Injection Mechanism And Application, Of The High Moisture Content Of Sandstone Oil Field Cycle

This chapter set forth in detail that capillary force and elastic force improve macroscopic and microscopic action mechanisms of heterogeneous sandstone field development effectiveness by a lot of aspect such as laboratory core oil displacement experiment, theory analysis and lease information interpretation etc in the course of cyclic water injection, consider overall capillary force, elastic force and gravity's influences, establishes cyclic water injection mathematical model in heterogeneous sandstone reservoirs, the model considers flow items caused respectively by displacement pressure, capillary force and gravity. According to flow character of each flow item in the course of cyclic water injection, then it sets forth a new method to obtain flow coefficient which overcomes the default of generously used "upstream"weight coefficient method , based on which it derives numerical solution of theoretical model and carries out stability analysis .The model can describe accurately absorptive percolation phenomena caused by capillary force and additional channeling flow phenomena caused by elastic force and work out cyclic water injection numerical simulation software correspondingly。In the course of working out software, aiming at the defects which exists in common numerical simulation software, this chapter considers sufficiently underground liquids'seepage flow characters in different cyclic water injection period, improves treatment methods of relative permeability curves and capillary force curves, increases calculation precision of cyclic water injection dynamic indexes, the magnitude that recovery efficiency increases accords in more highly degree with lease actual values.。It applies the simulation software to analyze quantitatively how objective factors such as capillary force,elastic force,gravity,oil viscosity,oil reservoir rhythmic nature,oil reservoir longitudinal heterogeneity,vertical permeability etc and subjective factors such as cyclic water injection manners,oil well and water well work system,cyclic water injection starting time etc influence cyclic water injection effectiveness, to confirm reservoir types and reasonable water injection manners that are suitable to cyclic water injection。The conclusion is: capillary force is in first ,elastic force is in second , water-wet oil reservoir is more suitable to cyclic water injection。In order to verify calculation results in theory ,it carries out shop experiment and on-site actual cyclic water injection effectiveness evaluation calculation。In terms of geologic characters in heterogeneous sandstone reservoirs, it designs plane heterogeneous and vertical heterogeneous core experiment physical model, carries out cyclic water injection and conventional water injection experiments, results show that the magnitude recovery efficiency increases is 1.5%-2.5% to water-wet core , to oil-wet core the value is about 1.0%, and verify capillary force is one of main influential factors in cyclic water injection.。At last, combining production practices in three cyclic water injection experiment areas in DAQING Oil Field, the chapter carries out cyclic water injection development effectiveness evaluation, practices shows that in water-wet oil reservoirs cyclic water injection's effect is better than in oil-wet oil reservoir, the former may increase recovery efficiency about 1.5%, while the latter may increase recovery efficiency less than 1.5%。At the same time, it analyzes and contrasts different cyclic water injection manners'shortcomings and advantages, gives reasonable interval water injection cycle and water injection amplitude of fluctuation and provides foundation and reference in theory for setting down cyclic water injection projects in heterogeneous sandstone fields。...