Interpretations of Stratigraphic Inclines and Fractures of the Low Hill Carbonate Reservoirs, Liaohe Depression, Northeast China

Guohui Li¹, Susan M. Schrader², Robert S. Balch², and Roger Ruan^2
1 Institute of Energy Science of China University of Geosciences, Beijing, China
² New Mexico Tech Petroleum Recovery Research Center, Socorro, NM

Low hill carbonate reservoirs play an important role in the hydrocarbon accumulations in some depressions in East China. Field studies during exploration and development have revealed that the interior features of low hill reservoirs vary greatly and are often too complicated to be interpreted by the seismic data due to their small sizes. Often when a low hill is structurally identified, further techniques should be applied to determine the stratigraphic inclines, status of fractures, porosity and permeability, and the spatial heterogeneity of the interior parts of the low hill.

The petrologic types and the spatial assemblies of the low hill reservoirs influence the reservoir heterogeneity and hydrocarbon occurrence. Thus, this work utilizes petrological and stratigraphic methods to integrate the interior structures by using the cores and well logging data correlation, especially the dip loggings. The direct observations of cores, conventional well logging data, and the CBIL, FIT and DCA techniques have been used to identify the existence of fractures and to assess the fracture density, length, width, orientation, and networks quantitatively. Also, three dynastic discriminant functions, degree of the bore-hole ellipsoid, deep-shallow resistance rate, and uranium abnormity have been set up to distinguish fractures.

Dual system models of the fracture reservoirs have been proposed to calculate parameters such as porosity, permeability and water saturation. This detailed characterization of the low hill carbonate reservoir is integrated with the combination of macro and micro properties of the hill, which aids in understanding the nature of hydrocarbon accumulations.