Fine Description On Shabei Reservoir In Zhungaer Basin And Application Of Variogram

Considering the geological characteristics of fault complexity, sand’s multi-period stacking, quick variability of physical property between wells and strong heterogeneity of the Jurassic Xishanyao Formation in Shabei Reservoir, applying different exploration and development data, guided by the theory and technology of geostatistics, sedimentology, reservoir geology and reservoir description, study of sediment microfacies, physical properties, reservoir heterogeneity of the formation had been developed. Also,3D visualized geological model is set up. All these provided references for adjusting development in the oil-field. The main results of this dissertation are as follows:(1) The sand source for the Jurassic Xishanyao Formation in Shabei Reservoir is in North-East direction. Study area as a whole was near the source with shallow-water Deltas sedimentary environment, where developed four major sediment microfacies:underwater branch channel, mouth bar, sheet sand, and interdistributary bay. Delta front underwater branch channel is the main reservoir deposits, followed by mouth bar. They are the main oil-bearing sand bodies. We can found from the plane distribution of sand that underwater branch channel in the formation from layer 2-2 to layer 2-5 developed with large scale and contiguous stacking, belonging to the most developed time units.(2) The study area has the physical properties of medium porosity, low permeability, large variability, and strong heterogeneity. There is large difference for porosity and permeability between layers. Some mudstone interlayers are developed. The plane distribution of sand has a trend of thinning from the northeast to southwest.2-2 layer,2-3 layer, and 2-4 layer are formations with the most extensive distribution, strong continuity, and good property condition, and they are the main layers in Shabei reservoir. Heterogeneity within layers is strong.(3) According to the proposed classification criteria, the pore structure in the study area mainly belong to type II and type III. Clay minerals include illite, illite/montmorillonite and chlorite. The distribution of them has a close relationship with the burial depth, sedimentary facies, and fluid medium.(4) Comprehensive utilizing various types of data and statistical parameters, combined with reasonable stochastic simulation algorithms, geological structure model which reflects the geological structure is built with Petrel software; deterministic facies model and object-based stochastic facies model are set up; based on the facies model, petrophysical property model is also developed. For the facies model, stochastic model is closer to the actual channel distribution patterns than the deterministic model. They appear very close to the plane microfacies distribution and play mutual authentication.(5) Variogram plays a very important role in building 3D geological model. For providing the reliable sandbody input for object-based facies model, a new method is proposed to determine the sandbody geometry parameters with indicator variogram, and for the purpose of getting stable range for this method, range is got through reverse educing from the geometric offsets based indicator variogram model. In addition, using variogram star-shape map representing logging curve characteristics, microfacies are finely identified to meet the target of offering reasonable conditional data for object-based stochastic model.