Study On Sedimentary Characteristics Of Saertu Reservoir In West Clinoform Region Of Northern Songliao Basin

This paper exerting the theories of sedimentology and reservoir geology etc, and comprehensively applying geology, logging, seism and core data, analysis depositional system types and sedimentary features of Saertu Reservoir in west clinoform region of Songliao Basin, studies genetic types of reservoir and its control factors, and researches the oiliness characteristics and its affecting factors. Based on the sedimentary microfacies study of stress blocks (Jiang55 well field and Jiang 37 well field), this article dissects the reservoir category of main oil-bearing, sums up the reservoir forming modeling in this area, and optimizes the beneficial oil and gas prolific zone in this area.At the time of Yaojia Formation posses there are two main depositional system-Qiqihaer depositional system and Yingtai depositional system, local western area exists minor axis matter source. Under water distributary channel, under water interdistributary, mouth bar and distal bar which develop on the delta front is the main depositional system types in this area. However, in the deposit period of Nenjiang Formation, the Songliao Basion suffered widely invasion of lake, the affection of southwestern depositional system and Qiqihaer depositional system obviously abate, at the same time, the lateral branch of northern depositional system access the work area from northeast, and form the dististele deposition of delta front extra-fan in northeast area, and deveolop mere lake-semi-deep lake sediments in other area.The main reservoir rock in the study area are banding delta under water distributary channel, shore lake-meare sand bar and sand sheet, the main rock types are argillaceous siltstone and siltstone. Accumulate capability are remarkably affected by diagenesis, shallow bury, low compaction and feeble diagenesis are the dominant factors of forming high porosity and high permeability. Argillaceous cement and carbonate cement have bound affection to reservoir aeolotropy, but affect lightly.The reservoir forming feature in this area is: sediment microfacies control reservoir, migration and conservation petroleum. Micorfacies category and distribution determine whether the reservoir is superior or inferior, and migration condition and conservation condition is the key to form reservoir. As underwater distributary channel and mouth bar can easily seize oil and gas by means of uncomformable surface and fault, so their reservoir physical property and horizontal communication are fine, but their conserve capacity is evidently affected by layer modality and trap amplitude, so they can be easily washed. Distal bar and under water over bank sandbar distribute isolate and confine, although the probability of seizing oil and gas is relative small by means of fault and uncomformable surface, but the conserve condition of mudstone cap formation is fine, once possess migration condition and accumulation condition, the condition of forming and preserving reservoir is benefit on the contrary.West outskirt of eastern delta in Jiangqiao Area, sedimentary microfacies of Sâ…¡+â…¢Reservoir are mainly underwater distributary channel endpiece, under water overbank sedimentary and distal bar, lithology are mainly siltstone and argillaceous siltstone, sandbody are clipped in the mudbank of interdistributary. In the case of monocline, because of lithology piching, Jiangqiao Area is the benefical target area of latent lithologic hydrocarbon reservoir.