Features of the Complex Fault Block Reservoirs in Biyang Depression and Exploration Techniques

Favorite conditions for oil enrichment exist in the northern slope zone of Biyang depression.Reservoir types and distribution are under the control of fault systems,occurrence of structure nose,sandbody distribution and the relationship between the above three.In the west,fault nose is the main reservoir type in Gucheng oilfield,while in the east,there exist mainly fault block,fault&lithologic reservoirs.Faults formed after large-scale mi-gration of hydrocarbon and the vertical span of oil-bear-ing horizons are large in each oilfield with the major oil layers crowded together and consistent with each other in different fault blocks;from south to north,buried depth of oil layers gets shallower and crude oil properties poor-er;oil layers are thin and mostly are medium to thin layers;oil-bearing zones in a single fault nose or fault block are narrow and there exist several separate oil and water systems.The key to exploration is accurately locat-ing fracture system s and the distribution in space.Appli-cation of the rapidly developing technologies such as3-D seismic exploration,directional drilling and protection of wellbore and oil -bearing layers can enlarge benefits of exploration of complex fault noses and blocks.