L53-DD, On-Shore Thailand a Case Study of Integrated Geoscience to Engineering Approach Improving Reserve Estimation and Field Development Planning

The study emphasized on a collaborative work across various domains to improve reserve estimation utilizing integrated analysis from geological understanding, seismic interpretation, petrophysical log to sampled pressure and production data. A cross-disciplined approach was tailored for this complex marginal field and it included a fast loop full-field reservoir modeling and simulation to delineate the reservoir characteristics in a timely manner. The study improves the confidence level in reserve estimation of the field with a range of 30-35% primary recovery factor interpreted across different sands which is in line with other publications that in a typical Gulf of Thailand oil reservoir, in the presence of a strong water drive, the most likely primary recovery factor is between 18-40%, depending on the thickness of the oil column, bottom water versus edge water and the presence of a gas cap. The study helps to drive real field decision making for upcoming drilling campaigns to further improve the economic life of the field. This paper presents a fit-for-purpose reservoir modeling while drilling approach demonstrating how the company used newly drilled well data to validate the reservoir model and to drive new decisions for field development planning. The industry has limited published case studies on medium to heavy oil (19 to 25 degree API) with strong aquifer support in the region of onshore Thailand. This case study presents an approach in addressing multiple challenges faced to unlock the high oil potential of the region. In summary, a cross-disciplined, fit-for-purpose and practical approach using latest available commercial technology enabled real-field decisions being made timely and accurately. Similar approach will be undertaken in other fields of the company in the region.