provides real-time continuous downhole information but also allows static testing with less interference to well production, easy access to the well, and is competent for small-size tubular columns.…”