Two-dimensional NMR fluid interpretation theoretical map partitioning of continental shale oil: a case study of continental shale in Qingshankou Formation, Songliao Basin

Abstract

The continental shale oil reservoirs in the study area not only have high clay content and complex pore structure, but also have developed laminaceous foliation and strong anisotropy. Laboratory core analysis is an important means to study the rock and fluid properties of shale oil and gas reservoirs. Because shale cores swell with water and are fragile, conventional experimental methods for sandstone are no longer suitable for shale core analysis, so laboratory petrophysical analysis methods for shale oil reservoirs need to be developed. At present, the two-dimensional NMR spectrum fluid identification plate under shale oil laboratory conditions is controversial at home and abroad, so the research work of establishing two-dimensional NMR spectrum fluid identification plate is carried out for continental shale in the study area. In this paper, from the rock physical property analysis of shale reservoirs, combined with the feature of Qingshankou Formation continental shale reservoir in the study area, to carry out high temperature carbonization saturated water and saturated oil, dry samples, analysis of shale nuclear magnetic response characteristics of different pore space fluid, establish suitable for the study area of continental shale two-dimensional nuclear magnetic resonance (NMR) spectra fluid identification chart. The conclusion of this paper is that with the increase of temperature, the signals of clay interlayer, pore and macropore gradually decrease, until the carbonization temperature reaches 704℃, the nuclear magnetic signal can't be measured; The nuclear magnetic spectrum of saturated fluid in the dry distillation core shows that kerogen and hydroxyl signals disappear completely, and a large amount of self-absorbed saturated water enters clay layers, while the nuclear magnetic signals in clay layers, small holes and large holes of saturated oil cores increase obviously. The nuclear magnetic spectrum of saturated fluid after dry distillation shows that clay interlayer can be used as the storage space of crude oil, and the nuclear magnetic signals of oil and water in clay interlayer are obviously different.