Study on Reservoir Physical Properties of Oil Shale During Heating in Minhe Basin

doi:10.7657/XJPG20200204

Abstract

Abstract:

In order to study the influences of heated hydrocarbon expulsion process on reservoir physical properties of oil shale, selecting the immature oil shale in Minhe basin as the research object, reservoir physical properties of the oil shale samples in different heating stages are analyzed by means of 3D scanning observation of cracks, high-pressure mercury intrusion experiment, low temperature nitrogen adsorption and X-ray diffraction analysis after low temperature carbonization, and the evolution of oil shale reservoir physical properties during heating are further revealed. The results show that in the stage of low temperature heating (185-350 ℃), small amount of hydrocarbon is expulsed from the oil shale and the production rates of oil-water and semicoke change a little; in the stage of medium temperature heating (350-475 ℃), large amount of hydrocarbon is expulsed from the oil shale, the production rates of oil-water and semicoke significantly rise; in the stage of high temperature heating (475-520 ℃), residual hydrocarbon is expulsed and the production rates of oil-water and semicoke remain the same. During the heating process of the oil shale, as the temperature rises, the amount of cracks increases, micro-cracks widen and extend and then large fractures are formed. The fractures are mainly developed at the bedding surface and there are no obvious fractures on vertical bedding surface. The specific surface area of the oil shale gradually increases, micro pores become large pores. With the expulsion of hydrocarbon, partial large pores connect with each other and micro fractures are formed. The adsorption of the semicoke in the oil shale increases with the rise of relative pressure and temperature and the clay content decreases. The smectite in the illite/smectite formation gradually transforms into illite, the grain sizes of minerals desease, leading to the forming of micro fractures in mudstone and finally the porosity and permeability of mudstone increase.

Key words: oil shale, staged heating, reservoir physical property, hydrocarbon generation, low temperature carbonization, low temperature nitrogen adsorption, high-pressure mercury intrusion experiment, pore evolution

CLC Number:

TE112.23

ZHAO Kang’an, SUN Pingchang, YU Fengning, LIU Rong, ZHANG Daoyong. Study on Reservoir Physical Properties of Oil Shale During Heating in Minhe Basin[J]. Xinjiang Petroleum Geology, 2020, 41(2): 158-163.

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