Abstract
Zawtika Project is an offshore gas field located in the Gulf of Moattama, Myanmar with water depth ranges from 120 meters to 160 meters. PTTEPI has operated Zawtika field and brought it to production since 2014 with conventional wellhead platforms (CWP) development. The future prospects are expected to be smaller gas reservoirs which are not commercially developed with CWP. Thus, a minimum facilty platform concept study had been initiated after CWP cannot be economically justified to develop and maintain gas production plateau.
The basic engineering study was conducted on the selected wellhead platform options namely Zawtika optimized conventional wellhead platform (ZOCP) and Zawtika minimum facility platform (ZMFP). These platform types will be chosen for EPCI based on the size of the candidate prospects after the post-appraisal well result is confirmed.
ZOCP is merely a conventional wellhead platform with partial design optimization. On the other hand, ZMFP is a true minimum facility platform. This paper will focus on this type of platform.
ZMFP capacity is reduced to match with the target prospects at 90 MMSCFD gas production. The facilities equipment and intra-field sealine are also reviewed and optimized. ZMFP is expected to reduce the CAPEX approximate up to 20% from (1) minimized well slots (2) commingled the flowlines (3) sweet gas material compatible selection. The unique design of ZMFP is the power supply comes from 100% solar power which is a new implementing concept.
Estimated of the base weight of ZMFP is 17% lower than CWP leading to estimated CAPEX reduction almost 20% compared with CWP. However, due to the stability of platform under the water depth of Zawtika field condition makes the wellhead platform design to be a 4-legged jacket. Small improvement can be done at the jacket which is about 65% of the total CAPEX.
Then an economic evaluation is carried out to compare the NPV of the existing platform design with the improved ZMFP, it found that NPV improve significantly almost 15 %. With the lowering down of the CAPEX, at this stage ZMFP design currently enables 3 sub-commercial prospects to be economically developed. ZMFP design is already selected to implement with the coming Zawtika phase 1D development for 3 wellhead platforms and now it is under EPCI preparation.
Zawtika minimum facility platform demonstrates PTTEPI aims to maximize the resource recovery of the field by developing and monetizing sub-commercial reservoirs. With the above-mentioned objective, a new platform is engineered and designed to sacrifices some options down to its fit-for-purpose facility yet maintain the integrity and environmental friendly designs.
