APPLICATION OF R/S ANALYSIS IN FRACTURE CHARACTERIZATION AND PREDICTION OF ULTRA-LOWPERMEABILITY SANDSTONE RESERVOIRS IN ZHENBEI OILFIELD. ORDOS BASIN

摘要

Fracture characterization and prediction has al- ways been a difficult research topic in ultra-low per- meability sandstone reservoirs. Taking Triassic Chang 81 reservoir of Zhenbei Oilfield in Ordos Ba- sin as an example, based on the origin and type of reservoir fracture, the fracture parameters in Zhenbei area are characterized qualitatively and quantita- tively by combining field outcrop, core analysis and imaging logging data. Using variable scale fractal technology in fractal geometry, the acoustic interval transit time and conventional natural gamma logging data are processed non-linearly, thus a new R/S anal- ysis curve is constructed, combined with imaging logging data, to identify and predict the favorable ar- eas for the development of structural fractures. Theresults show that the R/S analysis curve has obvious linear characteristics and its fractal dimension shows positive anomaly in the fracture development section. Compared with the imaging logging and the initial productivity of the well, the method has high detec- tion accuracy and universal applicability. The pre- dicted fracture development favorable zones in Z area are strip-like distribution, mainly in NE-SW di- rections, which provides a basis for the formulation of later development policies in this area, and has reference value for the prediction of inter-well frac- tures in other ultra-low permeability sandstone res- ervoirs.