Research on quantitative analysis method of shale oil reservoir sensitivity based on mineral analysis

Abstract

Mineral compositions of shale reservoirs are complex and highly influenced by external fluids. At present, there are limited studies on the effect of mineral expansion rate on external fluids, and there is a lack of systematic research on the sensitivity of shale reservoir porosity to external fluids. In this paper, firstly, X-Ray Diffractometer (XRD) experiments were carried out to study the mineral composition of shale reservoirs, revealing the mechanism of shale minerals interacting with acidic/alkaline fluids. Secondly, the sensitivity evaluation experiments of single mineral external fluid immersion were conducted on the main minerals in shale. Finally, a prediction method for the sensitivity of shale reservoir porosity to external fluids (acidic/alkaline fluids, oil slicks) was established. The results show that: (a) Volume expansion of quartz after 48 hours of immersion in alkaline fluids at pH=9 and pH=11 and the expansion rate is maximum at pH=9 i.e. 0.16. (b) Volume expansion of chlorite after 48 hours immersion in alkaline fluid and maximum expansion at pH=13 i.e. 0.55. (c) The improvement of total porosity of shale by acid solution is weak. (e) Alkaline solution has a weak damage to the total porosity of shale, and the degree of damage increases and then decreases with the increase of the strength of alkaline solution.