| Popis: |
To improve water injection efficiency in buried hill reservoir, taking B fault block of Chad as an example, the reasonable water injection pressure under different nature fracture parameters and operation strategies is summarized. Stress sensitivity is studied by physical simulation, and the impact of injection pressure under different factors on production is analyzed via numerical simulation considering fluid-solid coupling, additionally using Response Surface Design optimizing injection pressure. Results show: Stress sensitivity is induced by fracture closure and plastic deformation of rock, and permeability irreversible damage is obvious on the condition of fracture dip angle less than 30°, meaning strong sensitivity. Considering fracture dynamic change under depletion and waterflooding, there is a reasonable range for injection pressure, leading to optimal production state, also when replenishing reservoir pressure and displacing velocity achieve a reasonable matching relation. The main control factors on reasonable injection pressure include fracture density, injection timing and fracture strike. Finally, prediction model of reasonable injection pressure is built by Response Surface Design. This study makes the impact of injection pressure on production in buried hill reservoir explicit, and provides a useful guide for strategies of replenishing energy by waterflooding after depletion. |
