Study of mechanism for petroleum generation, migration and accumulation, block 04-3, Nam Con Son basin

Abstract

Exploration drilling and production results in block 04-3 confirmed oil and gas potential on the Thien Ung-Mang Cau prospect. The remaining potential prospects that are not drilled should continue to be studied and evaluated for petroleum potential. The purpose of this paper is to integrate and digitize the data from results of facies and environment studies, petrographic characteristics, and geochemical data to simulate the petroleum system model to determine the processes of generation, migration, the mechanism for hydrocarbon trap charging, and distribution of petroleum accumulations. Based on the reality of successful oil and gas discovery and exploration in block 04-3, the process of building a 3D petroleum system model is settled and consists of four main steps: input data combined with boundary conditions, running simulations, assess model results and adjusting data. Utilizing studying the role and contribution of hydrocarbon composition in the source rock, the migration direction, the paper clarifying the generation process, the trend of distribution, and the assessment of the hydrocarbon migration and charging mechanism in block 04-3 area. The results of digitalization of data on the geochemical analysis of effective source rock, building facies modeling and the sedimentary environment, boundary conditions models, and 1D models, the 3D petroleum system model has successfully simulated. The results allow to draw following findings: there are two formations of source rock Oligocene (H-150) and lower Miocene (H-80), in which the source rock belongs to the Oligocene sediment section at 16.5 Ma in the oil generation phase and 10.5 Ma - 5 Ma mostly in the late oil to wet gas and condensate production phases, this source rock plays a crucial role in hydrocarbon generation; hydrocarbon accumulations formed in the suitable trap mechanisms within Oligocene and Miocene periods in the with channel deposits, deltaic (fluvio-deltaic) environments, preserved in stable conditions until hydrocarbon accumulation established in which contribution mainly from Oligocene-aged claystone source rocks; Two potential accumulation groups existence in block 04-3 also revealed: the Hai Au structure and the Hoang Hac structure with the Oligocene, lower Miocene, and middle Miocene reservoirs. The results of the model will be used to propose the allocation of exploration wells for evaluating the remaining oil and gas potential accumulations in block 04-3. Furthermore, the study not only focuses on evaluating the effective source rocks, determination of the main hydrocarbon charging area, the migration process and mechanism for the petroleum-filled trap but also clarify the role of effective source rock sequences for providing hydrocarbon of potential petroleum accumulation in the study area.