Wuerxun Depression Hydrocarbon Accumulation Mechanism Of The Southern Section Of The Main Controlling Factors

On the basis of study lo structure and sedimentary background of Wuerxu depressions, conditions of source rocks, reservoir rocks, cap rocks, oil or gas accumulation and migration were studied completely and systematically in the areas. Using oil or gas data of drilling and displaying , types and distribution of reservoirs in Wuerxun deperession of k1n2 are summarizd .Three kinds of oil or gas reservoirs are found, they are structural reservoirs, lithological reservoirs and structural-lithological reservoirs. Most of oil or gas reservoirs distribute in Surennuoer structural zone and Bayantala structural zone in plane. But the number of oil or gas reservoirs in Surennuoer structural zone is more than that in Bayantala structural zone. Considering all kinds of accumulation conditions and distribution of reservoirs, main factors controlling oil or gas accumulation and distribution are time and space matching relation between source rock and cap rock, sedimentary environment, faults and traps. On the basis of generation and expulsion hydrocarbon history of source rock, seal formation history of cap rock, formation history of trap, active history of fault, oil or gas accumulation period using illite's ages, main oil or gas accumulation period was determined to be from the end of Yimin formation to the early of Qingyuangang formation. By the types of oil or gas reservoirs, three kinds of oil or gas accumulation models fit to Wuerxun depression. They are the model of oil or gas migrating and accumulating in sandstone lens or fracture traps of source rock, the model of oil or gas accumulating in fault-block or fault-screened traps through vertical migration, the model of oil or gas accumulating in structural-lithological traps migrating laterally in short instance through sandrock. Based on it, favorable exploration areas in Wuerxun depression are predicted. The most favorable exploration areas of ktn2 are Surennuoer structural zone and huangqimiao structural zone.The more favorable exploration areas are Tongbomiao structural zone, wudong slope zone, wuxi fault zone, vvuzhong structural zone and Bayantala structural zone. Huang yi-l,Suwu-7 and Suba-9 traps ofk1p2 are considered to be the most favorable traps for oil or gas to be drilled.