Progress and prospect of experimental technologies for continental shale oil development

Abstract

As shale oil exploration and development intensifies， the experimental technologies for shale oil development have been continuously improved while inheriting the experimental technologies and methods of conventional reservoirs and shale gas reservoirs， and a set of experimental technology systems of reservoir physics and flow mechanisms has been initially formed， which provides strong technical support for geological evaluation of shale reservoirs， reservoir engineering optimization design， and enhanced oil recovery. The development status of six experimental technologies in China and abroad， including porosity， permeability， oil-water saturation， wettability， relative permeability， and imbibition， was systematically summarized. In view of the characteristics of continental shale oil， such as low maturity， strong heterogeneity， and well-developed lamina and micro-fractures， the measurement methods and principles， key influencing factors， control conditions of experiments， advantages and disadvantages and technical applicability of experiment methods were analyzed. The main problems， development trends， and research direction of these experimental technologies were put forward. The results show that ① unifying the cleaning agent and cleaning time of rock samples is the key to improving the comparability of different measurement methods of porosity， and nuclear magnetic resonance measurement of porosity is the technological development direction to meet the needs of rapid analysis in mining fields； ② the irregular and multi-directional permeability measurement technology capable of simulating formation pressure changes is the future technological development direction； ③ the alcohol soaking method and two-dimensional nuclear magnetic resonance （T1-T2） method are the technological development direction of the determination of shale oil-water saturation， but they still face the problem of the influence of clay bound water and adsorbed oil on the determination accuracy； ④ the droplet morphology method is one of the future development directions of measurement technology of shale reservoir wettability， which requires further research and unified standards in experimental methods and comprehensive evaluation methods for surface wetting and spontaneous imbibition processes； ⑤ the combination of experimental measurement and numerical method is an effective way to obtain the relative permeability of shale reservoirs， and the micro-oil and water metering， end-effect correction， as well as technologies and methods considering the time-varying pressure are the key directions； ⑥ pressure imbibition measurement method should be used to evaluate imbibition effect and optimize well kill time in elastic development after fracturing. Pressure imbibition measurement methods based on nuclear magnetic resonance T2 spectrum， stratification T2 spectrum， and T1-T2 spectrum will be one of the essential technological development directions.

Keywords

• continental facies
• shale oil
• experimental development technologies
• porosity
• permeability
• oil-water saturation
• wettability
• relative permeability
• imbibition