DAS VSP Acquisition Through Coiled Tubing Fiber-Optic Cable

Abstract

Summary Coiled tubing (CT) is a very long metal tubing on a drum that is used for intervention services as well as a conveyance method for logging tools, typically a production logging toolstring, when a well is highly deviated or horizontal. The conventional wireline method would not be able to move the toolstring down to the bottom of the well with gravity. Traditionally, there is no relationship between CT services and borehole seismic logging because CT services are mainly run in highly deviated cased hole development wells, whereas borehole seismic data is usually acquired in vertical or less deviated openhole exploration wells. However, real-time downhole CT logging services introduced fiber-optic cable inside the CT, which is used for telemetry communication originally with two multimode fiber (MMFs). Adding another MMF enabled distributed temperature sensing (DTS) while-CT-logging service. This situation created the possibility of borehole seismic acquisition-while-CT service by adding a single-mode fiber (SMF) in the fiber-optic cable. Called distributed acoustic sensing (DAS) vertical seismic profile- (VSP-) while-CT service, this is a new way of acquiring VSPs.