High Performance Tractor Conveyance with Integrated Telemetry Capability Enables Real-Time Production Logging Acquisition While Tractoring to the World's Most Extreme Extended Reach Wells
Authors: Murchie S. W. , Correia G. , Tabrizi P. N. , Arnaly G. , Shvedikov A. 
Published: October 2023

An operator in UAE is redeveloping a giant offshore field by drilling and completing extreme extended reach wells from four environmental islands. This unique, efficient, and sustainable methodology is enabling accelerated field development, optimized reservoir access and drainage via less wells, and increased oil recovery. Well designs with Measured Depth (MD) to True Vertical Depth (TVD) ratios up to 4.5 are resulting in wells of up to 50,000 ft MD having horizontal laterals of more than 33,000 ft. Following completion, diagnostic logging surveys are required to provide production / injection profile and zonal contribution across the entire lateral section for life-of-well performance management.

The drilling and completion of horizontal and tortuous wells has been ongoing since the nineties, spurred by the growth of offshore field developments. Technology advancements have enabled ever increasing well depth and lateral lengths to be achieved, with extended reach drilling (ERD) providing Maximum Reservoir Contact (MRC) to optimize well productivity and drainage. World record MD and lateral lengths set last decade are now being broken in the UAE, with yet further records being pursued. The ability to successfully intervene in these wells for surveillance, diagnostic or mechanical services has until now proved challenging. Friction between conventional deployment systems and completion tubulars are preventing the desired target depth being reached as electric-line cable safe working load limits being exceeded. Reliable real-time tractor control and logging tool data transmission is also challenging as cable lengths increase.

New composite rod and coated cable construction are now enabling the physical deployment of toolstrings along the extent of these extreme laterals, this through a combination of improved strength-to-weight ratio, reduced friction, torque-balanced armor design, and efficient surface pressure control systems, all while maintaining electrical capacity. Enabling real-time acquisition of logging data during tractor-conveyed down passes is vital to achieving high-quality production or injection diagnostics. High quality high bandwidth acquisition tools are being coupled with advanced tractors having superior high bandwidth modem technology with integrated telemetry capability. This enables downhole integration of passenger tool data and simultaneous multiplexed transmission with tractor data to surface, the passenger tool data then fed to the relevant log acquisition system. This digital handling avoids signal deterioration through long electric-line cables or alterations due to electric noise typically experienced with long cables, particularly so during Logging While Tractoring (LWT) acquisition. Furthermore, maintaining advanced real-time tractor functionality and control is enabling stable optimal tractor speeds to be established in-well and maintained during down pass acquisition across multi flow or injection rates, this adding further to the quality of logging data being acquired.

Tractor upper and lower tension/compression data and a range of tractor diagnostics information further enhance the LWT operational awareness, control, and efficiency, and ultimately extend the reach to record depths while acquiring quality data across the lateral.