Oil Control Factors Research Of Chang 9 Reservoir In Hujianshan Area

Hujianshan area is at in the Shanbei Slope locating at the middle-west part of the Ordos Basin, which is the most important oil-gas producing area in this basin. Oil-bearing series of the study area are Chang 8, Chang7, Chang6, Chang 3 and Jurassic, the production scale are gradually expanding and shows good development prospects of Hujianshan area. In recent years, Chang 9 reservoir of Hujianshan area is the new exploration formation, in-depth study of the oil control factors of Chang 9, to form the regular understanding, and guide significance for the Chang 9 formation of the next exploration and development, and provide strong geological evidence for Hujianshan area to increase reserves and production.Based on previously study achievements, coring data, logging data, test analysis and oil testing, and under the teaching of theories in some relevanting things, such as geo-sequence stratigraphics, geo-sedimentology, well-logging and geology of petroleum, this geology study is focusing the important sedimentary facies, reservoir characteristics and oil-controling factors of Chang 9 formation based on the geologic settings and finally point out the promising zones.The paper shows that Hujianshan Chang 9 area which has a low structure is as some nose-shaped uplifts on west dip monocline. The sedimentary systems of Chang 9 of Hujianshan area is delta deposition, the northern part of study area develops delta plain facies and the south of study area develops delta front facies, specifically divided into distributary channel, subaqueous river-distribution channel, natural blocking barriers, subaqueous natural blocking barriers, interdistributary embayment and swamp microfacies. The sandstones are mainly middle-fine grained feldspathic sandstone with grayish-white and grayish-green, and the main cementing minerals are as follows, for example, illite, silicious and ferritin calcite, the main pore-typing system are inter-granular pore and feldspar dissolution pore. The diagenetic effections of the researching area including compacting effection, pressure-soluting effection, cementating effection, dissoluting effection and metasomating effection, are reached mid A diagenetic stage; The pore average value is 9.87% and the average of permeability is 0.847×10-3μm2, Generally speaking, Hujianshan Chang 9 reserving system is part of low-extralow porosity and extralow permeability reserving system.Above those researching achievements, a systematic study has also been done to the enrichment factors and distributions of oil-gas in Hujianshan area. Analysis shows hydrocarbon source rocks of Chang 7 provides organic carbon for Chang 9 reservoir; Sand bodies in distributary channel is important reservoirs; Lenticular sandbody and mud sediment in up-dip is the guarantee of oil and gas accumulation; Superimposed distributed channel sandstone and the microcrack system are the dominant migration pathway. Combing with the above research, Chang 9 oil-bearing reservoir controlling factors of Hujianshan area are finally summarized.