Discriminatory method and its application of oil-gas migrating direction in fault-sand-body configuration

Key words:  fault-sand-body configuration  oil-gas  lateral migration  vertical migration  discriminatory method  Nanpu Depression  Dongying Formation

Abstract:

In order to study the oil-gas distribution patterns in lower generation-upper accumulation source rock-reservoir-cap rocks in oil-gas bearing basins, a set of discriminating methods for oi-gas migrating direction in fault-sand-body configuration were established. The methods were derived based on necessary conditions and mechanisms of oil-gas migrating both vertically along faults and laterally along sand bodies, and by comparison of relative sizes of displacement pressures in fault filler and sand bodies. The new methods were then used to determine the vertical and horizontal directions of oil-gas migration in 7 transport faults of 5 typical blocks in Nanpu Depression, and 53 sand layers in Dongying Formation. The result show that in 53 sand layers of Dongying formation,the displacement pressure of 35 sand layers is less than that of fault filler, where oil-gas migrates laterally along sand layers; oil-gas drilling is oil layer or oil-water layer. The displacement pressure of the rest 18 sand layers is larger than that of fault filler,where oil-gas migrates vertically along fault and oil-gas drilling is water layer or dry layer. The results are coincident with known well logs, and suggest that the method is feasible to be applied in discrimination of oil-gas migrating vertically along fault or laterally along sand-bodies in fault-sand-body configuration.