Dual-well 3D vertical seismic profile enabled by distributed acoustic sensing in deepwater Gulf of Mexico

Abstract

We have acquired and processed 3D vertical seismic profile (VSP) data recorded simultaneously in two wells using distributed acoustic sensing (DAS) during the acquisition of the 2012 Mars 4D ocean-bottom seismic survey in the deepwater Gulf of Mexico. The objectives of the project were to assess the quality of DAS data recorded in fiber-optic cables from the surface to the total depth, to demonstrate the efficacy of the DAS VSP technology in a deepwater environment, to derisk the use of the technology for future water injection or production monitoring without intervention, and to exploit the velocity information that 3D VSP data provide for evaluating and updating the velocity model. We evaluated the advantages of DAS VSP to reduce costs and intrusiveness, and we determined that high-quality images can be obtained from relatively noisy raw 3D DAS VSP data, as evidenced by the well 1 image, probably the best 3D VSP image we have ever seen. Our results also revealed that the direct arrival traveltimes can be used to assess the quality of an existing velocity model and to invert for an improved velocity model. We identified issues with the DAS acquisition and the processing steps to mitigate them and to handle problems specific to DAS VSP data. We described the steps for conditioning the data before migration, reverse time migration, and postmigration processing to reduce noise artifacts. We outlined a novel first-break picking procedure that works even in the absence of a strong first arrival and a velocity diagnosis method to assess and validate velocity models and velocity updates. Finally, we determined potential applications to 4D monitoring of fluid movement around producer or injector wells, identification of active salt movements, and more accurate imaging and monitoring of complex structures around the wells.

Surface Wave Imaging using Distributed Acoustic Sensing Deployed on Dark Fiber: Moving Beyond High Frequency Noise

“…DAS technology enables acquisition of high-resolution seismological data at frequencies from the kHz to mHz for long distances (tens of km) and at very dense spatial samplings (down to 1 m) in contexts in which the use of conventional sensors is intricate and/or costly (Daley et al, 2016;Becker et al, 2017). DAS is incrementally being adopted in the field of applied geophysics and a variety of studies have demonstrated its suitability for a range of applications such as vertical seismic profiling (Daley et al, 2013;Mateeva et al, 2013;Wu et al, 2015;Wu et al, 2017), time-lapse monitoring of near-surface properties (Dou et al, 2017;Ajo-Franklin et al, 2019), earthquake detection (Lindsey et al, 2017;Ajo-Franklin et al, 2019;Li & Zhan, 2018), and hydrological monitoring (Becker et al, 2017).…”

High‐resolution multi‐component distributed acoustic sensing

“…; Wu et al . ). Although, many examples show that DAS has the potential to provide low‐cost reservoir monitoring (Hornman et al .…”

A field experiment of walkaway distributed acoustic sensing vertical seismic profile in a deep and deviated onshore well in Japan using a fibre optic cable deployed inside coiled tubing

“…; Wu et al . ; Zhan, Kommedal and Nahm ). This DAS‐VSP survey was the first conducted in a deepwater setting.…”

“…The data quality appears to be correlated with the cementation condition, suggesting that quality of the cementing job affects the DAS-VSP data when the behind casing method is adopted. Until the end of 2016, the most advanced DAS-VSP survey was probably the case of the deepwater Mars field in the Gulf of Mexico (Mateeva et al 2013;Wu et al 2015;Zhan, Kommedal and Nahm 2015). This DAS-VSP survey was the first conducted in a deepwater setting.…”