Thailand Joint-Development Project Delivers MWD/LWD Benefits
Authors: Carpenter Chris 
Published: January 2019

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 191054, “Thailand Joint-Development Project Delivers 200°C MWD/LWD Triple Combination: Eliminating Wireline, Driving World-Class Efficiency, and Slashing Days Per Well,” by T. Kleawyothatis, SPE, and J. Pruimboom, SPE, Weatherford, and S. Dendandome, SPE, N. Pisarnbut, SPE, and P. Thipmongkolsilp, SPE, Chevron, prepared for the 2018 IADC/SPE Asia Pacific Drilling Technology Conference, Bangkok, 13–14 March. The paper has not been peer reviewed.
A joint-development project has delivered a high-temperature measurement-while-drilling/logging-while-drilling (MWD/LWD) suite rated for 200°C. Results to date are compared with previous performance in the Gulf of Thailand (GoT). The new suite required a complete redesign of printed circuit board (PCB) electronics in order to meet the temperature-qualification criteria of 200 hours at 200°C with a survivability of 210°C for 4 hours.
Background
When the joint development of extreme-high-temperature tools began in May 2014, the goal of the collaboration was to eliminate wireline in wells with temperatures over 175°C. Historically, the need for wireline was driven by the requirement to identify hydrocarbons, measure reservoir properties, and book reserves in high-temperature wells; this was accomplished by using a wireline string consisting of gamma ray (GR), resistivity, formation- density, and neutron-porosity sensors. Because of the 175°C temperature limits of the available LWD technology at that time, there was no viable option to log these wells while drilling. This resulted in valuable rig time spent on additional trips to change out bottomhole assemblies (BHAs), mitigate temperatures, and run wireline to gather this data. This also increased the exposure to nonproductive-time (NPT) events, stuck wireline tools, or loss of data if these tools did not reach bottom. Thus, the requirement arose to log these wells while drilling to reduce days per well and improve data collection. To this end, the joint development of extreme-temperature LWD tools was initiated and staged in two phases.
Phase 1 was the development of a 200°C-rated mud-pulse telemetry system, a bore- and annular-pressure-while-drilling tool, a GR tool, and a thermal neutron porosity tool. These were jointly developed within a 9-month period. Thirty-two wells were drilled with these tools with zero NPT and only two minor failures in secondary sensors before commercialization.
A second phase of the development was endorsed to develop bulk-density and resistivity sensors to complete the triple-combo logging suite. This would ultimately deliver the principal objective of eliminating the need for running wireline. Phase 2 began in March 2015 and was given an 18-month window to deliver final products. The sensors required a complete re-design of all electronics to meet the temperature-qualification criteria outlined previously. Ten PCBs were designed and tested.
The next step involved a thermal-vibration qualification by building up individual inserts, strapping them on a vibration table, and subjecting them to 15–20 Gs of random vibration while heated to 200°C. This harsh testing identified more modifications and re-designs needed until all inserts met these criteria. After completion of all testing, five complete prototypes were built and delivered on time and on budget in September 2016 to begin field trials.