Study On The Characteristics Of The Shahejie Formation In Tongkou District Of North-central Lixian Slope

Tongkou area is located in north-central part of the Lixian Slope. With the breakthrough ofexploration and accumulation of scroll building knowledge and information, the change ofshahejie formation in the study area is large, and the oil-water relationship is complicated. Theproblems of petroleum geological understanding and development are increasingly prominent,and they always trouble the oilfield construction and the whole development effect. Therefore,we need study the fine geological characteristics and reservoir classification evaluation deeply,and make clear the exploration potential of the area, which has very important practicalsignificance to the sustainable development of Huabei oilfield.In this paper, the Shahejie formation is the research object. Based on well core, logging andtesting data, with petroleum geology, sedimentology and reservoir geology theory as theguidance, combining with thin section analysis, X-ray diffraction, scanning electron microscope,mercury injection and other analysis methods, the sedimentary facies, reservoir characteristics ofshahejie formation in this area is in-depth systematic studied, and on this basis, combining withthe oil enrichment regularity, the favorable exploration area is forecasted.The research shows that the Shahejie formation can be divided into the upper and lower ofEs1, the upper and lower of Es2, the upper,mid and lower of Es3. The study area is in the nasalstructure belt, and greatly influenced by fault. The main sedimentary facies of the study area arebraided river delta sedimentary and shore shallow lake sedimentary, and the main sedimentarymiro-facies are subaqueous distributary channel,underwater distributary channel, and the mouthbar. The river was from northwest to southeast, and the provenance mainly comes from thenorthwest. Its mian diagenesis includes compaction, cementation, metasomatism and dissolution.Among them, compaction and cementation damages the reservoir intensively. The main rocktypes of the reservoir are feldspar sandstone and feldspathic lithic sandstone, various pore types,a poor reservoir property, and it is mid-low porosity, low-ultra low permeability reservoir. Theinlayer, interlayer and horizontal heterogeneity of the study area are relatively strong. Reservoirdamage is interiorly evaluated, and it mainly shows no medium~weak velocity sensitivevelocity sensitive, no water sensitivity~weak water sensitivity, medium weak~extremelystrong acid sensitive or no acid sensitivity and non-alkali~medium to weak alkali. The oil andgas accumulation of Shahejie formation in this area is mainly controlled by hydrocarbon sourcerock distribution, tectonic fracture activity, reservoir physical property and sedimentary facies.Various reservoirs mainly distributes in main channel with large thickness sandstone and goodreservoir property.