The recent infill wells of MDE were drilled and completed with the most complicated architecture in CPOC. They were designed with high inclination reaching almost 87 degree and 2.6 ERD ratio in order to optimize hydrocarbon recovery from multi-stacked reservoirs within the area. The study, driven by cost effective initiatives, compared wireline tractor conveyed perforation (run in normal and reverse deployment modes) and coiled tubing conveyed perforation (again, run in normal and reverse deployment modes). The aim of this study is to provide the most efficient technique to achieve maximum hydrocarbon returns with low operational costs and minimum risks. The scope of this study includes consideration of well test requirement and net over gross ratio of perforation interval.
Four (4) options are feasible to complete these high inclination and long departure wells: wireline tractor-conveyed perforation (run in normal and reverse deploy modes); and coiled tubing-conveyed perforation (run in normal and reverse deploy modes). The analysis includes several factors such as different rig-up height, perforation depth accuracy, perforation flexibility, operation time, and tool requirement. Generally, the job executions begin by rigging up the perforating gun into wireline or coiled tubing conveyance, then running in hole to designated target depths.
The wireline tractor with reverse deployment and multiple-firing system was the chosen method, deployed for the first time in slim hole, high inclination and long departure wells within Joint Development Area (JDA), Gulf of Thailand. This conveyance method proved to provide a 68% reduction in numbers of runs, with cost reductions of 25% and 50% in operating day and operating costs respectively. Perforating operations in all three wells were successfully completed with 269 meters total perforation length. The tractor operated for a total distance of 94 kilometers which is considered as the longest tractor marathon in a campaign worldwide.
The utilization of tractors for this campaign is considered as a record breaking for the operators and contractors. As a result, the wells have been able to deliver the gas as expected and fulfill the nomination to buyer demand.