STAVANGER, Norway – The Z-Line, a gravity-deployed carbon-composite cable, was used to acquire distributed temperature and distributed acoustic fiber-optic data during a commercial well intervention, Ziebel AS has announced.
The Z-Line made its inaugural run for a major operator offshore Norway. The system accessed a platform well to a depth of 9,684 ft (2,951 m) with standard wireline-type gravity deployment and dry sealing pressure control equipment. All mechanical requirements of the line functioned successfully, and distributed fiber-optic data was acquired for the operator.
Z-Line builds upon the Z-System carbon composite technology. The key difference between the two is that the new cable has a smaller wireline footprint, and, being gravity-deployed, has a typically shorter intervention time per well.
The new cable is a 3/16 in. (4.8 mm) diameter carbon composite line with embedded optical fibers at its core. This enables distributed temperature sensing and distributed acoustic sensing to be performed along the full length of the line. In addition, Ziebel’s optical point pressure and temperature sensors are contained within the bottomhole assembly (BHA), along with a connection to enable standard memory logging tools to be run below the BHA. The rig-up and footprint are similar to that of a standard wireline cased-hole setup, although the distributed measurement acquisition method does differ in that it is carried out with the line parked stationary in the well.
The carbon composite material enables the line to have an extremely high strength-to-weight ratio, with a breaking strength of 6,600 lbs (3,000 kg). The outer finish makes for effective sealing, and the low friction coefficient to steel plus the relative stiffness of the line gives it increased ability to reach into deviated wells. In addition, the low friction reduces the abrasion and tubing wear associated with standard wireline or slickline runs.
Applications that can be addressed with the service include:
- Well Integrity, producers: annular leak detection source and fluid migration behind casing detection.
- Well Integrity, injectors: verify that no unwanted injection occurs into the overburden.
- P&A: provide information to help optimize the number of plugs and to decide where they should be set, to determine where to safely cut casing strings, and to verify wellbore integrity.
- Production optimization: determine gas lift settings required for a stable flow regime and the optimal gas injection volume/production ratio. Verify that GLVs operate in the right sequence and that dummy valves are not leaking.