Hailar Basin Cap Distribution And Fault Sealing Assessment

As a large deposit basin of DaQing exploration area, Hailaer basin has been still an important area for oil and gas exploration . It has made greatly achievements for many years and fully opens up the bright prospects of oil and gas exploration. However, the facts proved that faults existed large-scale and developed in every depression in Hailaer basin, and destroyed the integrality of caprocks, and complicated migration and accumulation law of oil and gas pools. Because exploration extent of Hailaer basin is low and research to oil and gas preserve condition also is weak, research to distribution characters, sealing of caprocks and faults sealing and their evolution histories is very significant.The paper takes Wuerxun and Beier depression for examples. First, based on collecting comprehensively information of geology well loggings earthquake and tests, the paper discusses sealing abilities of caprocks from macroscopical distribution and microcosmic sealing abilities, evaluates comprehensively sealing abilities of caprocks. Second, through analysing to the basin' s structure evolution history and faults developing characters, the paper mainly analyses activity history and sealing principle of faults, and applies logic information law to evaluate faults sealing of different formation. Last, based on analysis of present distribution characters of caprocks and faults and fault sealing, the paper discusses deeply sealing effectiveness of caprocks and restores fault sealing evolution histories, and further expounds controlling effect to oil and gas of sealing condition of caprocks.The paper thinks that: The 1st section of Damoguaihe formation mudstone caprock is regional caprock of Hailaer basin, its sealing ability and quality are better than those of the 1st section of Nantun formation and the 1st section of Yimin formation mudstone caprock; Considering fault sealing in Wuerxun and Beier depression, the paper concludes that fault sealing of Nantun formation is better than that of Damoguaihe formation, the latter is better than that of Tongbomiao formation; Fault sealing will be gradually well from ancient times to the present; The 1st section of Damoguaihe formation mudstone caprock contrails oil and gas distribution in all basin, and can effectively seal oil and gas of lower formation and form oil and gas pools; Forming of many kinds of traps is controlled by fault sealing or open, it is summed up that there are four kinds of oil and gas deposits, fault block deposit is majority among them.