Study on Meso-Structures and Flow Characteristics of Oil Sands in Qigu Formation of Fengcheng Oilfield

doi:10.7657/XJPG20210414

Abstract

Abstract:

In order to clarify the meso-structures and flow characteristics of oil sands in the Jurassic Qigu formation in Fengcheng oilfield, a three-medium image segmenting method suitable for oil sands was proposed by using micron CT grayscale images and conventional image segmenting method. Using the new method, digital oil sand cores were obtained from physical experiments, and finally a pore network model was built. The research shows that when constructing digital oil sand cores, it is necessary to propose a three-medium image segmenting method suitable for oil sands on the basis of the binary image segmenting method for porous media, to distinguish the particles, asphaltenes and pores in oil sands. Only when the side length of the representative volume unit of a digital core is greater than 3.0 mm, it can truly reflect the meso-structures of oil sands. The contact between particle and asphaltene in the oil sands of the Jurassic Qigu formation in Fengcheng oilfield are divided into three types: particle contact, cementing contact and suspending contact. Furthermore, the oil sands are strongly heterogenous and anisotropic, and asphaltene as a part of framework or as pore fluid, its absolute permeability is about 2 orders of magnitude higher than the effective permeability. As a result, the phase state of the asphaltene significantly affects the meso-structures of the oil sands.

Key words: Fengcheng oilfield, Qigu formation, oil sand, porous medium, micron CT, image segmentation, digital core, meso-structure, flow characteristic

CLC Number:

TE112.3

PANG Huiwen, JIN Yan, GAO Yanfang, WANG Qiqi. Study on Meso-Structures and Flow Characteristics of Oil Sands in Qigu Formation of Fengcheng Oilfield[J]. Xinjiang Petroleum Geology, 2021, 42(4): 487-494.

Figures/Tables 10

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