The Sirikit field is a mature reservoir located in the Phitsanulok Basin in north-central Thailand. The field produced first oil in late 1981. Typical logging programs include a complete set of openhole (OH) logging suites such as a triple combo, including gamma ray-neutron-density-resistivity, or quad combo including gamma ray-neutron-density-sonic-resistivity. The reservoir production and injection are carried out with commingled completion. Therefore, wireline formation testing, and sampling tools are usually included for acquisition.

Development wells with highly deviated trajectories pose challenges to conventional wireline logging (WL) operations, especially in deep wells exceeding 3,000m. In sections with high dogleg severity, the tools are prone to sticking, and the cable can become key-seated due to hole conditions, deviation, washouts or caving.

Log data is a vital component for studying geological complexity, completion and production planning. Therefore, there is a need for an alternative method to convey WL tools to reach the bottom of the hole. In 2015, an alternative conveyance method called "through drillpipe logging" (TDL) was proposed to mitigate the risk of WL tools sticking or hanging up in an openhole environment. This method uses a slim-chassis, 2.25 in. outer diameter (OD), WL logging suite that enables the tool to be run through the drillpipe. The first TDL job was trialed in Thailand in May, 2016 as the second run after the WL run hung up. This TDL run hosted a full triple-combo suite and WL formation testing tools, which reached total depth (TD) while overcoming hole-condition issues that had been experienced during the first run. Following this successful log run, the TDL has become the preferred contingency planning option to support WL operations in challenging wells. To date, a total of 64 jobs, including triple combo (TC), quad combo (QC), formation testing & sampling (FTS) and cross-dipole sonic (CDS) have been executed successfully with less operating time than conventional contingency processes involving wiper trips, tool pushing, or pipe conveyed logging. This track record confirms that TDL provides a fit-for-purpose solution for logging in challenging conditions.

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