Summary

This technical paper introduces a new frontier in fiber-optic surveillance: Optiq™ real-time (RT) interpretation and analysis solution for injection profiling. Readers will learn how SLB applies an advanced Pressure Temperature Rate Analysis (PTRA) model to continuous distributed temperature sensing (DTS) data, unlocking high-resolution, real-time insights without requiring well interventions. Field trials demonstrate how Optiq RT analysis matches or outperforms conventional production logging tools (PLT) and reveals both injectivity and pressure distribution—delivering greater confidence in injection conformance decisions. The paper also explains how transient thermal modeling overcomes traditional DTS interpretation challenges.

What is Optiq RT analysis and how does it enhance injection profiling?

Optiq™ RT analysis is a real-time fiber-optic interpretation and analysis solution for water injection wells. It uses a novel, fully transient Pressure Temperature Rate Analysis (PTRA) method to convert continuous distributed temperature sensing (DTS) data into actionable injection profiles and reservoir pressure insights.

Why is Optiq RT a breakthrough in DTS interpretation?

• Automated and model-based

Delivers real-time interpretation after commissioning—without manual intervention.

• Improves reliability

Resolves common challenges with early-stage warm-back DTS data—especially in wells with crossflow or induced fractures.

• Validated against PLT data

In a field case, Optiq RT profiles matched conventional production logging tool (PLT) measurements, with differences attributed to fracture timing—highlighting the value of continuous versus snapshot data.

• Beyond injectivity

The analysis estimates both injectivity profiles and reservoir pressure distribution, supporting deeper reservoir understanding.

What value does Optiq RT analysis deliver?

• Continuous, high-fidelity insight across the wellbore without well intervention
• Enables real-time DTS interpretation and fast decision-making
• Supports fiber-optic injection profiling for enhanced waterflood performance
• Reduces uncertainty in injection conformance and zonal distribution

Where has Optiq RT analysis been field-tested?

• The technology has been validated through multiple field trials, including:
• A warm-back test in a well with induced fractures
• A PLT comparison showing strong alignment in injectivity profiles

Paper Abstract

Fiber Optic Systems, such as Distributed Temperature Sensing (DTS), have been used for wellbore surveillance for more than two decades. One of the traditional applications of DTS is injectivity profiling, both for hydraulically fractured and non-fractured wells. There is a long history of determining injectivity profiles using temperature profiles, usually by analyzing warm-back data with largely pure heat conduction models or by employing a so-called "hot-slug" approach that requires tracking of a temperature transient that arises at the onset of injection. In many of these attempts there is no analysis performed for the key influencing physical factors that could create significant ambiguity in the interpretation results. Among such factors we will consider in detail is the possible impact of cross-flow during the early warm-back stage, but also the temperature transient signal that is related to the location of the fiber-optic sensing cable behind the casing when the fast transient data are used for interpretation such as the "hot slug" during re-injection.

In this paper it will be shown that despite all such potential complications, the high frequency and quality of the transient data that can be obtained from a continuous DTS measurement allow for a highly reliable and robust evaluation of the injectivity profile. The well-known challenge of the ambiguity of the interpretation, produced by the interpretation methods that are conventionally used, is overcome using the innovative "Pressure Rate Temperature Transient Analysis" method that takes maximum use of the complete DTS transient data set and all other available data at the level of the model-based interpretation. This method is based on conversion of field measurements into injectivity profiles taking into account the uncertainty in different parts of the data set, which includes the specifics of the DTS deployment, the uncertainty in surface flow rates, and possible data gaps in the history of the well.

Several case studies will be discussed where this approach was applied to water injection wells. For the analysis, the re-injection and warm back DTS transient temperature measurements were taken from across the sand face. Furthermore, for comparison, injection profiles were also recorded by conventional PLTs in parallel.

This case study will focus mostly on the advanced interpretation opportunities and the challenges related to crossflow through the wellbore during the warm-back phase, related to reservoir pressure dynamics, and finally related to the impact of the method of DTS deployment. In addition to describing the interpretation methodology, this paper will also show the final comparison of the fiber-optic evaluation with the interpretation obtained from the reference PLTs.