Finding New Play Potential In Main Zawtika Development Area, Zawtika Project, Moattama Basin
Zawtika gas field is located over block M-9 in Moattama Basin, Gulf of Moattama, Offshore Myanmar. Through the Pliocene to Pleistocene the Moattama basin was filled with a variety of sediment: mainly from 2 sources; 1) the Irrawaddy River on the northern side of the basin, and 2) the highlands on the eastern side of the basin. Deltaic deposits from the rapid southward progradation of the Irrawaddy delta are found in the basin depocenter. The Tertiary basin fill exceeds 10 km in thickness and is the prospective section in the eastern half of Block M-9. Extensive development of growth faults was due to the rapid deltaic deposition of 6-8 km thick sediment overlaying thick Mid-Miocene shale through the Plio-Pleistocene. These faults restrict to the Sagaing-Shan fault zone and orientate in an ENE-WSW direction. The larger numbers of them can be observed in the eastern half of Block M-9 and performed as normal structural play in this area. Only the structural play of Plio-Pleistocene deltaic sediments, main contributor of Zawtika gas field has been producing biogenic gas since 2014. Apart from conventional structural play, there are also potential plays related to deltaic geological setting such as combination and stratigraphic plays which have not been proven trapping styles by any Zawtika wells. Then, combination and stratigraphic plays are proposed to be additional potential for exploration in main Zawtika area. Zawtika new resource assessment study is aiming to deliver the potential resource of new play type (combination and stratigraphic plays) over existing 3D seismic in main Zawtika area. The study comprises geological setting analysis, play identification, trapping style, seismic special study, prospect identification & evaluation and proposed potential exploration area that conducted study in 2017. Conceptual of new trapping model from new play study can be summarized as 4 trapping styles 1)Canyon fill trap 2)Combination trap of deltaic sediment against canyon 3)Combination trap of channel and 4)invisible channel trap (using channel model) which can be ranked by confidence respectively. The main potential traps for new play study are Canyon fill trap and Combination trap of deltaic sediment against canyon. The first main trapping style is Canyon fill trap which has been interpreted based on geological setting model and using differences in seismic signatures in vertical seismic profile. The contrast of seismic shows lithology differentiation composed of sand-rich, shale-rich and/or alternative sand shale sediment in canyon body. The calibration from offset well result and seismic special study such seismic attribute, delineating the trending of sand-rich sediment are also using to expected to be reservoir potential within body of canyon. The second main trapping style is combination trap of deltaic sediment against canyon body. In this trapping style, muddy units within canyon body can act as lateral seal to trap gas in deltaic sediment that against to canyon body. The hydrocarbon exploration related to canyon also requires insight understanding of trapping styles of Canyon fill trap and Combination trap of deltaic sediment against canyon by using geological model, seismic feature & attribute and AVO study to increase the level of confidence for interpretation and evaluation. Eventually, two new play prospects are planned to test and evaluated in near future, both Canyon fill trap and Combination trap of deltaic sediment against canyon while other two additional traps related to channel will be ranked and realized. The new play potentials in main Zawtika area with economic findings will be potentially support sustainability and future growth of Zawtika development field.
AAPG Datapages/Search and Discovery Article #90331©2018 AAPG Asia Pacific Region GTW, Back to the Future – The Past and Future of Oil and Gas Production in the Asia Pacific Region, Bangkok, Thailand, September 26-27, 2018