Through-Drill Pipe Logging and Formation Sampling in Deviated and Risky Wells

Abstract

Drilling wells in complex geological structures from offshore platforms, or onshore in areas with land access restrictions often creates complex S-shaped wells. In many such wells, high-angle doglegs cause problems with wireline key-seating, thus restricting reservoir access. When Logging While Drilling (LWD) data acquisition is not an option and Pipe-Conveyed Logging (PCL) is discarded because of its risky and time-consuming nature, many wells could end up without critical Formation evaluation data.

To overcome reservoir access challenges in the Sirikit Field in Thailand, a Through-Drill pipe Logging (TDL) technique has recently been introduced to complete formation evaluation. This method safely and effectively overcomes the complex well trajectories and associated wireline conveyance problems, such as key-seating. Slim 2.25" OD logging tools including Triple Combo (TC), Quad Combo (QC) and formation pressure tester and fluid sampler are deployed on wireline through open-ended drill pipe into open-hole without difficulties and with full well control maintained at all times.

A standard TDL operating procedure has been developed between wireline and drilling crews, allowing for safe and fast operations. The driller is able to have well control, with pipe being reciprocated regularly. Typically the drill pipe is run with a reamer shoe to allow borehole cleanout operations in the same run. The TDL deployement method is now a key component in the standard decision tree for data acquisition strategy in Sirikit Field and it has been successfully introduced in the Sirikit Field in May 2016. Since then, a total of 59 runs have been performed in 31 wells where wireline reservoir access problems were encountered, saving an estimated 1,240 hours of combined rig time not counting any potential wireline fishing jobs that would likely have occurred. A near 100% success rate is maintained, measured by reaching well TD and acquiring all desired wireline data. Petro physicist and geologists are no longer left without the crucial formation evaluation data they require for successful reservoir management.

This paper present a case study that clearly demonstrates that the TDL deployment technique can be very effective in providing safe and efficient wireline access to reservoir sections in S-shaped wells with risky wellbore conditions, where high-angle doglegs and key-seating would otherwise have restricted the ability to obtain Formation evaluation log data and fluid samples.