Study on Granite Buried Hill Reservoir Characterization and Modeling of Offshore S Oilfield in Bohai Bay

Abstract

Granite buried hill reservoir is rare in the world. Current research on it is still at a relatively low level. No systematic research thinking and methods on Granite buried hill reservoir has been formed so far. Meanwhile, as the reservoir was multiply reconstructed by tectonic, weathering and erosion processes, pores, fractures and caves developed inside together. So it's difficult to characterize the reservoir as it represents dual porosity property and fractures developed with strong heterogeneity. For this reason, the article proposed a set of methods for granite buried hill reservoir characterization and modeling, taking offshore s oilfield in Bohai Bay as an example. Due to the particularity of the reservoir, not only matrix but also fracture of the reservoir has to be characterized and modeled. So conventional modeling technique is used for matrix. But for fractures, a new method has been proposed in the article. Firstly starting from fracture genetic analysis, geomorphologic analytic method is innovatively introduced to determine main controlling factors of fracture distribution. Through evolutionary characteristic analysis for grooves and ridges geomorphology, two types of fractures that developed in the study area are ensured, including local structural fractures which came from fault system as well as regional structural fractures controlled by grooves and ridges geomorphology feature. So on the basis above, fracture development zone trend models for two fracture types are established. Secondly with advanced DFN method, the DFN model is built with statistical fracture parameters (length, aperture, density etc.) of well point as prior information and fracture trend models as constraint condition and then fracture attribute (porosity and permeability) models have been built with upscaling method. Finally fracture attribute models are verified and optimized with static and dynamic data. With two methods of verification and trend restraints for quality control of fracture model, the ultimate fracture model is accordant with the geological understanding. Through building dual models for both matrix and fracture, accurate characterization for granite buried hill reservoir is achieved which provide credible geological foundation for oilfield development plan and precious technical reference for similar reservoir characterization and modeling research.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015