Simple Model of HC Migration Generate oil and gas at lower left HCs ‘percolate’ into porous interval (white) Trap A fills with oil and gas – gas displaces oil Trap B fills with spilled oil and gas Seal at B will only hold a certain thickness of gas At trap B – gas leaks while oil spills Trap C Slide 32 This animation shows output from a HC migration software package Buoyancy is the driving mechanism and rock properties have to be defined In this example, Trap A has a very good seal – it has early oil fill which is displaced by late gas Trap B has a good seal for oil but allows gas to leak once the gas thickness exceeds a critical value Trap B maintains an oil leg – the gas can not displace all the oil since it leaks through the top seal Excess oil in Trap B (with some dissolved gas) spills into Trap C This is a 2-D model to help show conceptually the types of HC migration that could occur Rock properties can be varied (e.g., stronger to weaker seals, different source rock properties) We can build 3-D migration models as well, but often we do not have adequate data to constrain the results We model different scenarios, but can not say which is correct pre-drill Trap B Migration Path Of Spilled Oil Spillage of Excess Gas “Gas separator” Trap A Traps with unlimited charge Source Generating HCs Courtesy of ExxonMobil L12 – Data Analysis