Integrated Analysis Combining Microseismic Mapping and Fiber-Optic Distributed Temperature Sensing (DTS)

Abstract

Mapping the microseismic activity during a hydraulic treatment is widely used to determine the geometry of the stimulated fracture network. Microseismic maps provide reliable information on the development of fracture symmetry, half-length, azimuth, width and height, and their dependence on the treatment parameters and reservoir characteristics. Beyond that, these fracture geometries are used to better understand fracture modeling and even production characteristics. Fiber-optic-based distributed temperature sensing (DTS) arrays provide almost immediate updates of the near-wellbore temperature distribution in approximately one-meter intervals. In injection treatments, the near-wellbore temperature distribution can be used to determine isolation effectiveness, the relative amount of fluid each perforation cluster takes, fracture initiation points, and effective fluid diversion. In production analysis, DTS measurements can quantify production rates from each perforation interval, crossflow rates while shut-in, and fluid types recovered from each perforation interval. The detailed near-wellbore results available through DTS coupled with the far-field geometry acquired through microseismic mapping provide an accurate picture of the completion effectiveness. Microseismic mapping results often show adequate resolution over a large area but lack the fine resolution that would allow it to identify near-wellbore effects in the meter range. When modeling and interpreting the treatment geometry obtained by the microseismic-event distribution, it is important to include the correct near-wellbore effects, which are readily accessible through DTS measurements. Combining the two diagnostic tools is valuable for real-time decision making, post-treatment analysis, and production analysis to assess the completion effectiveness. Incorrect assumptions about perforation breakdown, fracture-initiation points, interval isolation, or limited-entry effectiveness can lead to misinterpretations of the microseismic results. Using both diagnostic tools provides firm answers to the overall completion effectiveness. This paper focuses on three distinct aspects of combining the analysis of microseismic mapping and DTS. The first is the real-time aspect, wherein real-time decisions and adjustments are made during the fracture treatment with the objective of manipulating the results towards the desired outcome. The second is using both tools to perform more accurate postfracture analysis, including calibrated fracture modeling, entry effectiveness, correct interval spacing, and stimulated reservoir volume (SRV) analysis. The third area covered is combining these diagnostic tools with a production analysis, which is acquired through analysis of the temperature data.

A Validation Assessment of Microseismic Monitoring

“…This particular case was in a reservoir where the hydraulic fractures were very planar and such details were clearly observable. Holley et al (2010) show the challenge of evaluating fracture behavior from a single port using only microseismicity in the Barnett, where the fracturing is relatively complex. In one stage (Stage 1), DTS clearly shows the fracture initiating at only one port, but the microseismicity has significant width.…”

“…Fiber-optic monitoring using both distributed temperature sensing (DTS) and distributed acoustic sensing (DAS) can be used in both the treatment well (Huckabee 2009;Holley et al 2010;Molenaar and Cox 2013;Cakici et al 2013;Ugueto et al 2014) and in offsets wells (Webster et al 2013). In the treatment well, the distributed sensing technologies can provide information on the distribution of fluids among perforation clusters, the location(s) of persistent fractures (indicative of volume), and isolation issues that might cloud interpretation of any microseismic data.…”

Novel Technology for Downhole Reality Check and Realization – A Case Study of Real-time Monitoring of High-Rate Matrix Acid Stimulation Treatments in a Tight Chalk Reservoir using Distributed Temperature Sensing

“…DTS analysis and interpretation is based upon a comparison of temperature changes along the wellbore used to infer areas of fluid flow and reservoir entry [3][4] . The temperature in the immediate vicinity of the borehole is measured using a customized fiber-optic cable.…”

Laboratory evaluation of distributed coaxial cable temperature sensors for application in CO2 sequestration well characterization

“…(iv) Low spatial resolution. Depending on the relative position of the observation well, the resolution of the microseismic results might be a few meters, which is not sufficient to answer detailed questions regarding points of fracture initiation from the wellbore . (v) Impact of environmental factors.…”