Qijia - Gu Area Fuyang Reservoir Reservoir Evaluation

Study area, Qijia-Gulong region, bestride the two first grade tectonic units of western paleo-inclinoform and Qijia-Gulong depression, its main part located in Qijia-Gulong depression. The period of target layer, Fu-Yang oil-bearing layer (the memberS and 4 of Quantou formation) deposited was coincide with accelerated subsided period in down-warped stage of Songliao basin evolution process.Controlled by north and west depositional system, Fu-Yang oil-bearing layer consists of delta distributary plain and delta front sub-facies depsits of delta depositonal system, widely distributed various distributary channel sand deposits come into being favorable reservoir space. Upwardly, The thick dark mudstone of member 1 of Qingshankou formation can provide plenteous oil source for Fu-Yang oil-bearing layer, A large number of formal faults developed in T2 structural layer can provide path for oil migration.Analysis results of a number of testing data indicated that: sandstone reservoir of Fu-Yang oil-bearing layer has lower composition maturity, mainly are feldspathic arenite and lithic arkose. Due to the lower composition maturity and long buried history, sandstone experienced relative intense diagensis, diagensis type mainly are compaction, cementation and dissolution. The diagensis sequence can be divided into 5 associations. The diagensis stage is during late diagenetic A and B period.Lapidofacies of sandstone reservoir can be divided into calcite cementation, illite filling, quartz overgrowth and dissolution four lapidofacies types, which have different distribution rules. 5 pore types of sandstone reservoir, interparticle pore, innerparticle pore, interstitial content pore , fracture pore and dissolution pore, can be recognized. Reservoirs exist serious phenomena of velocity, water, acid, alkali and salt sensitivity. Diagensis greatly affected the porosity-permeability, sensitivity and oil-bearing ability, which characterize by the more intense diagensis, worse porosity- permeability and lower oil-bearing grade with the deeper burial.Reservoirs type mainly are IV2, secondly are III2> 112, its peak semidiameter of pore-throat is between 0.13urn and l.Sum is favorable reservoir, which developed area is the advantageous region located in surrounding depression, and turned into potential area for Fu-Yang oil-bearing layer exploration, predicted reserves about 7~8X 108t.Economic technologicial evaluation results indicated that under present technology, Fu-Yang oil-bearing layer of Bayanchagan and Longxi area have exploitation economy benefit.