超零界二氧化碳无水压裂增稠剂实验研究

二氧化碳在温度高于临界温度Tc=31.26℃,压力高于临界压力Pc=7.4 MPa的状态下,性质会发生变化,变化为一种介于气体与液体之间的流体,其密度近于液体,粘度近于气体,扩散系数为液体的100倍,因而具有惊人的溶解与渗透能力。将其与增稠剂混合,使其在高温高压下仍能保持高黏度,耐剪切性、流变性、悬砂性等性能良好的压裂体系,渗透至岩石天然裂缝中,利于复杂网格裂缝的形成,并且由于其超低的界面张力可以做到无残渣易反排,降低对储层的伤害。

Experimental Study on Supercritical Carbon Dioxide Anhydrous Fracturing Thickener

When the temperature is above the critical temperature Tc=31.26 ℃ and the pressure is above the critical pressure Pc=7.4 MPa, properties of carbon dioxide will vary, it will be a fluid between the gas and the liquid, its density is near to that of the liquid, its viscosity is near to that of the gas, its diffusion coefficient is 100 times as high as the liquid's diffusion coefficient, so it has amazing dissolution and penetration ability. After the supercritical carbon dioxide is mixed with thickeners, the mixture can keep high viscosity at high temperature under high pressure, and can be used as the fracturing system with good shear resistance, good rheological characteristic, high suspending sand performance; it can penetrate to the natural fractures in the rock, which is beneficial to the formation of complex grid cracks; and due to its ultra-low interfacial tension, fracturing fluid flowback is easy, which can reduce the damage to the reservoir.