Abstract
To develop a field with combination structural and stratigraphic trap style is always challenging, especially with trap uncertainties that are coupled with limited exploration and appraisal wells. The potential production shortfall or non cost effective development plan would be an issue if the number and locations of the wells are not carefully selected. Thus, a comprehensive reservoir modeling study, both static and dynamic modeling was designed and instituted to integrate all available information and geological concept.
In the Muda South Central (MSC), which will be discussed further in this paper, structural re-mapping was conducted to refine the trap and structural style. However, the plunging nose structural styles do not have a closing contour to the north of the field, which requires interpretive arbitrary boundary to isolate the compartment and to limit the field boundary. The nearby field in the northern part has a four way dip closure which proves to have a different fluid system with the studied area. Concurrently, a geological facies modeling study was generated using regional trend knowledge and guided by seismic attribute qualitatively. Reservoir trend direction has played an important role in hydrocarbon trapping. The high uncertainty of reservoir presence was assessed by including inputs of low and high extremes sand-shale-ratio in facies modeling exercise for the purpose of capturing reservoir uncertainty.
In dynamic simulation, Simulation Opportunity Index weighted with Gas Initially In Place (GIIP) map is considered to identify sweet spot location. This enables the subsurface team to optimize the number of development well and the placement of the well at the ‘sweet spot's location. Water and sand production prediction is taken into the consideration to minimize the impact to well performance.
Subsurface uncertainty analyses were performed which includes sand distribution, fluid contact in vertical and lateral extension, rock & fluid properties, aquifer strength and well performance. The uncertainty of the number of development wells was anticipated by performing multiple simulations for low and high case. The model is intended to be used as a guidance to subsurface team for decision making during the development drilling campaign.
