Geology Characteristics Research Of Mabei Block In Santanghu Oilfield

With the area of 2.3×104km2, Santanghu basin is a overlapped and reformed intermountain basin located between Altai mountain system and Tiansha mountain system. According to charateristics of tectonic and sedimentary combination, the basin can be departed into thrust-uplift belt in northeast, central sag and thrust-nappe belt in southwest, totally three 1st level structural units. Mabei block is located to the east of Niujuanhu block in Santanhu oilfield and to the west of Niudong oilfield. Its structural location is in Niujuanhu-Niudong structural belt in the front of Tiaoshan uplift beltMabei block, with the area of 12.85km2 and proved reserves of 1230×104t, is constucted by Hu219 block and Ma46 block. Its target formation is Xishanyao formation of middle Jurassic system. Oil layers’ vertical depth in Hu219 block and Ma46 block are separately 1200~1800m and 769~1172m. The reservoir is front braided river delta underwater distributary channel sedimentary with poor physical property, average porosity of 15.5%, average permeability of 9.45×10-3μm2 and strong heterogeneity, the lithology of it is mainly feldspar lithic sandstone. Single oil layers’ thickness interval is 2~12m, the thickest layer is 17.6m. The reservoir is layered structure lithology reservoir with low temperature and pressure, and its temperature gradient is 2.3℃/100 m, pressure coefficient is 0.71~0.83. The oil in Hu219 and Ma46 block is heavy oil with viscosity of 67~2443mPa·s. Seismic inerpretation and inversion are done during the research to renew the undertanding of structure, the target formation’s sub-layer division and four properties’ relationship are also done. Then the reserves is recaculated. According to preliminary understanding of reservoir characteristics, horizontal well pilot experimentation is done. The target formation’s important data is aquired by horizontal well geosteering and core aquisition, finally renewed the undertanding of geology characteristics and reserves.Maping23-35 and Mashi5 well conducted steam stimulation test, concluded Ma46 well area low permeability reservoir, absorb steam ability poor, low 0il saturation, be a limited number of mobile oil.