A New Type of High Temperature Clean Fracturing Fluid to Enhance Oil Recovery on Bohai Bay, China

This paper introduces a new type of high temperature clean fracturing fluid to enhance oil recovery on Bohai Bay of China. Compared with conventional polymer fracturing fluid, clean fracturing fluid has many advantages, such as few components, easy preparation, good prop-carrying capacity, low treatment friction, no residue, low damage to formation, and automatic gel-breaking. But because its high temperature performance is poor, it limits its application in high temperature reservoir. The current clean fracturing fluid system is only applicable to the reservoir which temperature is below 120° C while high reservoir temperature above 140° C is still one difficult technical problem for fracture engineers. Clean fracturing fluid system VES-140 which could be used in high temperature reservoir has been made through various experiments such as synthesis of main agent VES-140° and optimization of the activator and counter ion. It is indicated by the results of fracturing fluid rheology test that at 140° C, after shear of 2 hours at 170s⁻¹, viscosity of the fracturing fluid is more than 50mPa.s. Storage modulus of the fracturing fluid is 3.5Pa, while loss modulus is 1.5Pa. According to the experiment results it has excellent viscoelasticity and good prop-carrying capacity. This fracturing fluid system has no residue therefore it has no solid-phase damage to reservoir. The fluid damage to formation is around 14.67% far less than conventional fracturing fluid.