Abstract
This paper takes the ultra-low permeability sandstone reservoir of Jingbian oilfield in Ordos Basin as the research object, analyzes the petrological characteristics, diagenesis, physical characteristics and pore structure characteristics of the reservoir, and carries out reservoir sensitivity evaluation by using rock casting thin sections, X-ray diffraction, and sensitive flow experiments. The research results show that the ultra-low permeability Chang 6 sandstone reservoir has weak velocity sensitivity, medium-weak water sensitivity, weak salt sensitivity, weak alkali sensitivity and strong acid sensitivity; the damage mechanism of reservoir sensitivity mainly depends on the composition of clay minerals and pore structure after diagenesis. The clay mineral content from high to low is chlorite, illite, a small amount of illite / smectite layer, and kaolinite, of which the chlorite content is as high as 75 %; the reservoir has poor physical properties, the types of small hole-thin throat and small hole-fine throat. The reservoir is prone to blockage such as bridge plugging. Therefore, ultra-low permeability sandstone reservoirs are prone to different degrees of sensitivity. The reservoir characteristics are consistent with the reservoir sensitivity evaluation results.
Highlights
At present, the proportion of proven oil and gas reserves of low-permeability oil fields in my country is increasing year by year, and has great development potential [1-2]
Due to the high content of clay minerals in ultra-low permeability sandstone reservoirs, the reservoir space is mostly composed of micropores and fine throats, with poor seepage capability, which leads to more complex reservoir sensitivity [1-2]
Taking Chang 6 reservoir of Jingbian oilfield in Ordos Basin as the research object, this paper evaluates its sensitivity characteristics and analyzes the basic characteristics of reservoirs comprehensively to study the mechanism of reservoir sensitivity damage by the laboratory experiments, which provides a certain reference for similar reservoirs
Summary
The proportion of proven oil and gas reserves of low-permeability oil fields in my country is increasing year by year, and has great development potential [1-2]. The Jingbian oilfield in the Ordos Basin is a typical lowpermeability oilfield This type of oilfield has the characteristics of "low permeability, low production, and low pressure". It is necessary to conduct research on reservoir protection and formation damage evaluation, analyze the interaction mechanism of reservoir-sensitive minerals and external working fluids, reservoir seepage capacity, and evaluate reservoir sensitivity [3-5] to achieve the purpose of efficiently developing ultra-low permeability sandstone oil fields. Taking Chang 6 reservoir of Jingbian oilfield in Ordos Basin as the research object, this paper evaluates its sensitivity characteristics and analyzes the basic characteristics of reservoirs comprehensively to study the mechanism of reservoir sensitivity damage by the laboratory experiments, which provides a certain reference for similar reservoirs
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