Study On Micro Pore-throat Structure Of Tight Oil Reservior And Its Evaluation Method

Tight oil reservoir has got lots of attention as the development of Unconventional oil and gas.China have made breakthrough in Exploration work and geological research.Tight oil development has been launched in some oil fields.It is very important to further study the micro pore and throat Structure for the target of improve the tight oil recovery efficiency.On the other hand,oil field is badly in need of an appropriate Evaluation method to guide development.In this paper,the author chose the tight sandstone and tight limestone as research subjects.Many laboratory experimentations were used among this problem,such as constant rate mercury injection,nuclear magnetic resonance combined with centrifuge experiment,nonlinear seepage experiment and so on.Based on those experiment data,author analyzes the he micro pore and throat Structure characteristics,the non-linear seepage characteristics,and micro occurrence regularity of tight oil reservoir.A point of view that the average throat radius the start up pressure gradient and the rate of movable fluid can be used to describe the flow process in tight reservoir.Considering the very low production of tight oil well and the indispensable stimulation treatment,this paper study the relationship among the rock brittleness,the formation pressure and production.A fact is deemed that the difference between and Saturation pressure,brittleness index,viscosity and clay content are related to the development potential of tight oil reservoir.Those above 7 parameters are proposed to evaluate tight oil reservoirs.Then a comprehensive classification method is proposed,which divide tight oil reservoirs into 4 levels according to comprehensive classification parameters.this method is used in typical tight oil reservoirs,and can give advices for reservoirs evaluation.This research shows that the average throat radius,the start up pressure gradient,the rate of movable fluid,the difference between and Saturation pressure,brittleness index,viscosity and clay content are appropriate parameters to evaluate tight oil reservoirs.The comprehensive classification index(CCI)can quantitatively and synthetically considers all factors of tight oil reservoirs.