| Under the premise of migration force conditions, fluid properties in certain, oil and gas migration is controlled by the migration systems. The current connotation and the type of the oil and gas migration systems in research is different.which mainly concentrated in the high porosity and permeability sand body, unconformity,fault and any two or all of the complex migration system. There are two problems in research:Because there are oil and gas reservoirs in source rocks, source rocks should be fully considered;The type division of migration systems mainly stay at the macro level.In fact, under the premise of migration force conditions in certain, when there are differences in conducting performance of transporting medium, the amount of migrating oil and gas is different. the study of the differences of the conducting properties of the conducting medium should be strengthened.This paper study on bohai bay basin in jiyang depression tertiary strata as the research object, through the core and slice observation, overburden pressure the porosity and permeability determination and comprehensive use of rock mechanics analysis and experimental method,, reached the following conclusion:(1) Mudstone migration performance evaluationIn mudstone,the permeability in direction of the parallel level is higher than that of vertical level direction, the ratio of the two is1.31-29.14。The permeability of mudstone with fracture is far greater than that without fracture.The ratio of the two is100-48000. Sandstone migration performance evaluationIn sandstone,the permeability in direction of the parallel level is higher than that of vertical level direction, the ratio of the two is1.12～9.32。The permeability of sandstone with fracture is far greater than that without fracture.The ratio of the two is5～1000.(2) Fault migration performance evaluationThe migration and seal performance depends on the maintain degree of the fault and fracture. The ability of the fault and fracture to maintain depends on the stage of mechanical evolution.In the rupture stage which is stronger in rigid and the stage of elastic-plastic compression, the fracture caused by fault activity is not easy to be closed,the migration performance depends on the migration performance of the fracture of mudstone and sandstone.In the compaction stage which is stronger in plasticity, the fracture caused by fault activity is easy to be closed, the migration performance depends on the migration performance of the pore of mudstone and sandstone.(3) The type division of the oil and gas migration systemsAccording with the order from the optimal to bad of migration performance, namely fault>fracture>unconformity> strata,the migration systems is divided into four types: unconformity-strata.migration.systems,fracture-unconformity-strata-migration-systems,fau lt-unconformity-strata-migration systems and fault-fracture-unconformity-strata migration systems.(4) The distribution of various migration systemsJiyang depression develops4types of migration system.Minghuazhen group mainly developped unconformity-strata migration systems, fault-unconformity-strata migration systems. Guantao group-sand four upper group mainly developped unconformity-strata migration-systems.fracture-unconformity-strata-migration-systems,fault-unconformity-stra ta migration systems and fault-fracture-unconformity-strata migration systems. |
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