Study On The Controlling Effects Of Salt Rock On Hydrocarbon Accumulation In The Great Campos Basin,South America

Salt basins are widely distributed in the South Atlantic,and they are rich in oil and gas resources,which is currently a hot spot for global oil and gas exploration.Understanding the development characteristics evolution of salt rock structures and their controlling effect on oil and gas accumulation is the focus and difficulty point of the research work in salt basin.Taking the Great Campos Basin on the west coast of the South Atlantic Ocean as example,typical 2-D seismic profile is interpreted to clarify typical salt rock structures and their plane distribution.This paper aims to analyze the control of salt rock on oil and gas accumulation on the basis of the development characteristics of salt rock and the evolution process of salt rock structure in the basin,then the control effect of salt rock deformation on the distribution of turbidite is analyzed.Balanced profile is used to restore the deformaton processes and stages of typical salt structures;Thermal histories both bellow and above the salt rock are then modeled to real quantitatively its influence on source rock maturity and temperature;Finally,key factors that control the hydrocarbon migration and accumulation are clarified based on detailed analysis on typical hydrocarbon reservoirs.Models of dynamic hydrocarbon accumulation model is established and the favorable exploration areas of different types of hydrocarbon reservoirs are predicted.The research shows that:(1)The salt rock structure in the Great Campos Basin has obvious zoning characteristics,which can be divided into the salt extension zone,salt transition zone,and salt extrusion zone from the land to the sea;Formation and evolution of salt rock structures in the basin has gone through three stages: Albian-late Cretaceous,Paleocene-late Oligocene,and Miocene-present.(2)Basin simulation results shows that the differences of the temperature and the maturity of the source rocks in the pre-salt rift period all have a positive correlation with the thickness of the salt rock.(3)Controlling effect of the salt rock deformation on the above turbidite sand includes shield,deflection,confinment and erosion.(4)Favorable exploration area for pre-salt generation and pre-salt reservoir is located in the high part of the pre-salt structure in the basin;Favorable exploration area of pre-salt generation and post-salt reservoir is located in the salt window area where the turbidity sand is developed;Favorable exploration area of post-salt generation and post-salt reservoir is located in the turbidite of mature source rocks in the basin.