EAGE Workshop on Fiber Optic Sensing for Energy Applications in Asia Pacific

Geothermal Steam Production Optimization via Application of Distributed Temperature Sensing

In recent years, distributed acoustic sensing (DAS) has gained large popularity in applied geophysics. Development of helically wound cables (HWC) has pushed the technology forwards for land applications. HWCs are designed to mitigate the directional sensitivity of fibre cables and provide a suitable and cost-effective tool for permanent subsurface deployments for reservoir monitoring tasks. However, a number of field experiments have revealed that seasonal variations of near surface conditions significantly affects the quality of data. We study these effects over an extended period of time and demonstrate how data quality of a buried HWC is changing over a year.

Temperature and Strain Separation from a Distributed Rayleigh System

A Case Study on The Monitoring of Dual-String Heavy Oil Producers in Field B, Malaysia, Using Distributed Fibre Optic Acoustic and Temperature Sensing

DAS 3DVSP Data Acquisition for Methane Hydrate Research

Acquisition and Processing of Multi-fiber DAS Microseismic in the Montney Formation

Distributed acoustic sensing (DAS) is an emerging technology which is increasingly used to monitor changes of the formation properties, monitor production noise, micro-seismic activity as well as a sensor in active seismic surveys. At the same time, data recorded with DAS systems are very rich and not yet fully utilized and well understood. This paper presents our attempt to systematically characterize data recorded passively with a DAS system over a prolonged period of time in the Perth metropolitan area, Western Australia.

In recent years, distributed acoustic sensing (DAS) is increasingly gaining popularity in exploration geophysics. Due to the preferential sensitivity of optical fibres to record the approaching energy, which is along a cable length, this technology is especially suitable for borehole seismic applications. Standard telecommunication fibre optic cables can be used for the disposable permanent installations considering their inexpensive costs. Such sensors are a very cost-effective approach for coal seams exploration. Here we present results of a DAS 3D VSP survey on a coal exploration site in Queensland, Australia. One of the challenges in the area is a substantial spread of a near-surface basalt layer that introduces difficulties for normal surface seismic due to its high velocity contrast with the surrounding formations. DAS cables were installed in a well and cemented. The outcome has shown clear imaging of the target coal seam around the well. Application of DAS in downhole configuration has proven to be an effective method for reliable tracing of coal formations and is particularly useful in the presence of basalt cover.

Seismic While Drilling (SWD) has been underwhelmed in recent years due to the inherent issue of low signal to noise ratio (SNR). With the advent of fiber optic Distributed Acoustic Sensing (DAS) and increasing utilization for seismic surveys, we propose to integrate this emerging technology with conventional SWD. By deploying DAS cable in a borehole environment, the recorded drill-bit signals are less prone to contamination of surface noise, especially from drilling rig. Here we present data acquired from CO2CRC Otway site whilst new boreholes were under drilling. The recorded data in general is of good quality and the most evident characteristic is that the recorded waveforms are repetitive over a short time window due to the repeated impulses emitted from the drill-bit. Based on this character, we designed a new technique, called shift and stack, to further improve SNR. After applying the technique, SNR is improved dramatically at a single drill-bit impulse position. The encouraging results demonstrate that SWD and borehole DAS cable can be integrated as a new powerful tool in probing subsurface. Additionally, the obtained high definition waveforms after shifting and stacking can be used together with conventional surface or VSP surveys to produce more accurate velocity models.

Pipeline Geotechnical Monitoring in Unstable Terrains with Fiber Optic Distributed Sensing