Nitrogen And Water Flow Experiments In Microtubules And Low-Permeability/tight Cores

For the abnormal flow of gas and liquid in low permeability/tight reservoirs,nitrogen with high pressure and water flow experiments in microtubules and low permeability/tight cores were conducted to investigate the flow characteristics in micro pore throat.Using the novel High Pressure Dynamic Micro Differential Pressure Gauge,Nitrogen with high pressure and low velocity flow experiments were conducted in 2?m?5?m?25?m?33?m?45?m microtubules.According to the results,velocity with not varies with gas pseudo pressure gradient as predict by slip theory.In the low velocity area,the velocity measured is higher than the velocity first order slip rules,and the dimensionless drag coefficient measured is lower than it is calculated by first order slip rules.The decrease of gas flow velocity varies inversely with the difference between velocity measured and it calculated.With the increase of pressure,this difference decreases and disappears at high pressure.How nitrogen flows in 0.01mD~2500mD cores is similar with how nitrogen flows in microtubules.The novel device is design to measure the threshold pressure gradient in low permeability/tight core,and it aims at using the compressibility of gas to control the inject speed of fluid,which makes the threshold pressure be measured.With the assist of the novel devices,the start pressure dynamics was investigated in 0.7?m?1?m?2?m?5?m microtubules.The results show that there is a pressure drop on the pressure differential dynamic curve and this pressure drop not varies with the inject speed of pump.The pressure drop is also apparent on the pressure differential dynamic curve of core experiment.How the pressure differential dynamic curve varies in the core is similar with it in the microtubules means that this pressure may exists relationship with the threshold pressure.The non-Darcy flow in low permeability/tight cores was conducted and the results combined with the achievements of predecessors delineate how the non-Darcy flow characteristics varies with flow velocity.Based on the non-Darcy flow results,this study also focus on the sweep efficiency of water-flooding in low permeability/tight reservoirs,and use the mobility to describe heterogeneity of fluid and petro-physics distribution.The calculation shows that with the increase of coefficient of mobility variation,the vary of sweep efficiency is from flat to rapid decline and become slow in the high coefficient of mobility variation range;besides,the sweep efficiency varies directly with the average mobility of reservoirs,and water channeling becomes much more serious.