Abstract
The Tertiary Phitsanulok basin is well known for the Sirikit field which is the largest onshore oil field in Thailand. However, in the northern part of the basin, no oil field was discovered by previous operators who drilled some 12 vertical wildcats based on 2D seismic data in the 1980s. Geology of the basin is similar to that in the Gulf of Thailand. Its main reservoirs are lower Miocene fluvial sandstones which are thin bedded, poorly connected and compartmentalized by many faults. Moeco, who has produced oil and gas in the Gulf as a non-operator for 30 years, has applied the technologies used in the Gulf, and successfully discovered oil, and is currently conducting long term production testing in the onshore area. To increase the wildcat success ratio and to maximize the number of stacked pays discovered in fluvial sediments, crucial technologies employed include precise 3D seismic interpretation and drilling of deviated wells close to fault planes. Multiple stacked oil zones were discovered particularly in fault blocks sealed updip by normal faults that dip toward to the basin center. Moeco also has utilized technologies of slim well design, batch drilling and comingled oil production through 2-7/8” tubing to reduce drilling and operation cost and to make relatively small oil accumulations commercial.
